AP Cybersecurity · ⁨AP ความปลอดภัยทางไซเบอร์⁩

Learning Objective 1.1.A: Identify common indicators of social engineering tactics.

• 1.1.A.1 Social engineering attacks employ psychological tactics to manipulate users into revealing sensitive information (elicitation), downloading a malicious file, or clicking on a malicious link. Social engineering can be performed in person but is often done by email, by text message, or through social media messages.
• 1.1.A.2 Adversaries often use psychological tactics like intimidation and urgency to achieve their goals. Intimidation is when an adversary threatens a target with negative consequences if they don’t comply. Urgency is when an adversary creates reasons why a target should act quickly.

Learning Objective 1.1.B: Explain how social engineering tactics influence victims to perform a desired action.

• 1.1.B.1 Social engineering tactics rely on common psychological principles that influence human behavior.
• 1.1.B.2 Intimidation leverages a natural human aversion to negative consequences. By drawing attention to possible negative consequences, adversaries use fear to incite targets to act.
• 1.1.B.3 Urgency leverages a natural human response to react quickly to time-sensitive needs. When targets detect a sense of urgency in a message, they feel pressured to respond or act quickly, which can prevent them from taking the time to consider whether an action is reasonable or safe.

Learning Objective 1.1.C: Describe possible impacts for victims of social engineering attacks.

• 1.1.C.1 Victims may give an adversary personal information that could lead to impersonation, such as name, phone number, address, workplace, pets’ names, or birthdate. These types of information, and information like them, are often used on websites as challenge questions to verify a user’s identity.
• 1.1.C.2 Victims may give an adversary secure information like a one-time password (OTP) or authentication login code, which could allow an adversary to log in to a service as the victim.
• 1.1.C.3 Victims may download malware or click a link that installs malware on their device, steals information from their web browser, or directs them to a website where their login credentials can be captured by an adversary.

Learning Objective 1.2.A: Identify common signs of a password attack.

• 1.2.A.1 In an online password attack, adversaries try logging in to a device or service using common passwords, common password patterns, or stolen passwords.
• 1.2.A.2 Signs of an online password attack include:
  • Many failed attempts to log in over a short duration
  • Login attempts at unusual times
  • Login attempts from unknown devices

Learning Objective 1.2.B: Explain how adversaries take advantage of weak authentication.

• 1.2.B.1 Many people use common patterns when creating passwords, such as:
  • Starting a password with one or two words, adding a two-digit number (often signifying a year), and putting a special character at the end
  • Including the names of family or pets in their passwords
  • Including personally significant dates in their passwords
• 1.2.B.2 Adversaries often construct a dictionary of possible passwords based on personal information gathered about a target (e.g., birthday, anniversary, names of pets and family) and use an automated tool to submit potential passwords.

Learning Objective 1.2.C: Explain how to make authentication stronger.

• 1.2.C.1 Users should create passwords that are long, random, and unique. A password manager can be used to generate and store strong passwords, or a user may create long, unique passphrases for their accounts.
• 1.2.C.2 When creating passwords, users should avoid names, dates, or other personally meaningful words or numbers.
• 1.2.C.3 When available, users should enable multifactor authentication (MFA), which will require the user to provide extra proof of identity—such as a one-time code—in addition to the password as an extra layer of security.

Learning Objective 1.3.A: Identify the type of adversary conducting a cyberattack.

• 1.3.A.1 Adversaries can be classified by their skill levels.
  • Low-skilled adversaries rely on malicious cyber tools created by others that can be purchased online. The tools they use exploit known vulnerabilities.
  • High-skilled adversaries have the capacity to create new malicious cyber tools or modify existing ones to adapt to new defensive techniques and tools. They also have the capacity to discover undocumented vulnerabilities, known as zero days.
• 1.3.A.2 Adversaries have a variety of motivations, including greed, desire for recognition, dedication to a cause, revenge, politics, or beliefs.

Learning Objective 1.3.B: Identify types of wireless cyberattacks.

• 1.3.B.1 In an evil twin attack, an adversary sets up their own wireless access point (WAP) with a service set identifier (SSID) similar or identical to a target network; the adversary’s network is called the evil twin. Victims of this attack could select to unknowingly connect to the evil twin, allowing the adversary to capture their network traffic. The adversary cannot read traffic that uses an encrypted protocol like HTTPS.
• 1.3.B.2 In a jamming attack, an adversary floods an area with a strong electromagnetic (EM) signal in the same frequency range as the wireless network, which prevents legitimate traffic between the access point (AP) and users. This type of attack that prevents users from accessing resources is called a denial of service (DoS) attack.
• 1.3.B.3 In a war driving attack, adversaries try to detect wireless network beacons while driving or walking around a target. If a wireless signal is detected, the adversary can gather information about the type of wireless network used and find areas where the wireless signal extends outside the physical building.

Learning Objective 1.3.C: Describe actions individuals can take to increase protection of sensitive data when using the internet and Wi-Fi.

• 1.3.C.1 Individuals should verify that the name of any wireless network they join exactly matches the name of the network they intend to join.
• 1.3.C.2 Most internet protocols are encrypted to protect network traffic. However, individuals may consider the sensitivity of their data in choosing whether to join unencrypted Wi-Fi networks to protect vulnerable data such as DNS queries.
• 1.3.C.3 Individuals may consider using a virtual private network (VPN), which encrypts all their traffic to the VPN operator’s system. Although this action prevents a service provider from viewing traffic, the VPN provider can view the traffic.

Learning Objective 1.4.A: Explain how adversaries use AI-powered tools to augment cyberattacks.

• 1.4.A.1 Adversaries can use AI-powered tools that leverage existing voice and image samples of a person to create a digital avatar of that person. The use of these technologies enables adversaries to impersonate someone over the phone or even on a video call, which can lead to financial loss or the sharing of sensitive or private information. As more organizations adopt voice-based authentication, the impact of voice-impersonation has a larger potential impact.
• 1.4.A.2 Adversaries can use generative AI tools, like large language models (LLMs), to create convincing phishing messages in any target language. Because traditional phishing messages are sometimes written by non-native speakers of the target’s language, unnatural language is a feature that has been used to distinguish phishing messages from legitimate messages. However, with AI tools, adversaries can now craft phishing messages in any language that read as though they were written by a native speaker.
• 1.4.A.3 Adversaries can craft prompts that extract secure or sensitive information from LLMs. Secure or sensitive information in LLMs can come from user input and the large data sets used to train LLMs.
• 1.4.A.4 Adversaries can publish websites or modify existing websites to contain false information so that the false information will be included in the training sets for LLMs, causing the LLMs to repeat the false information.
• 1.4.A.5 Adversaries can perform reconnaissance on a target using AI-powered tools that scan the internet to gather information posted on social media and public websites.
• 1.4.A.6 Adversaries can use AI-enhanced coding tools to help them write new malware, modify existing application code to perform malicious activities, or to find vulnerabilities in large code bases.

Learning Objective 1.4.B: Explain how to protect against some AI-augmented cyberattacks.

• 1.4.B.1 Shared secrets with close friends and relatives that can be used to verify each other’s identities should be established. A secret word or phrase known only to two parties can be used to authenticate identities in high-stakes situations.
• 1.4.B.2 Multifactor authentication (MFA) should be enabled. If an adversary clones a target’s voice to access a system with voice authentication, requiring a second authentication factor could prevent an adversary from gaining access to accounts.
• 1.4.B.3 Personal or sensitive data should not be entered into any AI-powered tools, such as chatbots or virtual assistants. Some AI-powered tools feed user input back into the model to provide continuous training. Adversaries could extract data that users have included in prompts.
• 1.4.B.4 Output from AI-powered tools should be carefully evaluated. Verify information from AI-powered tools using reputable, stable, non-AI-based sources.

Learning Objective 1.5.A: Explain how cyber defenders can leverage AI-powered tools to protect networks, applications, and data.

