Ivanti Connect Secure RESURGE Activity Detection

This rule set detects indicators of compromise associated with the RESURGE activity targeting Ivanti Connect Secure devices, as described by CISA. It looks for specific file hashes, the presence of a covert socket path (.logsrv), and modifications to key Ivanti filesystem artifacts such as LD_PRELOAD, DSUpgrade.pm, coreboot.img, and scanner.py. A match indicates potential compromise and requires further investigation to confirm the asset role, timing of file appearance, and comparison with approved maintenance windows. If hits are found, collect logs and file copies, reduce external exposure, and look for unusual activity like unexpected administrator actions or unfamiliar outbound connections.