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What a week. After days of forensic work, exhausting every bit of my feeble brains knowledge and every internal resource, I hit a wall. It was time to call in a collaborator. Yes! I caved to Gemini. I wanted to share this security incident, not as a point of failure, but as a critical learning moment for the community. 

The Surprise Attack
Our security model was focused on common threats, but the attack vector that succeeded was an obscure vulnerability in an older, custom PHP script which I won't mention  (used for image metadata).

October 26th: An attacker exploited a flaw in this script to gain initial shell access as the low privilege apache user.

October 31st: The attacker used that persistent shell to execute a privilege escalation exploit, gaining root access to the entire server. This led to the malicious modification of core configuration files (/tmp/http
d.conf and crontab).

The Role of AI in Forensics
We had the "what" (modified files), but we needed the "how" (the specific entry point). Working with Gemini, became a force multiplier in the investigation

Gemini quickly identified unusual and repeated requests to the obscure php file across different log days, flagging it as the likely entry point.

It identified the critical missing piece in our image upload scripts: a failure to properly validate the file's true content type (magic bytes) and instead relying on the easily faked file extension.

We scanned all web roots for disguised scripts (files named .jpg but containing PHP code), eliminating potential hidden backdoors.


To prevent a recurrence, we took the following steps:

Retired/Patched All Vulnerable Code: The php file and other related upload scripts are now either retired or secured with an exit; command at the top line for immediate mitigation.

Implemented robust a more robust file checks using finfo and getimagesize() to verify the true content of an uploaded file, not just its extension.

Confirmed strict directory permissions (e.g., chmod 755 for folders, 644 for files) and ensured the apache user has no write access to critical configuration directories.

Assume every file upload is hostile. Don't just check the extension; inspect the bytes. After exhausting my feeble brain to the point of no return, I decided to enlist the help of Gemini AI where it helped me take a
chaotic incident and turn it into into a clear roadmap for security improvement.