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MS Security Essentials detected Virus:Win32/Ramnit.AF


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#1 Mithos

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Posted 13 November 2011 - 09:39 PM

Hi,
today, Microsoft Security Essentials detected multiple instances of Win32:Virus/Ramnit.AF, and one of Trojan:WinNT/Ramnit.gen!A.

It seems to be replicating, and other topics suggested I need to do a reformat.

Do I need to do a reformat?

My laptop comes with a recovery partition...what if that's infected too? :s

Advice welcome.

thanks

edit: Should I also destroy my data partition? Should I order a set of recovery disks from HP (laptop manufacturer) instead of using the recovery partition?

Edited by Mithos, 13 November 2011 - 10:05 PM.


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#2 quietman7

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Posted 13 November 2011 - 11:02 PM

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 security expert miekiemoes has to say: Virut and other File infectors - Throwing in the Towel?

If I guide someone with Virut (or any other File Infector) present and their Antivirus cannot properly disinfect it, then I recommend a format and reinstall...dealing with such infections is a waste of time and that's why I prefer the fastest and safest solution - which is a format and reinstall...After all, I think it would be irresponsible to let the malware "stew" (download/spread/run more malware) for another couple of days/weeks if you already know it's a lost case.

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).



Important Note:: If you're using an IBM, Sony, HP, Compaq, Toshiba, Gateway or Dell machine, you may not have an original CD Disk. By policy Microsoft no longer allows OEM manufactures to include the original Windows CD-ROM on computers sold with Windows preinstalled. Instead, most computers manufactured and sold by OEM vendors come with a vendor-specific Recovery Disk or Recovery Partition for performing a clean "factory restore" that will reformat your hard drive, remove all data and restore the computer to the state it was in when you first purchased it. Please read Technology Advisory Recovery Media.

If the recovery partition has become infected, you will need to contact the manufacturer, explain what happened and ask them to send full recovery disks to use instead. If you lost or misplaced your recover disks, again you can contact and advise the manufacturer. In many cases they will send replacements as part of their support.
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#3 Mithos

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Posted 14 November 2011 - 05:53 AM

Thanks.

I guess I'll reformat [to get rid of everything asap - I kind of need an excuse to wipe, anyway], then do a full scan of the main partition and the recovery partition.

I should be able to keep anything that isn't a .exe, a .dll or a .html-style document, right?
ie, videos and music? Or shall I just nuke it all, to be safe?

Is there a specific tool to scan flash drives? or shall I just use MS Security Essentials.
[edit] Is there a tool to scan Windows drives [or flash drives] for Windows viruses from a Linux (Ubuntu) boot?

Edited by Mithos, 14 November 2011 - 05:57 AM.


#4 quietman7

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Posted 14 November 2011 - 07:13 AM

Caution: If you are considering backing up data and reformatting or doing a factory restore with a vendor-specific Recovery Disk/Recovery Partition due to malware infection, keep in mind with file infectors, there is always a chance of backed up data reinfecting your system. If the data is important to you, then you can try to salvage some of it but there is no guarantee so be forewarned that you may have to start over again afterwards if reinfected by attempting to recover your data. Only back up your important documents, personal data files, photos, music, videos to a CD or DVD drive, not a flash drive or external hard drive as they may become compromised in the process. The safest practice is not to backup any executable files (*.exe), screensavers (*.scr), dynamic link library (*.dll), autorun (*.ini) or script files (.php, .asp, .htm, .html, .xml) files because they may be infected by malware. Avoid backing up compressed files (.zip, .cab, .rar) that have executables inside them as some types of malware can penetrate compressed files and infect the .exe files within them. Other types of malware may even disguise itself by hiding a file extension or adding to the existing extension as shown here (click Figure 1 to enlarge) so be sure you look closely at the full file name. If you cannot see the file extension, you may need to reconfigure Windows to show file name extensions. Then make sure you scan the backed up data with your anti-virus prior to to copying it back to your hard drive.

If your CD/DVD drive is unusable or there isn't one installed, another word of caution if you are considering backing up to an external usb hard drive as your only alternative. External drives are more susceptible to infection and can become compromised in the process of backing up data. I'm not saying you should not try using such devices but I want to make you aware of all your options and associated risks so you can make an informed decision if its worth that risk.Again, do not back up any files with the following file extensions: exe, .scr, .dll, .ini, .htm, .html, .php, .asp, .xml, .zip, .rar, .cab as they may be infected.


USB Anti-virus Tools:Flash/External Drive Scanning Tools:
  • Malwarebytes' Anti-Malware. For usb flash drives and/or other removable drives, perform a Full scan. The option for a Flash Scan will analyze memory and autorun objects but that option is only available to licensed users in the paid version.
  • Norman Malware Cleaner. For usb flash drives and/or other removable drives to scan, use the Add button to browse to the drives location, click on the drive to highlight and choose Ok.
  • Dr.Web CureIt. Choose Custom Scan after the Express Scan has finished to add your usb or external drive to the scan.
  • McAfee Avert Stinger Tool.
Tip: As an extra precaution, hold down the Shift key when inserting the drive until Windows detects it to keep autorun.inf from executing if it is present. Then perform your scans.

USB Protection Tools:

Edited by quietman7, 14 November 2011 - 07:16 AM.

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