• 1.5.A.1 AI tools can review current security configurations, like firewall rules and access controls, and recommend more secure options. Recommendations should always be checked by a knowledgeable security technician before being implemented.
• 1.5.A.2 AI-powered tools can analyze application code to identify vulnerabilities and recommend mitigations. Recommendations should always be reviewed by a knowledgeable programmer before being implemented.
• 1.5.A.3 AI-powered tools can suggest rules for automated detection systems. Detection rules should always be reviewed by a knowledgeable detection engineer before being added to a system.

Learning Objective 1.5.B: Explain how AI-powered tools are enabling faster and more accurate threat detection and response.

• 1.5.B.1 Of the millions of digital events that happen on networks daily, some likely represent an adversary conducting malicious activity. Humans cannot carefully examine all those events to identify the malicious activity.
• 1.5.B.2 AI-powered tools can be trained to quickly analyze digital events and sort the events that are likely malicious activity from those that are harmless.
• 1.5.B.3 AI-powered tools can be programmed to alert human cybersecurity personnel when likely malicious activity is detected or to take specific corrective actions based on the type of malicious activity detected.
• 1.5.B.4 AI-powered tools enable threat-detection and response teams to catch malicious activity and intervene quickly to prevent loss, harm, damage, and destruction to digital infrastructure and data.

Learning Objective 2.3.A: Identify managerial controls related to physical security.

• 2.3.A.1 Organizations should conduct employee security awareness training to educate employees about how they can contribute to the organization’s security by:
  • Detecting social engineering attempts like phishing
  • Not badging other people into restricted areas
  • Preventing device theft
• 2.3.A.2 Organizations should have a workstation security policy that outlines the measures necessary to protect a physical workplace. The policy may have tiers of workstation security based on the type of data handled at a workstation. Workstation policies often require:
  • Locking devices before leaving workstations unattended to prevent unauthorized access
  • Clearing sensitive documents off workstations before leaving them unattended (sometimes called a clean desk policy)
  • Using a privacy screen filter or other physical barrier to prevent others from viewing information on the screen
  • Connecting devices to surge protectors or uninterruptible power supplies (UPS)

Learning Objective 2.3.B: Determine mitigation strategies for risks from physical vulnerabilities.

• 2.3.B.1 To determine a relevant control, a cyber defender considers how an adversary could take advantage of a vulnerability to attack a system and how to prevent, detect, or correct the attack.
• 2.3.B.2 Installing physical controls like fencing, gates, and bollards around a building can deter adversaries from trying to physically access an organization’s buildings.
• 2.3.B.3 Locks on doors, server cabinets, and computers can prevent devices from being accessed or stolen.
• 2.3.B.4 Card readers can record which employee badges are being used to access different entries at specific times and deny access to unauthorized badges.
• 2.3.B.5 Access control vestibules and turnstiles can prevent an authorized person from intentionally or accidentally admitting an unauthorized person into a restricted area.
• 2.3.B.6 Organizations can disable USB ports to prevent external drives from loading malware onto a computer.
• 2.3.B.7 An uninterruptible power supply (UPS) provides a backup power source for a device in the event of a power outage. Organizations can also use power generators to provide power at a larger scale to a building or set of critical devices.
• 2.3.B.8 Organizations prioritize risk mitigations based on the severity of the risks and the cost of the recommended mitigations.

Learning Objective 2.4.A: Identify ways security controls can detect physical attacks.

• 2.4.A.1 Cameras can capture a visual record of an adversary’s malicious activity. The feed from a camera should be recorded and monitored for maximum effect. Recordings can be especially helpful in after-incident investigations.
• 2.4.A.2 Security guards can monitor activity in an area and respond to suspicious activity once detected.
• 2.4.A.3 Motion sensors can alert security to movement in an area.
• 2.4.A.4 Employees that work in a physical space are often the first to notice the presence of an unauthorized person and can alert security.

Learning Objective 2.4.B: Determine effective placement of security controls for detecting physical attacks.

• 2.4.B.1 When placing cameras, consideration should be given to visual coverage, angle, and the ability to be tampered with by an adversary. Consideration should also be given to what a camera in a specific area could capture an adversary doing and how that information would be helpful. Points of ingress and egress are often monitored by camera.
• 2.4.B.2 Motion sensors should be placed in areas where traffic is unexpected, like server rooms, or areas where sensitive materials are stored and few people have access. Motion sensors in high-traffic areas create many false alarms, making the alarms less likely to be taken seriously when there is a real security event.
• 2.4.B.3 Locks should be placed on all entries to areas containing sensitive information or systems. For areas with particularly sensitive information or systems, an organization could use an access control vestibule at the entry point to prevent piggybacking or tailgating.
• 2.4.B.4 Security guards can be stationary or patrolling. Stationary guards can provide constant protection for a specific area, entrance, or high-value item. Patrolling guards are more difficult for an adversary to plan around and can create time pressure for an adversary. Placing stationary guards at places that funnel traffic (e.g., entry gates, main entrances or lobbies, and entrances to more secure access areas) can be highly effective, while patrolling guards are better suited for perimeters and exterior areas.

Learning Objective 2.4.C: Apply detection techniques to identify physical attacks.

• 2.4.C.1 Cameras provide visual monitoring and a visual record of activity within a designated space. Cameras can be paired with facial recognition software that can provide alerts when unauthorized individuals enter controlled areas. Once a physical breach has been detected, defenders can use live and recorded camera footage to track an adversary’s path and actions.
• 2.4.C.2 Motion detectors work best when paired with cameras. When a security alert is raised because a motion detector has been activated, defenders can use cameras to check the space visually and verify a physical security breach.
• 2.4.C.3 When employees are required to use an electronic badge to unlock a door to a restricted area, a sensor can record how long the door was open. In reviewing entry logs for the door, potential piggybacking or tailgating can be detected by doors being open for longer than normal lengths of time.

Learning Objective 3.1.A: Identify common network attacks.

• 3.1.A.1 The address resolution protocol (ARP) is used by a default gateway on a network to establish a table that pairs internet protocol (IP) addresses with media access control (MAC) addresses. An ARP poisoning attack is when an adversary sends falsified ARP packets to the default gateway to modify the table so that the adversary’s device receives traffic intended for the target by linking the target’s IP address to the adversary’s MAC address. Faking a MAC address is called MAC spoofing. This is an example of an on-path attack (or man-in-the-middle attack), which is when an adversary interrupts a data stream between two parties, captures both parties’ data, and copies or alters the data before sending them on. Both parties think they are communicating directly with each other, but instead they are each communicating with the adversary who is secretly intercepting their messages.
• 3.1.A.2 A MAC flooding attack is when an adversary sends the target switch many Ethernet frames, each with a different MAC address. This can force the switch into broadcast mode, and the adversary can then collect all of the frames on the network (because they are being broadcast), which could allow the adversary to access sensitive information. This is an example of eavesdropping (or sniffing), which is when an adversary captures data in transit and can record and copy the data.
• 3.1.A.3 A domain name system (DNS) poisoning attack is when an adversary pretends to be an authoritative name server (NS) and plants a fake DNS record on a DNS server to redirect browser traffic to a malicious website designed to steal credentials. This is an example of credential harvesting, which is when adversaries set up a fake login site that looks like a real one. Unsuspecting users enter their real credentials, which the adversaries capture and use.
• 3.1.A.4 A smurf attack attempts to overwhelm a network with Internet Control Message Protocol (ICMP) requests. It is a type of denial of service (DoS) attack, which makes a system or resource unavailable to authorized users. During a smurf attack, an adversary sends many ICMP requests with the victim’s address to the network’s broadcast address. The network’s gateway then sends these requests to all devices on the network. Each device on the network replies to the victim’s address, creating a flood of traffic that can block legitimate messages. When multiple devices attack the same target simultaneously, it’s called a distributed denial of service (DDoS) attack.

Learning Objective 3.1.B: Explain how adversaries can exploit network vulnerabilities to steal, disrupt, or destroy network communication.

