BleepingComputer.com: What can you do if your system is compromised?

Hi all,

I'm currently working on riding my desktop computer and laptop of all their evils and I became curious about something. Let's say that your computer/computer network has been hacked by someone. What are they capable of doing once you've disconnected yourself from the network? Would that person/people be able to remotely access my computer and files still? What would happen if I reconnected to the internet again? Would I be safe if I were to connect to a different network than the network you were originally on when your machine was compromised? If one compromised machine is reconnected to a network that a "clean" computer is on, does that mean that system is compromised/people have access to it as well?

I've already taken a look at the tutorial on How can you figure out if you've been hacked? and I think for the time-being it's beyond my capabilities/knowledge to pull it off (otherwise I would not be posting, of course). Sorry if you feel this post is misplaced - I wasn't sure if I should group it with malware issues or in the networking forum.

Thanks for any responses!

S.

This allows hackers to remotely control your computer, steal critical system information and download and execute files.

I would counsel you to disconnect this PC from the Internet immediately. If you do any banking or other financial transactions on the PC or if it should contain any other sensitive information, please get to a known clean computer and change all passwords where applicable, and it would be wise to contact those same financial institutions to apprise them of your situation.

Though the trojan has been identified and can be killed, because of it's backdoor functionality, your PC is very likely compromised and there is no way to be sure your computer can ever again be trusted. Many experts in the security community believe that once infected with this type of trojan, the best course of action would be a reformat and reinstall of the OS. Please read these for more information:

How Do I Handle Possible Identify Theft, Internet Fraud and CC Fraud?
When Should I Format, How Should I Reinstall

We can still clean this machine but I can't guarantee that it will be 100% secure afterwards. Let me know what you decide to do.


Reformatting

Your decision as to what action to take should be made by reading and asking yourself the questions presented in the "When should I re-format?" and What Do I Do? links I previously provided. As I already said, in some instances an infection may have caused so much damage to your system that it cannot be completely cleaned or repaired. Wiping your drive, reformatting, and performing a clean install of the OS or doing a factory restore removes everything and is the safest action but I cannot make that decision for you.

Reformatting a hard disk deletes all data. If you decide to reformat, you can back up all your important documents, data files and photos. The safest practice is not to backup any autorun.ini or .exe files because they may be infected. Some types of malware may disguise itself by adding and hiding its extension to the existing extension of files so be sure you take a close look at the full name. After reformatting, as a precaution, make sure you scan these files with your anti-virus prior to copying them back to your hard drive.

Thank you for replying and for your advice boopme!

I'm sorry it has taken me a few days to reply to your post - I'm working on fixing/saving two different computers right now. I'll give you an update on the situation soon, hopefully.

Take care!
S.