DCNSA Level II
Network Security cheat sheet
Every chapter's key points, formulas and definitions on one page, for the last week before the exam. Each heading links to the chapter that explains it.
Foundations of network security
- Security protects systems, networks and data from unauthorised access, damage or disruption, through technical controls, policy and trained behaviour together.
- A vulnerability is a weakness a threat could exploit; it becomes an attack only when someone deliberately tries to exploit it.
- A well-defended network layers several controls, such as access control, antivirus, firewalls, behavioural analytics, data loss prevention, web security and network segmentation, rather than relying on any single one.
- Malware attacks a system through malicious software, while social engineering manipulates people, which is why no firewall or antivirus stops a user who hands over their own password.
- A breach can expose sensitive data, disrupt operations and damage reputation, and in Kenya the Data Protection Act, 2019 and the Computer Misuse and Cybercrimes Act, 2018 turn weak security into a legal exposure as well.
Key terms
- Security
- Protecting systems, networks and data from unauthorised access, damage or disruption, through a combination of technical controls, policy and trained behaviour.
- Vulnerability
- A weakness in a system, in its software, configuration, or the people operating it, that a threat could exploit if left unaddressed.
- Attack
- A deliberate attempt to exploit a vulnerability and compromise a system, distinguishing a genuine incident from a vulnerability that exists but has not (yet) been exploited.
- Access control
- Restricting who and what can connect to or use network resources, the first gate any user or device must pass.
- Antivirus
- Software detecting and removing malicious code before, or after, it runs on a system.
- Application security
- Hardening the applications running on the network against exploitation: secure coding practice, patching, and configuration that closes off unnecessary features an attacker could abuse.
- Behavioural analytics
- Detecting anomalies by learning what normal network activity looks like for a given user or system, and flagging deviations that a signature-based tool would miss entirely, since the deviation itself, not a known malicious pattern, is what is detected.
- Data loss prevention (DLP)
- Controls that detect and block sensitive data from leaving the network improperly, such as a large customer database being copied to an external drive or emailed outside the organisation.
- Firewall
- Monitors and controls traffic entering and leaving the network based on defined rules, the network's first line of defence at its boundary.
- Web security
- Controls protecting users and systems from web-based threats: malicious sites, drive-by downloads, and content filtering against known-bad destinations.
- Network segmentation
- Dividing a network into smaller isolated zones, so a breach in one segment does not automatically expose the whole network, developed fully in the chapter on deploying security solutions.
- Malware
- Malicious software, viruses, worms, ransomware and spyware, designed to damage, disrupt or steal from a system, and the target antivirus and behavioural analytics exist to catch.
- Social engineering attacks
- Manipulating people, rather than exploiting a technical flaw, into revealing credentials or granting access: phishing, pretexting and impersonation, developed fully in the chapter on testing network vulnerability. No firewall or antivirus stops a user who is convinced to hand over their own password voluntarily.
The rest of the sheet covers
- Establish a network security framework
- Deploy network security solutions
- Test network vulnerability
- Exam technique and revision
- Glossary