• 3.1.B.1 Adversaries can send malicious traffic into a network to flood it creating a DoS, to map the internal structure of the network, or to spoof a legitimate device. Networks without firewalls, or with improperly configured firewalls, are vulnerable to these types of attacks.
• 3.1.B.2 Adversaries that have compromised a device often attempt to leverage their access to compromise other devices on the local area network (LAN).
• 3.1.B.3 Adversaries that physically plug into a data port can gain access to a LAN through the switch port unless port security is enabled. This allows adversaries to launch DoS attacks or perform MAC flooding or MAC spoofing attacks.
• 3.1.B.4 Adversaries standing outside of physically secure spaces can pick up the signals and beacon frames from a wireless access point that is broadcasting outside the physical space. This allows them to gather information about the wireless network and to attempt eavesdropping and cryptographic attacks on it.
• 3.1.B.5 Adversaries can attempt to join networks to launch attacks from within the networks. Networks that do not authenticate devices and users make it easier for adversaries to join.
• 3.1.B.6 If there is an open network port, an adversary can plug a wireless access point into the port creating a rogue access point. The adversary could use this rogue access point to access the internal network wirelessly (maybe even from outside the physical space). This allows the adversary direct access to the LAN, bypassing any firewalls.
• 3.1.B.7 Adversaries can attempt to break wireless encryption and intercept, steal, or compromise data on a network.

Learning Objective 3.1.C: Assess and document risks from network vulnerabilities.

• 3.1.C.1 Vulnerabilities on a network can lead to adversaries being able to intercept and alter data in transit, launch DoS attacks, or move laterally on a network to gain access to more sensitive or critical systems. Network vulnerabilities can constitute a risk to confidentiality, integrity, and availability.
• 3.1.C.2 There are automated vulnerability scanners that can check networks, devices, and applications for known vulnerabilities. These scanners produce a report that often includes the vulnerabilities detected, their severity, and mitigation recommendations.
• 3.1.C.3 Successfully exploiting a network vulnerability often requires advanced technical ability and knowledge. This can impact the likelihood of an exploit.
• 3.1.C.4 High risks from network vulnerabilities allow an adversary to easily have a significant impact by capturing network traffic, spoofing a legitimate device on the network, or launching a DoS attack.
  • Illustrative examples for 3.1.C.4:
    • An organization has a single unsegmented internal network that is accessible via a wireless network with weak encryption, and on that network it has a server running its proprietary web-application.
• 3.1.C.5 Moderate risks from network vulnerabilities could include vulnerabilities that might give adversaries the ability to gain information about systems or devices on a network.
  • Illustrative examples for 3.1.C.5:
    • An organization’s external firewall is not configured to block external ICMP traffic.
• 3.1.C.6 Low risks from network vulnerabilities include vulnerabilities that would be difficult to exploit and would likely have minimal negative impacts on an organization.
  • Illustrative examples for 3.1.C.6:
    • An organization has wireless access points that broadcast a beacon frame, which contains the network service set identifier (SSID) and the wireless encryption protocols.

Learning Objective 3.2.A: Identify managerial controls related to network security.

• 3.2.A.1 A router security policy will set forth a minimum configuration standard for routers on an organization’s network and may include:
  • Banning local user accounts (All router logins must use an approved authentication server.)
  • Disabling unnecessary services (e.g., Telnet)
  • Requiring a firewall (An organization may opt for a firewall device separate from the router.)
• 3.2.A.2 A switch security policy will set forth a minimum configuration standard for switches on an organization’s network and may include:
  • Banning local user accounts (All switch logins must use an approved authentication server.)
  • Requiring port security to be enabled.
  • Using MAC filtering
• 3.2.A.3 A virtual private network (VPN) policy will detail the minimum security requirements for employees using a VPN to access an organization’s internal network, and it may include:
  • A list of roles within the organization that are allowed to use a VPN to access the organization’s internal network
  • Authentication requirements for employees using a VPN (e.g., public/private key system or MFA)
  • A prohibition against split tunneling (also called dual tunneling)
• 3.2.A.4 A wireless security policy will establish the minimum security requirements for wireless networks within an organization and may include:
  • Requiring users to authenticate to the wireless network through an extensible authentication protocol (EAP) connected to an approved authentication server
  • Requiring all wireless traffic to be encrypted using AES encryption with a minimum key length
  • Disabling beacon frames on wireless access points

Learning Objective 3.2.B: Configure wireless network security features.

• 3.2.B.1 Organizations can disable beacon frame broadcasting on wireless access points (WAPs) to make it harder for adversaries to find their wireless network and learn its basic properties.
• 3.2.B.2 Organizations can control the broadcast direction and signal strength of a WAP so the signal does not extend beyond the physical space the access point is meant to cover.
• 3.2.B.3 Organizations should enable strong wireless encryption protocols to ensure wireless frames are not readable by adversaries who might intercept them.
  • WEP, WPS, and the original WPA wireless encryption protocols have known vulnerabilities and are insecure.
  • WPA3 is currently the strongest wireless encryption algorithm.
• 3.2.B.4 Organizations can enable MAC filtering to prevent unauthorized devices from accessing the network, and they can require users to authenticate when joining a network.

Learning Objective 3.3.A: Identify techniques for segmenting a network.

• 3.3.A.1 Firewall zones and rules can be used to create a screened subnet (also known as a demilitarized zone, or DMZ)—a network segment that sits between public, external networks like the internet and internal, private networks. A screened subnet is typically a lower security zone than the internal, private networks, and it typically holds an organization’s publicly facing resources, separating them from the internal network.
• 3.3.A.2 Subnetting can be used to create different subnets based on IP addressing. If a device is compromised by an adversary, subnets can contain a security breach to reduce the number of exposed devices.
• 3.3.A.3 Switches can be used to create VLANs, which logically separate devices physically connected to central switches.

Learning Objective 3.3.B: Explain why network segmentation can increase network security.

• 3.3.B.1 Network segmentation refers to the process of dividing a network into smaller, isolated segments or subnetworks (subnets).
• 3.3.B.2 Dividing a network into smaller subnets isolates network traffic, which can prevent attacks on one subnet from impacting devices on other subnets.
• 3.3.B.3 Network segmentation can allow for different security policies and controls to be applied to different segments of the network, allowing for higher security zones and lower security zones.
• 3.3.B.4 Port security on a switch can prevent MAC flooding by limiting the number of addresses assignable to any single switch port.

Learning Objective 3.4.A: Identify types of network-based firewalls.

• 3.4.A.1 A firewall is used to allow or deny network traffic in or out of a network. The firewall itself is software that can be hosted on a standalone device or integrated into another network device, such as a router.
• 3.4.A.2 A stateless firewall filters traffic based on information in packet headers, such as IP addresses, ports, and protocols.
• 3.4.A.3 A stateful firewall (also known as dynamic packet filtering) tracks the state of network connections passing through the firewall and can filter according to connection-related rules in addition to the filtering done by a stateless firewall. This allows for more control over content allowed in and out of a network.
• 3.4.A.4 A next-generation firewall (NGFW) has both the capabilities of typical stateless and stateful firewalls and additional advanced features, such as intrusion prevention, deep packet inspection, and filtering by application type.

Learning Objective 3.4.B: Explain how a firewall uses an access control list to allow or deny traffic entering or leaving a network.

• 3.4.B.1 Network administrators create a set of rules, called an access control list (ACL), that a firewall uses to permit or deny inbound and outbound network traffic.
• 3.4.B.2 ACL rules are checked in order and the first rule that matches the criteria will be executed for the specified data.
• 3.4.B.3 A typical ACL will specify the direction of traffic (inbound or outbound), the criterion to filter by (IP addresses, logical port, service, or application), and the action to take (permit or deny).

Learning Objective 3.4.C: Determine the effective placement of firewalls in a network.

