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Mahipal
2fb6a9faff
Each rewritten description now states both what the skill does (concrete capability, named tools/artifacts) and an explicit when-to-use trigger, improving agent discovery/activation. Grounded in each skill's own body; changes confined to the `description` field only (bodies and all other frontmatter untouched). Produced by a gated audit->rewrite->recheck loop (548 -> 0 flagged) with a sampled anti-invention check (0 ungrounded). Schema: 817/817 pass. Framework-ID gate: 0 defects.
73 lines
3.1 KiB
Markdown
73 lines
3.1 KiB
Markdown
---
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name: analyzing-persistence-mechanisms-in-linux
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description: Scan Linux systems for persistence mechanisms including crontab/systemd entries, LD_PRELOAD injection, shell profile modifications (.bashrc, .profile), and SSH authorized_keys backdoors, then correlate findings with auditd logs into an installation timeline. Use during incident response or threat hunting to detect or confirm how an adversary maintained access to a compromised Linux host.
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domain: cybersecurity
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subdomain: threat-hunting
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tags:
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- linux-persistence
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- crontab
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- systemd
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- ld-preload
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- auditd
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- threat-hunting
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- incident-response
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mitre_attack:
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- T1053.003
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- T1543.002
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- T1574.006
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- T1546.004
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- T1098.004
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version: '1.0'
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author: mahipal
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license: Apache-2.0
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d3fend_techniques:
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- Executable Denylisting
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- Execution Isolation
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- File Metadata Consistency Validation
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- Process Termination
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- Content Format Conversion
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nist_csf:
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- DE.CM-01
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- DE.AE-02
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- DE.AE-07
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- ID.RA-05
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---
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# Analyzing Persistence Mechanisms in Linux
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## Overview
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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.
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## When to Use
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- When investigating security incidents that require analyzing persistence mechanisms in linux
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- When building detection rules or threat hunting queries for this domain
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- When SOC analysts need structured procedures for this analysis type
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- When validating security monitoring coverage for related attack techniques
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## Prerequisites
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- Root or sudo access on target Linux system (or forensic image)
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- auditd configured with file watch rules on persistence paths
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- Python 3.8+ with standard library (os, subprocess, json)
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- Optional: OSSEC/Wazuh agent for file integrity monitoring alerts
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## Steps
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1. **Scan Crontab Entries** — Enumerate all user crontabs, /etc/cron.d/, /etc/cron.daily/, and anacron jobs for suspicious commands
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2. **Audit Systemd Units** — Check /etc/systemd/system/ and ~/.config/systemd/user/ for non-package-managed service and timer units
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3. **Detect LD_PRELOAD Hijacking** — Check /etc/ld.so.preload and LD_PRELOAD environment variable for injected shared libraries
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4. **Inspect Shell Profiles** — Scan .bashrc, .bash_profile, .profile, /etc/profile.d/ for injected commands or reverse shells
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5. **Check SSH Authorized Keys** — Audit all authorized_keys files for unauthorized public keys with command restrictions
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6. **Correlate Auditd Logs** — Search auditd logs for file modification events on persistence paths to build an installation timeline
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7. **Generate Persistence Report** — Produce a risk-scored report of all discovered persistence mechanisms
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## Expected Output
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- JSON report of all persistence mechanisms found with risk scores
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- Timeline of persistence installation from auditd correlation
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- MITRE ATT&CK technique mapping (T1053, T1543, T1574, T1546)
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- Remediation commands for each detected persistence mechanism
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