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Sudden virus outbreak


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#1 Lyxs

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Posted 06 June 2011 - 09:04 PM

Hi, i am new to this forum and i'm posting because i have a sudden virus outbreak on my computer and i'm having a hard time dealing with it. I found this forum while googling for information on this virus, so i'm posting in hope that we can solve this.

Today i got infected by the virus Win32:Ramnit-B and i suspect it came from a pen drive. Before i plugged the pen, two other pcs also used it and neither of them shows any apparent signs of infection.
After i plugged the pen and tried to install a file, avast blocked it, and i proceeded to do a quick system scan to see if any other files were infected. The result showed over 11000 files infected, and after attempting to repair the pc blocked. I restarted it and scheduled a boot scan from avast, proceeding to restart again. I tried to Repair or Move to chest on the first few infections found, but nothing worked. That left me with the option to delete, wich i didn't because that would mean deleting way too many files from my hardrive. While i was scanning i noticed most of the infections were found on program folders.
So i'm writting here in hope that someone can help me fix this problem.
I am running Windows 7 on a toshiba laptop.

Edit: I've just finished a full system scan with avast and apparently most of the infections are "VBS:Exedropper-gen", i'd say about 80%.

Edited by Lyxs, 07 June 2011 - 09:37 AM.


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#2 Lyxs

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Posted 10 June 2011 - 04:12 PM

Since i can no longer edit the post, and three days have passed since i posted the original thing, i'm giving a status update of the situation before posting here.
A
Since i got infected i've been googling for information and solutions to this. From what i've found, ramnit infects .exe, .dll and .htm mostly, thats why the infections were mainly on the program folders, and programs won't run ( damaged .dll ). I've installed and ran MBAM wich found about 4 infected files and cleaned them. I believe that stopped the infection from spreading. Now i have a program called "Dr.Web Cureit" wich scans for infected files and cleans them. I was 4:30 hours into the scan (and still not 50%) when i had to stop the scan. It found lots of infected files and repaired/moved them. Still the programs i have installed wont work, but i managed to reinstall one of them already, as a test, and it worked fine. So now i have in schedule a full Dr.Web Cureit scan, scan again with avast and maybe Kaspersky eScan, and then a CCleaner scan.

I know a format is the safest and easiest way to get rid of a virus like this, but i prefer saving it as a last resort. If there's a way of cleaning the virus, i'll try that first.

So, for now i want to know if there are any other things you might suggest to get me rid of this virus and getting my pc running clean agian.

#3 boopme

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Posted 10 June 2011 - 09:06 PM

Sorry you waited so long. This IS the last resort.

I'm afraid I have very bad news.

Win32/Ramnit (and related variants) is a dangerous file infector with IRCBot functionality which infects .exe, and .HTML/HTM files, and opens a back door that compromises your computer. Using this backdoor, a remote attacker can access and instruct the infected computer to download and execute more malicious files. The infected .HTML or .HTM files may be detected as The infected .HTML or .HTM files may be detected as Virus:VBS/Ramnit.A or VBS/Generic. Win32/Ramnit.A!dll is a related file infector often seen with this infection. It too has IRCBot functionality which infects .exe, .dll and .HTML/HTM files and opens a back door that compromises your computer. This component is injected into the default web browser by Worm:Win32/Ramnit.A which is dropped by a Ramnit infected executable file.

-- Note: As with most malware infections, the threat name may be different depending on the anti-virus or anti-malware program which detected it. Each security vendor uses their own naming conventions to identify various types of malware.With this particular infection the safest solution and only sure way to remove it effectively is to reformat and reinstall the OS.

Why? The malware injects code in legitimate files similar to the Virut virus and in many cases the infected files (which could number in the thousands) cannot be disinfected properly by your anti-virus. When disinfection is attempted, the files often become corrupted and the system may become unstable or irreparable. The longer Ramnit.A remains on a computer, the more files it infects and corrupts so the degree of damage can vary.

Ramnit is commonly spread via a flash drive (usb, pen, thumb, jump) infection where it copies Worm:Win32/Ramnit.A with a random file name. The infection is often contracted by visiting remote, crack and keygen sites. These type of sites are infested with a smörgåsbord of malware and a major source of system infection.

In my opinion, Ramnit is not effectively disinfectable, so your best option is to perform a full reformat as there is no guarantee this infection can be completely removed. In most instances it may have caused so much damage to your system files that it cannot be completely cleaned or repaired. Security vendors that claim to be able to remove file infectors cannot guarantee that all traces of it will be removed as they may not find all the remnants. If something goes awry during the malware removal process there is always a risk the computer may become unstable or unbootable and you could loose access to all your data.

Further, your machine has likely been compromised by the backdoor Trojan and there is no way to be sure the computer can ever be trusted again. It is dangerous and incorrect to assume the computer is secure even if your anti-virus reports that the malware appears to have been removed.

Many experts in the security community believe that once infected with this type of malware, the best course of action is to wipe the drive clean, reformat and reinstall the OS. Please read:

Whenever a system has been compromised by a backdoor payload, it is impossible to know if or how much the backdoor has been used to affect your system...There are only a few ways to return a compromised system to a confident security configuration. These include:
• Reimaging the system
• Restoring the entire system using a full system backup from before the backdoor infection
• Reformatting and reinstalling the system

Backdoors and What They Mean to You

This is what Jesper M. Johansson at Microsoft TechNet has to say: Help: I Got Hacked. Now What Do I Do?.

The only way to clean a compromised system is to flatten and rebuild. That’s right. If you have a system that has been completely compromised, the only thing you can do is to flatten the system (reformat the system disk) and rebuild it from scratch (reinstall Windows and your applications).




If you insist on trying to fix this infection instead of following our advice to reformat and reinstall your operating system, there are some tools and various rescue disks available from several anti-virus vendors. Keep in mind there is no guarantee the repair will be successful and you may need to try more than one. Even vendors like Kaspersky say there is no guarantee that some files will not get corrupted during the disinfection process. This means that infected executables and system files can become unusable after attempting to repair them and there's still no quarantee the virus is really gone. Since many of these are legitimate critical files required by the operating system, deletion is not a viable option. This destructive behavior may be by design as explained in File Infectors: To Junk Or Not To Junk.

In my experience, users may find their system performing better for a short time after attempted disinfection only to have it become progressively worst again as the malware continues to reinfect thousands of files. Some folks will try every tool or rescue disk they can find in futile attempts to repair critical system files. If something goes awry during the malware removal process the computer may become unstable or unbootable and you could loose access to all your data. In the end most folks end up reformatting out of frustration after spending hours attempting to repair and remove the infected files.

Bleeping Computer DOES NOT assume any responsibility for your attempt to repair this infection using any of the following tools. You do this at your own risk and against our advice.

If your computer is bootable, disinfection can be attempted through a combination of the following tools:These are links to Anti-virus vendors that offer free LiveCD or Rescue CD utilities that are used to boot from for repair of unbootable and damaged systems, rescue data, scan the system for virus infections. Burn it as an image to a disk to get a bootable CD. All (except Avira) are in the ISO Image file format. Avira uses an EXE that has built-in CD burning capability.

If you are not sure how to burn an image, please read How to write a CD/DVD image or ISO. If you need a FREE utility to burn the ISO image, download and use ImgBurn.
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