• 3.4.C.1 Each segment of a network should have a firewall to control the flow of data in and out of that segment.
• 3.4.C.2 Network segments may have different security needs based on the data and services within them. The level of security for each firewall can be set independently.
• 3.4.C.3 Each point of data ingress and egress between the internal network and the public internet should have a firewall.

Learning Objective 3.4.D: Configure a firewall to manage the flow of network traffic.

• 3.4.D.1 The requirements for a firewall will specify what type of traffic from which sources or to which destinations should be allowed or denied.
• 3.4.D.2 Specific rules for a firewall can allow or deny inbound or outbound traffic based on source or destination port or IP address, service, protocol, or application.
  • Illustrative examples for 3.4.D.2:
    • Allow inbound TCP port 22 from ALL; (this rule will allow all inbound TCP traffic with destination port 22, which is the designated port for the SSH protocol)
    • Deny inbound TCP port 80 from 192.168.1.0/24; (this rule will deny inbound TCP traffic with destination port 80 from IP addresses in the 192.168.1.0-192.168.1.255 range)
• 3.4.D.3 Rules are implemented in order, and changing the order of a set of rules can change which traffic is allowed or denied. Consideration must be given to the precedence of filtering priorities when establishing the order of rules.
  • Illustrative examples for 3.4.D.3:
    • This set of rules would allow SSH traffic and deny other inbound TCP traffic
    • Rule 1: ALLOW inbound TCP port 22 from ALL;
    • Rule 2: DENY inbound TCP ALL from ALL;
    • Reversing the order of those rules would deny all inbound TCP traffic including SSH traffic.

Learning Objective 3.5.A: Identify types of automated security tools used to detect network attacks.

• 3.5.A.1 Automated detection tools analyze data collected from an organization’s network and devices, such as switches and routers, servers, firewalls, and user computers. These data are often collected in a log file.
• 3.5.A.2 A network intrusion detection system (NIDS) is an automated tool that analyzes data to determine if malicious activity is taking place on a network. When an attack is detected, it generates an alert.
• 3.5.A.3 A network intrusion prevention system (NIPS) is an automated tool that, like an IDS, analyzes data to determine if malicious activity is taking place on a network. A NIPS can also mitigate or halt an attack by closing ports, blocking specific IP or MAC addresses, or rejecting specific protocols.
• 3.5.A.4 A security information and event management (SIEM) system collects and analyzes data from multiple sources (including firewalls, NIDS/NIPS, device logs, and application logs) to detect patterns that may indicate a cyberattack and raises an alert if a potential attack is detected. Security analysts investigate the alert to determine whether it represents a true threat and follow standard operating procedures to resolve or escalate the alert.

Learning Objective 3.5.B: Explain how organizations can leverage artificial intelligence (AI) to enhance threat detection and response.

• 3.5.B.1 Computers log every action that users take. Firewalls, IDS, IPS, and other network sensors log all the traffic passing through various points in a network. A medium-sized organization’s network is logging millions (or even tens of millions) of data points per day. Even a large team of humans is incapable of analyzing so much data.
• 3.5.B.2 Threat detection teams are creating AI algorithms to analyze large amounts of data and classify the data patterns as malicious or normal.
• 3.5.B.3 AI models for threat detection are based on probabilistic calculations; they report a percentage to indicate the likelihood that something is malicious.
• 3.5.B.4 Organizations determine their own thresholds for what percentage of likelihood of a threat results in an alert. If the threshold is set too high, real attacks may go undetected; if the threshold is too low, the security team will be overwhelmed with false alerts.

Learning Objective 3.5.C: Determine a network detection method.

• 3.5.C.1 Volume of network traffic is a criterion for determining a detection method. Signature-based detection is more efficient for networks with high traffic volume. Signature-based detection compares detection data to a database of known indicators of compromise (IoCs), called signatures. Signature databases must be updated with IoCs for the latest attacks. Signature-based detection runs more quickly than anomaly-based detection.
• 3.5.C.2 Consistency of network traffic patterns is a criterion for determining a detection method. Anomaly-based detection is most effective on networks with consistent traffic patterns. Anomaly-based detection compares detection data to a baseline of recorded activity. Baselines must be recorded on uncompromised systems to establish expected data types and volumes. Anomaly-based detection triggers an alert or action when data types or volumes outside of a specified tolerance range are recorded. Anomaly-based detection relies on consistent patterns in network traffic to detect anomalous traffic patterns.
• 3.5.C.3 Degree of sensitivity or criticality of a network is a criterion for determining a detection method. Networks with more sensitive or critical data or services will likely consider a hybrid approach. Hybrid detection combines signature-based and anomaly-based detection. Hybrid detection is more expensive than using either signature- or anomaly-based detection alone, and hybrid-detection models generate more alerts.
• 3.5.C.4 Likelihood of novel attacks on a network is a criterion for determining a detection method. Signature-based detection cannot detect a new attack. When an organization suspects that adversaries are likely to attempt a new attack on a network, anomaly-based detection is the preferred method when the cost of hybrid detection is prohibitively high.

Learning Objective 3.5.D: Evaluate the impact of a network detection method.

• 3.5.D.1 Speed of detection is a factor in evaluating the impact of a network detection method. Faster detection enables faster response. Signature-based detection methods are faster than anomaly-based detection methods, especially on networks with high traffic volume.
• 3.5.D.2 Cost is a factor in evaluating the impact of a network detection method. Detection tools and ongoing costs need to be within a budget. Anomaly-based detection systems require more expensive hardware to operate than signature based. Hybrid detection is the most expensive option because it combines both anomaly- and signature-based methods.
• 3.5.D.3 False positive rate is a factor in evaluating the impact of a network detection method. Signature-based detection has almost no false positives. Anomaly-based or hybrid detection will have higher false positive rates. Impacts of high false positive rates include:
  • Time and resources are put toward investigating alerts for nonmalicious activity.
  • Alert fatigue is a condition that occurs when responders get accustomed to false positives and take alerts less seriously because they assume alerts are false positives before investigating them.
• 3.5.D.4 False negative rate is a factor in evaluating the impact of a network detection method. A false negative occurs when an adversary can bypass a detection system. Signature-based detection systems are easier to bypass than anomaly-based or hybrid systems. False negatives can result in adversaries causing loss, harm, disruption, or destruction to data and systems.

Learning Objective 3.5.E: Apply detection techniques to identify indicators of network attacks by analyzing log files.

• 3.5.E.1 Evil-twin attacks can be detected by regularly scanning for service set identifiers (SSIDs) that look suspicious or similar to local legitimate SSIDs. Signal triangulation can be used to locate and disable an access point broadcasting an evil-twin network.
• 3.5.E.2 Jamming attacks can be detected by recognizing that no wireless devices in a specific physical space are able to connect to a wireless network and by scanning for electromagnetic (EM) noise in the wireless range.
• 3.5.E.3 ARP poisoning attacks can be detected by monitoring network traffic for unusual ARP messages (particularly duplicate MAC address ARP packets) and checking the ARP table on the default gateway.
• 3.5.E.4 MAC flooding attacks can be detected by monitoring network traffic for an unexpected surge of Ethernet frames with different MAC addresses and checking the MAC address table on a switch.
• 3.5.E.5 DNS poisoning attacks are difficult to detect. However, if an organization’s website experiences an abrupt and otherwise inexplicable drop in traffic, DNS records should be examined as a potential cause.
• 3.5.E.6 Smurf attacks can be detected by watching network traffic for a sudden increase in ICMP requests sent to the network’s broadcast address.
• 3.5.E.7 Network-based IoCs are discovered when analyzing network traffic, often in the form of packet capture files. Indicators can be found in source and destination IP addresses, ports, and protocols. These can include:
  • Connections to known malicious IP addresses
  • Unauthorized network scans
  • Unusual spikes or slow downs in network traffic
  • Mismatched port-application traffic

Learning Objective 4.1.A: Identify types of computing devices.

