feat: add NIST CSF 2.0 nist_csf field to all 754 cybersecurity skills

Mapped every skill to NIST CSF 2.0 subcategory IDs (GV/ID/PR/DE/RS/RC functions)
based on subdomain and content analysis. Restores 11 skills corrupted during
prior rebase, re-enriching with ATLAS, D3FEND, NIST AI RMF, and CSF 2.0 fields.

All 754 skills now carry structured mappings for all 5 security frameworks:
- MITRE ATT&CK (in tags)
- MITRE ATLAS v5.5 (atlas_techniques)
- MITRE D3FEND v1.3 (d3fend_techniques)
- NIST AI RMF 1.0 (nist_ai_rmf)
- NIST CSF 2.0 (nist_csf)

skills/analyzing-persistence-mechanisms-in-linux/SKILL.md

@@ -1,6 +1,10 @@
 ---
-{}
----tags:
+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
@@ -8,4 +12,61 @@
 - auditd
 - threat-hunting
 - incident-response
+mitre_attack:
+- T1053.003
+- T1543.002
+- T1574.006
+- T1546.004
 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
+
+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. **Inspect Shell Profiles** — Scan .bashrc, .bash_profile, .profile, /etc/profile.d/ for injected commands or reverse shells
+5. **Check SSH Authorized Keys** — Audit all authorized_keys files for unauthorized public keys with command restrictions
+6. **Correlate Auditd Logs** — Search auditd logs for file modification events on persistence paths to build an installation timeline
+7. **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