Forensic Investigation of a Compromised VPS: A Step-by-Step Guide 
In the digital realm, cyber threats lurk around every corner. Discovering that your VPS server has been compromised can be a daunting experience. But, equipped with the right tools and knowledge, you can rise to the challenge. Here’s a detailed guide to conducting a forensic investigation on a compromised Ubuntu VPS server. 
1. Network Quarantine 
Before diving deep, ensure the compromised system’s communication is restricted. This prevents further damage and stops potential data exfiltration.
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For Remote Access: Restrict the server to communicate only with your IP, blocking all other traffic.
sudo ufw default deny incoming sudo ufw default deny outgoing sudo ufw allow from YOUR_IP_ADDRESS to any port 22 sudo ufw enable -
For Physical Access: If you’re on-site, you can safely disconnect the server from the network.
2. Capture the Ghosts in the Machine 
Memory can reveal secrets that vanish upon reboot. Secure them!
sudo insmod lime-<version>.ko "path=/path/to/output.lime format=lime"
3. Mirror, Mirror on the Wall 
Preserve the disk’s original state by creating an exact copy. This ensures the evidence remains pristine.
sudo dd if=/dev/sda of=/path/to/output.img bs=4M status=progress
4. The Log Chronicles 
Logs can narrate the hacker’s tale. Dive into them to uncover unauthorized activities.
sudo cat /var/log/auth.log
sudo cat /var/log/syslog
5. Unraveling the User’s Tale 
What did the intruder do? The command history might spill the beans.
sudo cat /home/*/.bash_history
6. Modified Files: The Silent Witnesses 
Identify files that the hacker tampered with or introduced.
sudo find / -type f -mtime -7
7. Spotting the Rogue Process
Keep an eye out for unfamiliar processes. They might be the hacker’s minions.
top
8. Network Reconnaissance 
Identify suspicious external connections. Who was the hacker communicating with?
sudo netstat -tuln
9. The Malware Hunt 
Scan and cleanse the system of any lurking threats.
sudo freshclam
sudo clamscan -r --bell -i /
sudo rkhunter --update
sudo rkhunter --check
10. Dive Deeper with Data Analysis 
Use specialized tools like Volatility and Autopsy to uncover hidden secrets.
11. The Documentation Saga 
Every detail matters. Document your findings meticulously for future reference.
12. Rise from the Ashes: Remediation 
Secure and fortify your system, ensuring it’s ready to face future threats.
13. The Grand Finale: Reporting 
Compile your findings and present them. Knowledge is power, and sharing it ensures everyone is better prepared.
In the vast expanse of the cyber world, being vigilant and informed is the key. Arm yourself with the right tools and knowledge, and you’ll be well-equipped to tackle any cyber challenge that comes your way! 
Stay vigilant and keep those servers fortified! 