• 4.1.A.1 Server computers are devices that provide one or more services to other computers (e.g., DNS, DHCP, FTP). Any computer can be a server, and in an enterprise environment servers typically have more processing power and storage than a personal computer.
• 4.1.A.2 Personal computers are devices that are designed to be used by one person for work or recreational purposes (e.g., word processing, graphic design, web browsing, and media production or viewing). These include desktop, laptop, and notebook computers.
• 4.1.A.3 Handheld computers (also called mobile computers or information appliances) are smaller than personal computers and run on battery power. These include tablets, smartphones, and wearable technology like smart watches.
• 4.1.A.4 Embedded computers are devices that are part of a machine. Embedded devices have specific instruction sets for interfacing with the specialized components of the machine they’re embedded in. Embedded computers tend to be slower and cheaper than other computers and have minimal storage.
• 4.1.A.5 Everyday devices with embedded computers are often called Internet of Things (IoT) devices. Embedded computers are found in transportation (e.g., cars, trains, and airplanes), devices that operate critical infrastructure (e.g., operating circuit breakers at electrical substations and pumps at water treatment plants), medical equipment (e.g., IV pumps, MRI scanners, pacemakers, and insulin pumps), and everyday devices like washing machines, coffee makers, and thermostats.

Learning Objective 4.1.B: Identify the type of malware used in a cyberattack.

• 4.1.B.1 Malware is malicious software that can damage or destroy a device or network, or allow an adversary access to a device and the data on the device.
• 4.1.B.2 Malware is often used as a tool to accomplish part of an adversary’s plan to achieve their ultimate goal(s). There are many types of malware, such as:
  • Viruses are malware that must be activated by a user executing or opening a file.
  • Worms spread from one computer to another without human interaction.
  • Trojans are malware embedded in other software that seems harmless. Remote access trojans (RATs) provide an adversary with remote access to the target system.
  • Ransomware encrypts a device’s files, preventing the user from accessing files on the device. The ransomware typically presents the user with a screen demanding payment and promising to give the user a decryption key for their files if the user pays within a fixed amount of time.
  • Spyware tracks a user’s actions on a computer and sends information back to an adversary.
  • A keylogger is software or hardware that logs the users keystrokes and sends the information back to the adversary. Adversaries can often extract usernames and passwords from keylogger data.
  • Logic bombs are set to trigger their effect only when a specific set of conditions are met; the conditions can include time and date, specific type or version of the operating system, character set the computer is using, etc.
  • A rootkit is sophisticated malware that gets into the target computer’s operating system and can control nearly every aspect of the system, including making the rootkit itself invisible to detection.
• 4.1.B.3 While most malware is a file or a collection of files, fileless malware is malicious code that lives in RAM and uses legitimate programs already installed on a device to compromise it.

Learning Objective 4.1.C: Explain how adversaries can exploit common device vulnerabilities to cause loss, damage, disruption, or destruction.

• 4.1.C.1 Adversaries can develop exploits for known vulnerabilities in software (including operating systems). Devices with unpatched software are vulnerable to these exploits, which could allow an adversary to crash a system, view user actions, enable or disable various services or components on the device (e.g., turning on a webcam or microphone), or even take control of the device to issue their own commands including commands to steal or destroy information on the device.
• 4.1.C.2 Adversaries can take advantage of weak authentication requirements by guessing a user’s password or using social engineering to get a user to divulge their password.
• 4.1.C.3 When systems don’t have a password on the basic input output system (BIOS) or unified extensible firmware interface (UEFI), an adversary can boot a computer into a special mode (e.g., “recovery mode”) that gives them higher-level privileges. Without BIOS or UEFI protection, adversaries can load their own operating system onto a device from an external drive and use specialized tools to alter or create user profiles, including changing user passwords.
• 4.1.C.4 Adversaries can load malware onto an external drive, and if autorun is enabled, then a device will run the malware when the external drive is inserted.
• 4.1.C.5 Adversaries can leverage open ports to connect to a device.
• 4.1.C.6 Adversaries can send malicious data to devices to disrupt them or attempt to take control of them. Devices that have no firewall (or a misconfigured firewall) cannot filter out this malicious data.
• 4.1.C.7 Adversaries often attempt to install malware on a device to disrupt or control it. Devices lacking anti-malware software are more vulnerable to this type of attack.

Learning Objective 4.1.D: Assess and document risks from device vulnerabilities.

• 4.1.D.1 Risk from device vulnerabilities can come from unauthorized access or malware that allow an adversary to impersonate an authorized user, remotely control a device, encrypt a device’s drive to ransom the data, or wipe a device’s memory, destroying data or rendering the device inoperable. The level of risk varies depending on the criticality of the device or the services the device provides or data it stores.
• 4.1.D.2 High risks from device vulnerabilities involve potentially compromising sensitive data or critical operations.
  • Illustrative examples for 4.1.D.2:
    • An organization has not installed the most recent update for their email server which included a patch for a known critical vulnerability.
• 4.1.D.3 Moderate risks from device vulnerabilities can arise from weak authentication requirements or from vulnerabilities that would be less likely to be exploited.
  • Illustrative examples for 4.1.D.3:
    • A water treatment plant has embedded systems controlling pumps. The pumps can be remotely accessed via username and password for remote management for the plant, but the devices do not require multi-factor authentication (MFA).
• 4.1.D.4 Low risks from device vulnerabilities are typically related to vulnerabilities that, if exploited, would have little impact.
  • Illustrative examples for 4.1.D.4:
    • An employee’s laptop has telnet port 23 open.

Learning Objective 4.3.A: Identify managerial controls related to device security.

• 4.3.A.1 An acceptable use policy will describe the range of activities that are permissible, prohibited, or required by users on devices owned by an organization and may include:
  • Prohibiting users from accessing specific websites or types of websites (e.g., social media or gaming)
  • Requiring users to keep software updated
  • Allowing users to connect peripheral devices
  • Prohibiting users from connecting external drives or media
• 4.3.A.2 A password policy will detail the requirements for user passwords within an organization and may include:
  • A minimum or maximum password length
  • A minimum or maximum amount of time a user may keep the same password
  • A prohibition of password reuse
  • Rules for password construction (e.g., no dictionary words and character set requirements)
  • A suggestion to use secure password management tools instead of writing passwords down
• 4.3.A.3 A software installation policy will describe what (if any) software users are allowed to install on their devices and usually also a process for users to request specialized software they may need to perform their role, and it may include:
  • A prohibition against users installing software on their devices
  • A process for users to request new software needed for their role
  • A list of approved software for users

Learning Objective 4.3.B: Explain how anti-malware software can make a device more secure.

• 4.3.B.1 Anti-malware software (sometimes called antivirus software) has tools to quarantine and remove malware that can corrupt, spy on, or destroy a system. Malware contains indicators that make it detectable; these indicators are called signatures.
• 4.3.B.2 Anti-malware software has a database of malware signatures. It periodically scans the files on a device and checks to see if any of the files match any of the signatures in its database. If there is a match, the software quarantines and removes the malicious files.

Learning Objective 4.3.C: Explain why keeping a device’s operating system and software updated makes it more secure.

• 4.3.C.1 When vulnerabilities in operating systems and software are found, the vendor or organization that maintains the operating system software will fix it and send an update. A small update is called a patch.
• 4.3.C.2 Ensuring that a computer’s operating system and software applications are updated to the most recent version prevents adversaries from taking advantage of a known vulnerability.

Learning Objective 4.3.D: Configure a host-based firewall.

• 4.3.D.1 Host-based firewalls allow or deny traffic into or out of a single device. This provides an extra layer of security in case a host is connected to a compromised network.
• 4.3.D.2 A host-based firewall is software that runs on a device and follows a set of rules (an ACL) like a network-based firewall. Firewall rules are implemented in order, applying the first rule that matches.
• 4.3.D.3 A host-based firewall can also block specified types of outbound traffic. Host-based firewalls should always block ports or services not needed for a given device.
  • Illustrative examples for 4.3.D.3:
    • A host-based firewall is configured to block outbound FTP traffic. This prevents an adversary with remote access to the host from using FTP to exfiltrate a file to the adversary’s server.
• 4.3.D.4 The rules for a host-based firewall can allow or deny traffic based on source or destination port or IP address, service, protocol, or application.

