analyzing-persistence-mechanisms-in-linux

# Analyzing Persistence Mechanisms in Linux ## Overview Adversaries establish persistence on Linux systems through crontab jobs, systemd service/timer units, LD_PRELOAD library injection, shell profile modifications (.bashrc, .profile), SSH authorized_keys backdoors, and init script manipulation. This skill scans for all known persistence vectors, checks file timestamps and integrity, and correlates findings with auditd logs to build a timeline of persistence installation. ## When to Use - When investigating security incidents that require analyzing persistence mechanisms in linux - When building detection rules or threat hunting queries for this domain - When SOC analysts need structured procedures for this analysis type - When validating security monitoring coverage for related attack techniques ## Prerequisites - Root or sudo access on target Linux system (or forensic image) - auditd configured with file watch rules on persistence paths - Python 3.8+ with standard library (os, subprocess, json) - Optional: OSSEC/Wazuh agent for file integrity monitoring alerts ## Steps 1. **Scan Crontab Entries** — Enumerate all user crontabs, /etc/cron.d/, /etc/cron.daily/, and anacron jobs for suspicious commands 2. **Audit Systemd Units** — Check /etc/systemd/system/ and ~/.config/systemd/user/ for non-package-managed service and timer units 3. **Detect LD_PRELOAD Hijacking** — Check /etc/ld.so.preload and LD_PRELOAD environment variable for injected shared libraries 4. **Inspe...