Malicious Koske Userland Rootkit Installation via ld.so.preload (via file_event)

ATT&CK techniques

Execution → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
- T1574.006Dynamic Linker Hijacking
Persistence
- T1574.006Dynamic Linker Hijacking
Priv Esc
- T1574.006Dynamic Linker Hijacking
Defense Evasion
- T1014Rootkit
- T1574.006Dynamic Linker Hijacking
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects installation of the Koske userland rootkit that hooks readdir through LD_PRELOAD to hide files and processes. It fires when the hideproc.so shared object is written to disk or when /etc/ld.so.preload is modified to load it globally. Modification of ld.so.preload is uncommon on most systems and is a strong rootkit indicator.

Reporting behind it

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Suspicious LD_PRELOAD Library Injection via PUMAKIT Userland Rootkit

Malicious VoidLink Pinned eBPF Map in BPF Filesystem (via file_event)

Malicious Koske Userland Rootkit Installation via ld.so.preload (via file_event)

Pivot detection · T1014 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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