Stealth rootkit targeting F5 BIG-IP could expose enterprise identity gateways
Sophos analyzed a stealth Linux rootkit that hides a web shell in memory on compromised F5 BIG-IP APM identity gateways, evading file-based detection.
Sophos analyzed a second-stage Linux rootkit implant found in compromised F5 BIG-IP APM environments running Apache and PHP, linked to exploitation of CVE-2025-53521, an unauthenticated RCE. The implant hooks Apache's PHP-loading process and serves modified in-memory versions of three legitimate webtop PHP files (apm_css.php3, full_wt.php3, webtop_popup_css.php3), leaving on-disk files untouched so hashes and integrity checks pass. It also establishes access via an authenticated local UNIX socket that can provide an interactive /bin/bash session. Experts warn compromised APM appliances, which handle federated SSO and terminate TLS at enterprise perimeters, could enable SSO token theft and lateral movement to trusted downstream applications.
New Mirai variant adds stealth capabilities to notorious botnet code
FortiGuard Labs reports new Mirai-derived botnet Evooo1Bot actively exploits unpatched routers and edge devices, adding encrypted C2, stealthy SSH scanning, and proxying.
FortiGuard Labs has identified Evooo1Bot, a previously undocumented Linux malware based on the Mirai botnet code, which has been actively exploiting unpatched vulnerabilities in internet-facing hardware for at least a month. Targeted devices include routers and edge hardware from Alcatel, D-Link, Mitsubishi Electric, Netgear, Tenda and Telesquare, with telemetry showing activity in North and South America, Europe, India, China and Japan. Beyond Mirai's usual DDoS functions, the variant adds encrypted C2 communications, a honeypot-aware SSH scanner, a sniffer for unchanged default credentials, and abuse of the SOCKS protocol to turn compromised devices into persistent proxies for concealing origin and pivoting into internal networks.