Basic Concept: LLM firewalls inspect prompts and responses to identify malicious content, policy violations, and attack attempts. To detect known attack patterns, these systems apply inspection techniques that compare content against established threat indicators. CompTIA SecAI+ Study Guide covers LLM security monitoring and detection techniques.

Why A is Correct: Signature matching compares incoming prompts and outgoing responses against a library of known attack signatures, including common prompt injection patterns, jailbreaking attempts, data exfiltration queries, and known malicious payload strings. When content matches a known attack signature, the LLM firewall can block or flag it. Signature matching is an efficient, proven detection technique for identifying known attack patterns traversing an LLM firewall.

Why B is Wrong: Distributed denial-of-service is itself a type of attack, not a detection technique. DDoS floods systems with traffic to cause service unavailability and has no role in detecting attacks through an LLM firewall.

Why C is Wrong: Translation analysis involves converting content between languages or formats. While it might be used to detect obfuscated attacks in different encodings, it is not a standard detection technique for identifying attacks crossing an LLM firewall.

Why D is Wrong: Vulnerability enumeration systematically identifies and catalogs vulnerabilities in systems or applications during security assessments. It is an assessment activity used to discover weaknesses, not a real-time detection technique for attacks traversing an LLM firewall.