Heuristic, signature, and reputation-based methods are classic static analysis approaches (D) because they evaluate artifacts and indicators without requiring full execution observation of the payload's runtime behavior. In Proofpoint email security, these methods appear across attachment and URL analysis pipelines:
signature-based matching for known malware patterns, heuristic rules for suspicious structures (macro patterns, obfuscation traits, spoofing characteristics), and reputation scoring for URLs/domains/IPs based on historical maliciousness and observed telemetry. This differs from behavioral/dynamic analysis, which relies on execution in a sandbox environment to observe actions (process injection, network callbacks, file writes).
In day-to-day IR triage, static techniques are often the first layer of detection because they are fast and scalable, enabling immediate condemnation and quarantine decisions at the gateway. Analysts then use TAP dashboards to corroborate static verdicts with additional context (campaign patterns, click behavior, impacted users) and decide containment actions (TRAP pulls, blocklists, user remediation). Understanding that these are static techniques helps responders interpret verdict confidence and know when additional dynamic evidence is needed.