Day 24: Post-Exploitation Mastery — What Happens After Root? 🕵️‍♂️

#cybersecurity #linux #security #tutorial

🛠️ The Post-Exploitation Checklist

In a real-world engagement, getting a root shell is temporary. The system might reboot, or the admin might kill your process. You need Persistence.

1. Maintaining Access (Persistence)

The SSH Backdoor: Adding an attacker's public key to /root/.ssh/authorized_keys allows for passwordless, permanent remote access.
The Cron Persistence: Scheduling a hidden task to send a reverse shell every minute ensures that even if you lose your connection, the system "calls" you back automatically.

2. Credential Harvesting & Shadow Cracking

Once you have root, you own the identity store.

The Shadow File: Accessing /etc/shadow allows an attacker to dump password hashes for offline cracking using tools like John the Ripper or Hashcat.
The History Leak: Always check ~/.bash_history. Users often accidentally type passwords directly into the command line (e.g., mysql -u root -p'password123').

3. Lateral Movement (Pivoting)

Root on one machine is often the key to the next.

SSH Key Hunting: Searching for id_rsa files. These private keys are often used to automate logins between servers. If you find a key on the web server, it might grant you access to the database or backup server without a single exploit.
Credential Reuse: Using harvested passwords to try and log into other machines on the same network.

🕵️‍♂️ Advanced Concept: Process Hijacking

I analyzed a scenario where a root-owned service runs a script in a world-writable directory (e.g., /opt/app.py with 777 permissions).

The Attack: Overwrite the script with a payload.
The Result: The system continues to execute your malicious code with root privileges in a continuous loop. It’s stealthy and highly effective.

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