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Dissecting a PHP web server rootkit

September 7, 2026 · Sophos Threat Research · Severity: HIGH

Sophos researchers dissect a PHP web server rootkit that modifies legitimate PHP files on compromised servers. The rootkit maintains persistence by hooking into PHP execution flow and can evade detection by common security tools.

Key Takeaways

  • Sophos X-Ops published a deep-dive analysis of an insidious PHP webshell rootkit designed for long-term server persistence.
  • PHP webserver administrators should audit file integrity, restrict upload permissions, and monitor for anomalous PHP file modifications.
  • Webshell rootkits can evade traditional detection; runtime monitoring and behavior analysis are critical for identifying compromised servers.
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