A security analyst notices an alert from the 'MITRE ATT&CK - Initial Access' tactic. Which data source should be primary for investigating this alert?
Initial Access covers techniques such as phishing and drive-by compromise, which arrive via email attachments, links, or malicious web content. Email security and web proxy logs record those delivery vectors, giving the primary evidence needed to trace how the intrusion began.
Why this answer
MITRE ATT&CK's Initial Access tactic covers techniques like phishing (T1566), exploitation of public-facing applications (T1190), and valid accounts (T1078). Phishing is the most common initial access vector, so email security logs are primary for detecting malicious attachments, links, and sender anomalies. Web proxy logs are also primary because they capture drive-by compromise and access to malicious URLs used in initial access.
Together they provide the telemetry needed to investigate Initial Access alerts.
Exam trap
SPLK-5001 often tests whether candidates confuse Initial Access with Execution or Credential Access — the trap is selecting process or authentication logs when the question is specifically about how the attacker first got in.
How to eliminate wrong answers
Option B is wrong because local authentication logs map to Credential Access (e.g., brute force, T1110) or Lateral Movement, not Initial Access — they show logon attempts on a host, which is a later-stage concern. Option C is wrong because process audit logs correspond to Execution (T1059) and later tactics; process creation happens after initial access is achieved. Option D is wrong because registry modification logs map to Persistence (T1547) and Defense Evasion (T1112), which occur after the attacker has already gained a foothold.