Learning Objective 4.4.A: Explain how to detect attacks against devices.

• 4.4.A.1 System processes and settings, login attempts, file download attempts, and user actions are logged by computing systems. These logs can be used to reconstruct circumstances leading up to and during a cyber incident.
• 4.4.A.2 An indicator of compromise (IoC) is evidence that an adversary has compromised a device or network.
• 4.4.A.3 Authentication logs (or auth logs) record every attempted login on a system. Analysis of authentication logs can reveal attempted attacks.
• 4.4.A.4 Host-based IoCs are discovered when analyzing logs and configuration settings. Indicators, such as the following, can be found in authentication logs, user activity logs, and system configuration files:
  • Unusual files being created or modified
  • Unexpected processes or services
  • Unauthorized changes to system configuration settings
  • Unauthorized software installation or update
• 4.4.A.5 File-based IoCs are discovered when analyzing files on a device. Indicators are usually found in executable files and can include:
  • Files whose hash matches known malware
  • File names that are known to be created by a certain piece of malware
  • File paths that are associated with malicious activity
• 4.4.A.6 Behavior-based IoCs are discovered when analyzing logs. Indicators can be found in authentication logs and access logs and can include:
  • Multiple failed login attempts
  • Unusual login times or locations
  • Unauthorized attempts to access sensitive data
  • Attempts to elevate user privileges on a system

Learning Objective 4.4.B: Determine controls for detecting attacks against a device.

• 4.4.B.1 Performance is a criterion for determining a detection method. Detection tools use system memory and processing power and can impact the performance of a device. Anomaly-based detection tools use more system resources than signature-based tools. Signature-based detection is a better option for devices with less powerful system resources. Many embedded devices do not have enough system resources to run any detection tools on the device.
• 4.4.B.2 Cost is a criterion for determining a detection method. Organizations that purchase detection software need to consider the cost of purchasing enough software licenses for the number of devices they need to monitor. Some organizations purchase an endpoint detection and response (EDR) service from a third-party vendor. Although these services are expensive, they provide a holistic, unified approach to threat detection for an organization’s devices; they typically include a centralized alert platform for monitoring possible attacks on devices.
• 4.4.B.3 Sensitivity or criticality of the device is a criterion for determining a detection method. Devices that store or process sensitive information or provide critical services are more likely to be targeted by adversaries and benefit from a hybrid-detection model to offer maximum protection, when possible.

Learning Objective 4.4.C: Evaluate the impact of a device detection method.

• 4.4.C.1 Speed and performance are factors in evaluating the impact of a detection method. Signature-based detection is faster than anomaly-based detection in general, and that effect is compounded on devices, which often lack the processing power to effectively run anomaly-based detection tools. Implementing resource-intensive detection tools on devices can degrade device performance.
• 4.4.C.2 Phase of the attack is a factor in evaluating the impact of a detection method. To carry out actions on a device, adversaries must first bypass a combination of physical- or network-layer protective, deterrent, and detective security controls. Detecting and stopping an attack at the device level can prevent adversaries from accessing sensitive data or disrupting critical services.
• 4.4.C.3 False positives versus ease of bypassing detection is a factor in evaluating the impact of a detection method. Most device-level detection tools are signature-based, and signature-based detection has a low rate of false positives. However, signature-based detection is easier for adversaries to bypass.

Learning Objective 4.4.D: Apply detection techniques to identify indicators of password attacks by analyzing log files.

• 4.4.D.1 Online password attacks can be detected in authentication logs. A single user attempting many wrong passwords is an indicator of an online password attack. If a user:password hash database has been compromised, all the user passwords in the database should be considered insecure and all users should be forced to reset their passwords.
• 4.4.D.2 If an authorized user is logging in from a different location or IP address than expected, or at a different time than normal, this can be an indicator that the user’s password has been compromised.
• 4.4.D.3 An indicator of password spraying is many users trying to log in within seconds of each other from one IP address or from unusual IP addresses.
• 4.4.D.4 An indicator of credential stuffing is a series of default user:password combinations being attempted on a device in quick succession, often from the same IP address.
• 4.4.D.5 Offline password attacks can’t be detected, because the attack takes place on the adversary’s computer.

Learning Objective 5.2.A: Explain how the state or classification of data impacts the type and degree of security applied to that data.

• 5.2.A.1 Organizations implement specific security controls to comply with legal requirements based on the types of data they collect, store, process, and transmit.
• 5.2.A.2 Data can be classified by their state.
  • Data at rest are stored on a drive. It is important to protect the physical drive storing the data from destruction or theft. Data at rest can also be encrypted so that if an adversary steals it, they can’t immediately read the data.
  • Data in transit are being sent from one device to another. If the data are being transferred over physical media (e.g., cables) it is important to protect the media. Data in transit can also be encrypted so that if an adversary intercepts it, they can’t immediately read the data.
  • Data in use are being processed by software or a person. Access controls can be used to limit who or what has the ability to use data in different ways (e.g., view or edit). Data must be unencrypted to be used.
• 5.2.A.3 Organizations often categorize data according to their sensitivity and prioritize a higher degree of security for more sensitive information.
• 5.2.A.4 Laws and regulations can require certain types of data to be stored, transmitted, and handled according to specific rules.
  • Personally identifiable information (PII) is any data that allows someone to be identified and includes (but is not limited to): name, signature, phone number, address, biometric data (e.g., fingerprints), social security number, date of birth, and email address. The protection of this data is covered by many laws but most notably The Privacy Act of 1974 and for children under the age of 13 the Children’s Online Privacy Protection Act of 1998.
  • Protected health information (PHI) is any data related to an individual’s health, treatment, payment for healthcare at any time and includes (but is not limited to): test results, treatment records, hospital records, doctor visit notes, and health provider payment records. The protection of PHI is included in the Health Insurance Portability and Accountability Act of 1996.
  • Payment card information (PCI) is the data collected by organizations to process payments via cards (e.g., credit cards) and includes the following: name, account number, expiration date, address, and CVV code. The protection of this data is regulated by the Payment Card Industry Data Security Standard (PCI-DSS).
• 5.2.A.5 Organizations that collect regulated data will label them and have policies that comply with the legal or regulatory requirements for the safe storage, transmission, and handling of these data.

Learning Objective 5.2.B: Identify managerial controls related to application and data security.

• 5.2.B.1 A cryptography policy will describe the acceptable encryption protocols and key parameters for an organization and may include:
  • A list of encryption algorithms approved for specific uses
  • Minimum or maximum key lengths
  • Cryptographic key-generation requirements and parameters
  • Cryptographic key-storage requirements
• 5.2.B.2 A web application security policy will outline the requirements and parameters for testing and mitigating web application vulnerabilities in an organization, and it may include:
  • Parameters for when an application is subject to a security assessment
  • Timelines for remediating vulnerabilities based on level of risk
  • Parameters for how an application security assessment is to be carried out (e.g., using specific tools or according to specific frameworks)

Learning Objective 5.2.C: Determine an appropriate access control model to protect applications and data.

