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Hackers deploy Linux rootkit on F5 BIG-IP APM devices, hiding web shell in memory
Sophos analyzed a Linux rootkit, tracked as PoisonedRefresh, on hacked F5 BIG-IP APM devices hiding an in-memory web shell linked to exploited CVE-2025-53521.
Sophos and ESET analyzed an implant (named PoisonedRefresh by ESET) deployed on compromised F5 BIG-IP APM appliances, which serves enterprise, financial, government, and public sector deployments. The second-stage payload intercepts __libc_start_main, hooks Apache's APR module loader (apr_dso_load), RC4-encodes key strings, and rewrites PHP file reads in memory to embed a web shell inside legitimate scripts like apm_css.php3, full_wt.php3, and webtop_popup_css.php3, leaving on-disk files unchanged. A related installer component infects /usr/sbin/httpd, persists across BIG-IP upgrade images, modifies SELinux configuration, and deploys the payload. The malware also creates a Unix domain socket at /run/bigtlog.pipe that hands authenticated local connections to /bin/bash; F5 links the activity to CVE-2025-53521, an unauthenticated RCE in BIG-IP APM already exploited in the wild.
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Rust Supply Chain Attack Puts Build-Time Malware in Crates with 245 Million Downloads
Compromised maintainer account published malicious versions of popular Rust crates with 245M downloads, delivering a build-time payload via typosquatted proc-macro1 dependency.
The Rust Project deleted malicious releases of arrayref 0.3.10, internment 0.8.7, and append-only-vec 0.1.9 from crates.io after a compromised maintainer account added a typosquatted dependency, proc-macro1, whose build script downloaded and executed a remote payload during compilation. Each malicious version was online for 86 to 107 minutes on August 20, 2026, before deletion. The build script disabled TLS validation and deployed OS-specific implants on Unix, macOS, and Windows, with builds alone sufficient to trigger execution. Wiz Research confirmed active exploitation, noting the impacted packages appear in 35% of cloud and code environments and over 75% of Rust-using environments; arrayref alone has 245 million all-time downloads and 403 dependent crates.
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