Day 10: Advanced Privilege Escalation & Security Audits 🕵️‍♂️

Source: Dev.to

Audit Overview

Day 10 of my #1HourADayJourney focused on breaking things to understand how they’re built. To secure a system, you have to think like an attacker. Below are the key findings from the audit.

SUID (Set User ID) Vulnerability

• What it does: Allows a program to run with the privileges of the file owner.
• The vulnerability: If a binary is owned by root and has the s bit set, it runs as root. If the binary is a shell, you obtain a root shell.
• Lesson: Always check for binaries with the s permission during system audits.

Dangerous Script Pattern

• Scenario: A script owned by root is executable by a group you belong to, or writable by you.
• Exploit: You can inject a payload into the script, wait for the cron daemon to trigger it as root, and spawn a privileged shell (/bin/bash -p).
• Example: If a cron job calls backup.sh instead of /usr/local/bin/backup.sh, the system searches the $PATH. Controlling a directory earlier in the path lets you place your own backup.sh there.

Best Practices

• Use absolute paths in cron jobs and configuration files to avoid path hijacking.
• Treat security as a chain: A single weak link—such as a writable script in a cron job—can compromise the entire system.

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