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Symantec reporting W32.Ramnit!html


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#1 PSStu

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Posted 19 April 2011 - 09:16 AM

Afternoon all,

Hoping someone might be able to help with a PC with a persistent W32.Ramnit!html infection on an XP Pro machine. The PC had an "IQ Challenge" program installed (since removed). Symantec Endpoint Protection detected numerous instances of W32.Ramnit.B!inf which seemed to be cured after numerous scans in safe mode and deletion of files created after the infection began. There was also W32.Ramnit!html detected with three processes labeled as iexplorer.exe appearing immediately after logging in. After a reboot, there were numerous .tmp files flagged with W32.Ramnit!html, however since quarantining them they have not been detected again by Symantec (latest virus defs). I note two iexplorer.exe processes now appear each time Internet Explorer is opened. In addition, MalwareBytes (latest update) detected the following post-reboot:

c:\documents and settings\administrator\start menu\Programs\Startup\xcwagmkf.exe

c:\documents and settings\administrator.pc\start menu\Programs\Startup\xcwagmkf.exe

c:\documents and settings\user\start menu\Programs\Startup\xcwagmkf.exe

c:\program files\000\xcwagmkf.exe

c:\program files\er\xcwagmkf.exe

All of which have now been deleted and any mention of them has been unpicked from the registry.

I've looked for various removal instructions and tools, however I am unable to find any specific to this problem as many of the typically found files seem not to be there in this instance.

I have tried scans with Malwarebytes, Symantec Endpoint Recovery Tool, BitDefender Online, ESET Online, SuperSpyware, ComboFix and DrWeb CureIt, and none detect malware/infection, however Symantec Endpoint Protection is still detecting numerous .tmp files (beginning "DWHD") flagged with W32.Ramnit!html. I am also still getting two instances of iexplorer.exe within Task Manager each time IE8 is opened, even with a single tab or window open.


Any help would be gratefully received.

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#2 quietman7

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Posted 19 April 2011 - 09:27 AM

I'm afraid I have very bad news.

Win32/Ramnit (and other variants) are dangerous file infectors 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).


Important Note:: If your computer was used for online banking, has credit card information or other sensitive data on it, all passwords should be changed immediately to include those used for banking, email, eBay, paypal and any online activities which require a username and password. You should consider them to be compromised and change passwords from a clean computer, not the infected one. If not, an attacker may get the new passwords and transaction information. Banking and credit card institutions should be notified immediately of the possible security breach. Failure to notify your financial institution and local law enforcement can result in refusal to reimburse funds lost due to fraud or similar criminal activity. If using a router, you need to reset it with a strong logon/password so the malware cannot gain control before connecting again.
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