| name | analyzing-persistence-mechanisms-in-linux |
| description | Detect and analyze Linux persistence mechanisms including crontab entries, systemd service units, LD_PRELOAD hijacking, bashrc modifications, and authorized_keys backdoors using auditd and file integrity monitoring |
| domain | cybersecurity |
| subdomain | threat-hunting |
| tags | ["linux-persistence","crontab","systemd","ld-preload","auditd","threat-hunting","incident-response"] |
| mitre_attack | ["T1053.003","T1543.002","T1574.006","T1546.004","T1098.004"] |
| version | 1.0 |
| author | mahipal |
| license | Apache-2.0 |
| d3fend_techniques | ["Executable Denylisting","Execution Isolation","File Metadata Consistency Validation","Process Termination","Content Format Conversion"] |
| nist_csf | ["DE.CM-01","DE.AE-02","DE.AE-07","ID.RA-05"] |
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
- Scan Crontab Entries — Enumerate all user crontabs, /etc/cron.d/, /etc/cron.daily/, and anacron jobs for suspicious commands
- Audit Systemd Units — Check /etc/systemd/system/ and ~/.config/systemd/user/ for non-package-managed service and timer units
- Detect LD_PRELOAD Hijacking — Check /etc/ld.so.preload and LD_PRELOAD environment variable for injected shared libraries
- Inspect Shell Profiles — Scan .bashrc, .bash_profile, .profile, /etc/profile.d/ for injected commands or reverse shells
- Check SSH Authorized Keys — Audit all authorized_keys files for unauthorized public keys with command restrictions
- Correlate Auditd Logs — Search auditd logs for file modification events on persistence paths to build an installation timeline
- Generate Persistence Report — Produce a risk-scored report of all discovered persistence mechanisms
Expected Output
- JSON report of all persistence mechanisms found with risk scores
- Timeline of persistence installation from auditd correlation
- MITRE ATT&CK technique mapping (T1053, T1543, T1574, T1546)
- Remediation commands for each detected persistence mechanism
