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Cisco SA - Automated Web Reconnaissance via HTTP Access Errors

This analytic detects probable automated web reconnaissance using Cisco Secure Access proxy telemetry. A high volume of HTTP client errors (401/403/404/etc) across many unique URLs in a short window is consistent…

Description

This analytic detects probable automated web reconnaissance using Cisco Secure Access proxy telemetry. A high volume of HTTP client errors (401/403/404/etc) across many unique URLs in a short window is consistent with directory/file enumeration behavior generated by tools such as Gobuster, DirBuster, ffuf, or Burp Intruder. Detecting this pattern helps identify pre-exploitation scanning activity, insider reconnaissance, compromised endpoints performing discovery, and attempts to find hidden administrative paths, APIs, backups, and exposed application files.

Detection logic

Detection requirements

Platform
PRE

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source category
cisco_secure_access_proxy

Known benign triggers

  • Aggressive web vulnerability scanners, QA automation, uptime monitoring, and authorized security assessments can generate high HTTP error volumes with large URL diversity. Tune by allow-listing known scanner hosts, user agents, test domains, and approved assessment windows using the filter macro.

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