How I Use AuditD to Catch Silent Security Threats on Linux | by Faruk Ahmed | May, 2025

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How I Use AuditD to Catch Silent Security Threats on Linux

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Intro:

Some attacks don’t show up in your logs. They don’t crash services or trigger alerts. They quietly change permissions, edit files, or execute binaries you weren’t expecting. That’s where AuditD comes in — the Linux auditing daemon that tells you exactly what happened, when, and by whom. Here’s how I set it up and use it to monitor the parts of my system that attackers love to touch.

1. Installing AuditD

✅ Ubuntu:

sudo apt install auditd

✅ Red Hat:

sudo yum install audit

Then enable and start it:

sudo systemctl enable auditdsudo systemctl start auditd

2. Monitor Access to /etc/passwd and /etc/shadow

These files are often targeted for privilege escalation or user creation.

auditctl -w /etc/passwd -p wa -k passwd_watchauditctl -w /etc/shadow -p wa -k shadow_watch

✅ Check activity:

ausearch -k passwd_watch

3. Watch for Unexpected Binary Executions

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Free Linux Security Audit Tool

If you're checking a Linux server for suspicious activity, it's also worth reviewing SSH settings, user access, listening services, and firewall configuration.

I built a free Linux Security Audit Tool to make some of those checks easier. It runs locally and generates reports you can review afterward.

NextGenAlert Linux Security Audit — Free Community Edition

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