C2 Data Hidden in Image via Steganography

Darshan Thummar@Mighty

•updated Jun 12, 2026•0•0•8

This rule detects potential command and control (C2) communication where data is hidden within image files using steganography. It specifically looks for HTTP responses (flow:to_client) containing JPEG image headers ('FF D8 FF') within the first 3 bytes, with a file size greater than 500,000 bytes. A threshold is applied to trigger an alert if 5 such events occur from the same destination within 60 seconds, indicating a potential high volume of large steganographic image transfers.