• 5.2.C.1 Access control enforces which users or applications (called subjects) can access, modify, add, or remove (called operations) which files or applications (called objects). Access control models describe how to determine which subjects have what type of access to which objects.
• 5.2.C.2 Role-based access control (RBAC) assigns every subject to a role and defines which roles have which types of access to which objects.
  • Illustrative examples for 5.2.C.2:
    • An example of a role at a company might be “accountant,” and one type of object could be the payroll software. Role-based access could be used to ensure that only subjects who are assigned to the role of “accountant” have access to the payroll software object.
• 5.2.C.3 Rule-based access control (RuBAC) checks a set of rules to determine what type of access a subject should have for a specific object and then allows or denies types of access based on the rules. This access control model is typically layered on top of another access control model.
  • Illustrative examples for 5.2.C.3:
    • There is a rule that prohibits subjects (even those who would normally have access) from accessing a certain database (the object) outside of local working hours. When a subject attempts to access the database, even if they are authorized to access it, they will be denied access if it is outside the time designated by the rule.
• 5.2.C.4 Discretionary access control (DAC) gives individual subjects the ability to set the type of access that other subjects have on objects they own. In DAC models some subjects are designated as administrators or super users, and they have the ability to override the access controls established by other subjects.
  • Illustrative examples for 5.2.C.4:
    • Bob creates a file (an object) and decides to give Alice permission to edit the file, to give Frank permission to view the file only, and to deny everyone else access to the file altogether.
• 5.2.C.5 Mandatory access control (MAC) follows strict rules for which types of access each subject level has for objects that are above their level, at their level, or below their level. Subject and object levels are assigned by an external administrator.
• 5.2.C.6 The Bell-LaPadula model is a MAC model that is often used by governments and military organizations to control the security of information. This model has the following two important properties:
  • i. The Simple Security Property states that subjects may not read objects that are above their level.
  • ii. The * (Star) Security Property states that subjects may not write to objects below their level.
  • These rules taken together are often summarized as “write up, read down” (WURD).
• 5.2.C.7 The principle of least privilege is the idea that entities should be given exactly as much access as they need to perform their function and no more.

Learning Objective 5.2.D: Configure access control settings on a Linux-based system.

• 5.2.D.1 Authorization is when an entity is granted permission to have a certain type of access to a resource. Access controls are put in place to control which users have what types of access to which data.
• 5.2.D.2 There are three types of access to a file in Linux that can be set, and they always come in the following order:
  • i. Read access allows a user to view the contents of a file.
  • ii. Write access allows a user to make changes to a file.
  • iii. Execute access allows a user to run a binary file such as a program.
  • These are abbreviated rwx, respectively. If a user only has read and execute permissions (not write), then it would display as r-x. The - symbol indicates the absence of that permission.
• 5.2.D.3 There are three default entities for which permissions are set and always in this order: (1) the file owner, (2) the file group, and (3) all other users. The three sets are displayed with no spaces (e.g., rwxrwxrwx).
• 5.2.D.4 To view the current permission settings for a file, use the command ls -l, which will show the current settings for the default entities. If there is a + symbol at the end of the permissions, this means that other permissions have been set for that file and it can be viewed with the getfacl command.
• 5.2.D.5 To modify the permission settings for a file, use the chmod command. This command can be used with the numeric method or the symbolic method.
• 5.2.D.6 To use chmod in the numeric method the syntax is chmod ### filename. Each of the three ### represents one of the three entities mentioned above (the owner, the group, other nongroup users).
  • The first # = the owner
  • The second # = the group
  • The third # = other nongroup users
  • The permission for each entity is determined by adding up the values for the types of access to be granted:
  • 0 = no permissions
  • 1 = execute
  • 2 = write
  • 4 = read
  • Therefore 3 sets permission to write and execute, 5 sets permission to read and execute, 6 sets permission to read and write, and 7 sets permission to read, write, and execute.
  • Illustrative examples for 5.2.D.6:
    • The command chmod 750 test would set the permissions for the owner to read, write, and execute, for the group to read and execute, and for everyone else to no access at all.
    • The command chmod 543 test would set the permissions for the owner to read and execute, for the group to read only, and for everyone else to write and execute.
    • The command chmod 777 test would set the permissions for all three entities to read, write, and execute for the file test.
• 5.2.D.7 To use chmod in the symbolic method the syntax is chmod entity +(or –) permission filename. The entities are the user owner, the group, and other nongroup users. Each entity is represented with a single letter.
  • u = user owner
  • g = group
  • o = others
  • a = all
  • Permission can be either added or removed to any combination of entities.
  • • = add the permission
  • – = remove the permission
  • The permissions that can be set are read, write, and execute.
  • r = read
  • w = write
  • x = execute
  • Entities and permissions can be combined in a single command. To add the read and execute permissions for the group and user owner for a file called testfile, the command would be chmod ug+rx testfile.

Learning Objective 5.3.A: Explain how encryption can be used to protect files.

• 5.3.A.1 The purpose of cryptography is to hide information. A cryptographic algorithm defines a process for encrypting and decrypting information. Encryption is the process of hiding the information, and decryption is the process of reversing the encryption to retrieve the original information.
• 5.3.A.2 An encryption algorithm defines a process for combining the information to be encrypted with a predefined key. The information to be encrypted is called the plaintext. The output of the encryption algorithm is called the ciphertext.
• 5.3.A.3 The number of possible keys that can be used in an encryption algorithm is called the keyspace. The larger the keyspace, the longer it will take an adversary to discover the correct key by random chance.
• 5.3.A.4 Cryptographic algorithms are classified by whether they use one key or two keys.
  • Symmetric encryption algorithms use the same key to encrypt and decrypt information.
  • Asymmetric encryption algorithms use two different keys—one to encrypt information and the other to decrypt information.
• 5.3.A.5 Cryptographic algorithms are also classified by whether they process information one bit at a time or in fixed-size chunks of bits.
  • Block encryption handles information in fixed-size chunks called blocks, producing an output block for each input block.
  • Stream encryption handles input information continuously, producing output one element at a time.

Learning Objective 5.3.B: Apply symmetric encryption algorithms to encrypt and decrypt data.

• 5.3.B.1 Computer-based encryption algorithms operate on binary data. The most common symmetric encryption algorithm is the Advanced Encryption Standard (AES). AES encryption is used to secure Wi-Fi transmissions, internet browsing, file encryption on disks, and hardware-level encryption on processors.
• 5.3.B.2 AES is a symmetric key block cipher that encrypts data in 128-bit blocks (16 bytes). AES can operate with keys of varying lengths. Longer keys produce more secure encryption but require more time to encrypt and decrypt.
• 5.3.B.3 Symmetric encryption and decryption can be performed using the command line, specialized software, or web-based tools.
  • On a command line interface, users can encrypt or decrypt with OpenSSL.
  • Specialized software like AES Crypt is an open source tool that can encrypt and decrypt files.
  • There are many web-based tools for encrypting and decrypting files.
• 5.3.B.4 Using OpenSSL in a CLI, a user can encrypt and decrypt a file using the following commands (note that the encryption key is derived from the password provided):
  • To encrypt a file named test with AES using a 128-bit key, use the command: openssl enc -aes-128-cbc -e -in test -k password -out test.enc
  • To decrypt the encrypted file using the same key, use the command: openssl enc -aes-128-cbc -d -in test.enc -k password -out text

Learning Objective 5.4.A: Determine the appropriate asymmetric key to use when sending or receiving encrypted data.

• 5.4.A.1 Asymmetric encryption allows users to communicate securely without prearranging a shared secret key.
• 5.4.A.2 When using asymmetric encryption, each entity that will be receiving data must first generate a key pair. Key pairs are binary strings of equal length that are generated at the same time through a mathematical process. One key is designated as the public key and the other as the private key. The keys are mathematical inverses of each other— each key reverses its partner. Either key can be used to encrypt information, but only the other key in the key pair will then be able to decrypt it.
• 5.4.A.3 Once the receiver generates the key pair, the private key must be stored securely. If the private key is exposed, shared, stolen, corrupted, or compromised the key pair must be deleted and a new key pair must be generated, because the security of the encryption algorithm rests on the security of the private key. The public key is published for anyone to view and use.
• 5.4.A.4 To send information securely to someone, the sender will use the receiver’s public key to encrypt the data and send it. Only the receiver who has the private key will be able to decrypt and read the information.

Learning Objective 5.4.B: Explain why the length of a key impacts the security of encrypted data.

• 5.4.B.1 Longer keys result in larger keyspaces. For binary keys, an n-bit length key has a keyspace of $2^n$.
• 5.4.B.2 Using an application to randomly guess an n-bit length encryption key means that on average an adversary will be able to guess the correct key in $2^n \div 2$ (or $2^{n-1}$) guesses.
• 5.4.B.3 Although longer keys are more secure, they also require more time to encrypt and decrypt messages.
• 5.4.B.4 Computational processing power and efficiency continue to improve, allowing software to guess keys faster. Key-length recommendations for both symmetric and asymmetric encryption algorithms are periodically increased to account for increased processing power.
• 5.4.B.5 Key-length comparison is only valid when comparing keys for the same cryptographic algorithm.
  • Illustrative examples for 5.4.B.5:
    • An AES 256-bit key is more secure than an AES 128-bit key.
    • An RSA 4096-bit key is more secure than an RSA 2048-bit key.
    • RSA and AES keys cannot be directly compared to one another in determining the level of security.

Learning Objective 5.4.C: Apply asymmetric encryption algorithms to encrypt and decrypt data.

• 5.4.C.1 Common asymmetric encryption algorithms include RSA and elliptic curve cryptography (ECC). Asymmetric algorithms are used in many applications, including digital signatures and digital certificates.
• 5.4.C.2 As with symmetric encryption, asymmetric encryption and decryption can be performed using the command line, specialized software, or web-based tools.
  • On a command line interface, users can encrypt or decrypt with OpenSSL.
  • Specialized software like RSA Encryption Tool is an open source tool that can encrypt and decrypt files.
  • There are many web-based tools for encrypting and decrypting files.
• 5.4.C.3 In a CLI, a user can generate an asymmetric key pair and encrypt or decrypt files as necessary.
  • To generate a 2048-bit RSA key pair and save the key to a file named rsa.pem use the command: openssl genrsa -out rsa.pem 2048
  • To extract the public key from rsa.pem into a file named public.pem, use the command: openssl rsa -pubout -in rsa.pem -outform PEM -out public.pem
  • To encrypt the file test using RSA encryption and the key file public.pem, use the command: openssl pkeyutl -encrypt -pubin -inkey public.pem -in test -out test.enc
  • To decrypt the test.enc file using the rsa.pem file, run the command: openssl pkeyutl -decrypt -inkey rsa.pem -in test.enc -out test

Learning Objective 5.5.A: Identify the application security principles of secure by design and security by default.

• 5.5.A.1 Secure by design is an initiative that encourages companies to include security in all phases of product development including design. When organizations implement secure by design, security is a design principle not just a technical feature.
• 5.5.A.2 Secure by design includes three design principles:
  • i. Companies should take ownership of customer security outcomes. Companies should build products that meet the security needs of their customers.
  • ii. Companies should embrace radical transparency and accountability. Sharing relevant security-related product news and updates quickly increases security for everyone.
  • iii. Companies should build organizational structure and leadership to implement secure by design. Companies need leaders who are focused on security and have a security-first posture.
• 5.5.A.3 Secure by design includes the concept of secure by default, which is the idea that security features for software and devices should be enabled by default. Devices and software should be secure to use out of the box, with security features already enabled.

Learning Objective 5.5.B: Explain how user input sanitization protects applications.

• 5.5.B.1 When users enter input into an application, the application typically encases that input in special characters to process it. The characters that encase the user input are called control characters and include the single quote, the double quote, and the semicolon.
• 5.5.B.2 When creating a program that takes user input, programmers should use a function to verify that user input meets their expected criteria and does not include any control characters that could be used to manipulate the system. This verification function can sanitize user input by removing potentially malicious characters, or it can give the user an error and force the user to provide different input. This can protect against many application attacks, including:
  • SQL injection attacks
  • XSS attacks
  • Directory traversal attacks

Learning Objective 5.6.A: Explain how to detect attacks on data.

• 5.6.A.1 Devices track and log when data are accessed and by whom. The process of recording and monitoring user activities is called accounting. Analysis of these logs can reveal malicious activity when an adversary attempts to access, copy, move, or delete data. Suspicious activity can include:
  • Accessing files that aren’t typically accessed
  • Accessing files or applications outside of a user’s normal patterns (including time of day, location, and device type)
  • Attempts to delete or copy sensitive files
• 5.6.A.2 A honeypot is a file that appears as if it contains valuable data (e.g., credit card information, PII, passwords), but the data in the file are fake. A system can alert defenders if someone attempts to access the honeypot. Since the honeypot is a fake file, there is no legitimate reason to be accessing it, and any attempted access would be an indicator of malicious activity.
• 5.6.A.3 Cryptographic hash functions can generate a digest for data and can reveal if data have been altered. If a file has changed unexpectedly, this can be a sign of malicious activity.

Learning Objective 5.6.B: Determine controls for detecting attacks against applications or data.

• 5.6.B.1 Cost is a criterion in determining detective controls. Detective controls like honeypots and using hash values to check data integrity are inexpensive. Some organizations invest in third-party data loss prevention (DLP) services, which monitor data access, usage, and transmission by users throughout the organization to detect suspicious activity; DLP services provide strong detection capabilities at a higher cost.
• 5.6.B.2 Sensitivity or criticality of data or applications is a criterion in determining detective controls. More sensitive or critical data or applications are more likely targets of an adversary and should be monitored more closely.
• 5.6.B.3 Classification of data is a criterion in determining detective controls. Data that have been classified as private, educational, healthcare, or financial often have legal or regulatory detection and monitoring requirements.

Learning Objective 5.6.C: Evaluate the impact of a method for detecting attacks against an application or data.

• 5.6.C.1 To operate at an effective speed, log analysis needs to be augmented with some automation. Honeypots offer near instantaneous detection capabilities.
• 5.6.C.2 Some DLP tools, honeypots, and realtime automated log analysis provide alerts as an attack is happening. These tools allow for a prompt response that can stop an attack before it does more harm. Retrospective log analysis and the use of cryptographic hashes to verify data integrity identify attacks after they have occurred.
• 5.6.C.3 False negatives can occur in applications and data attack detection. Cryptographic hash functions only detect if data have been altered. An adversary could view and steal data without altering it, and a cryptographic hash function would not detect this. Honeypots cannot detect adversaries that do not attempt to access them.

Learning Objective 5.6.D: Identify whether a file has been altered by verifying its hash.

• 5.6.D.1 Cryptographic hash functions can help identify changes in a file because they are repeatable: the same input always produces the same output for a given hash function.
• 5.6.D.2 Hashes can be calculated using the command line on a computer, a website, or specialized software.
  • In Windows Powershell, if a user wanted to generate the SHA256 hash for a file named testfile, they would use the command: Get-FileHash testfile -Algorithm SHA256
  • In BASH the same could be accomplished with the command: sha256sum testfile
  • In zsh, the common command line terminal on Apple computers, this could be accomplished with the command: shasum -a 256 testfile
• 5.6.D.3 A file can be hashed and its hash output recorded. Then it can be hashed again later, and the second hash output can be compared to the previous hash output for the same file. If a file’s hash changes, then the file was altered between when the first and second hashes were generated.

Learning Objective 5.6.E: Apply detection techniques to identify and report indicators of application attacks by analyzing log files.

• 5.6.E.1 SQL injection attacks can be detected by reviewing application and server logs of user input for SQL control words and symbols such as:
  • A single (') or double (") quote character
  • Boolean conditions like OR 1=1
  • A double dash (which indicates a comment in SQL): --
  • SQL control words (always in capital letters) like WHERE, IN, FROM
• 5.6.E.2 XSS attacks can be detected by reviewing user input for suspicious tags, particularly the tag.
• 5.6.E.3 For web applications, buffer overflows can be detected by checking the amount of data the user is sending to the web application in their request. The fields commonly checked are the URL length, cookie length, query string length, and total request length. Long strings in any of these fields can be an indicator of an attempted buffer overflow attack.
• 5.6.E.4 Directory traversal attacks can be detected by reviewing application and server logs. HTTP GET requests that include paths with sequences of ../ are indicators of an adversary attempting a directory traversal.