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anyone been able to remove EXPIRO successfully?!!!

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#1 gaz73


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Posted 24 October 2013 - 10:41 AM

hi guys,


just came across the expiro virus. totally destroyed the registry as wll as avg. had to reimage. ran avg expiro removal rkill  etc. anyone been able to remove it successfully? if you have please let me know greatly appreciated!!!!! :guitar:

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#2 quietman7


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Posted 24 October 2013 - 11:43 AM

Expiro (Win32/Expiro) is a dangerous family of polymorphic file infectors which encrypts its code differently with each infection...meaning that the viral code inserted into each infected file is unique. Typically the virus infects executable files with .exe extensions in all drives, and steals user login credentials which it sends back to the attacker. It also allows backdoor access and control to the infected computer, lowers Internet Explorer settings and includes functionality to inject malicious code into web pages visited.

File Infector EXPIRO Hits US, Steals FTP Credentials

This attack used exploit kits (in particular Java and PDF exploits) to deliver file infectors onto vulnerable systems. Interestingly, these file infectors have information theft routines, which is a behavior not usually found among file infectors. These malware are part of PE_EXPIRO family, file infectors that was first spotted spotted in 2010. In addition to standard file infection routines, the variants seen in this attack also have information theft routines, an uncommon routine for file infectors.


The virus infects all .exe files (32-bit and 64-bit) on the compromised computer and also on mapped or removable drives (C to Z).

The virus may install Firefox or Chrome extensions and perform the following actions:
monitor browser activity
redirect users to malicious URLs

The virus may steal the following information from the compromised computer:
Product IDs
System volume information
Windows system information
Email addresses
Online banking information, including account numbers

I do not know of any security vendor who will guarantee complete removal of file infectors since 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 afterward, there is still no guarantee the virus is really gone. Since many of the affected files are legitimate critical files required by the operating system, deletion is not a viable option. Even many anti-virus vendors admit that some malicious programs like file infectors cannot be properly disinfected by their products.

File infectors are not on the top of their popularity nowadays (theres not a wide variety of them ITW, but the few active such as Sality or Virut are difficult to defeat). One reason is the frequency of their updates and the complexity of their polymorphism, another reason is the fact, that these viruses are not perfectly tuned. If the file infector should be successful (and transparent to the normal system behavior), it simply should not produce corrupted files (the process crashes will quickly point out whats going on). I will show you some examples of bugs in file infectors (below in this article). The problem is that these bugs often make the infected binaries uncurable...

avast: Buggy file infectors

...You can see some tools claiming theyre able to clean even the most complex infections, but believe me, theres no guarantee to restore the system to its original state. A cleaned file (in my opinion) means a file that has no malicious functionality and does not contain any (even inactive) traces of the infection. My daily practice offers me many files cleaned from the Virut infection with some 3rd party tools, but they still contain significant parts of the infection and are thus detected by our engine....

avast: File infectors part 2

...it is quite interesting to look at modern day polymorphic viruses and whether their propensity to junk files is wholly by accident or whether there is the occassional element of intent involved...a mass infection that leaves behind a large number of irreparably corrupt files can still be very damaging. Some members of the Virut/Vetor family will randomly choose not to leave an infection marker after infection. This leaves the way open to multiple infections (more headaches for anti virus companies) but also increases the chances that the end file will be corrupt...

Sophos: To Junk Or Not To Junk

...In many cases, files cannot simply be deleted as this would affect the stability or even basic functionality of the operating system and other software. Instead, the infected host program must be disinfected by removing the virus code from it and by carefully restoring the original contents and file structure if possible. This means detection and removal are still an issue for antivirus software....

Avira: Cleaning polymorphic infected files

The suggestions in this article are not intended to 100% guarantee removal of all threats...The file infector employs a technique to make sure its corrupted .DLL format will replace the targeted extensions found within the system. When the computer is rebooted it incidentally boots the infected file and continues its advancement throughout the system...

Norton (Symantec): File infector

There are bugs in the viral code. When the virus produces infected files, it also creates non-functional files that also contain the virus...Due to the damaged caused to files...it's possible to find repaired but corrupted files. They became corrupted by the incorrect writing of the viral code during the process of infection. Undetected, corrupted files (possibly still containing part of the viral code) can also be found. This is caused by incorrectly written and non-function viral code present in these files.

AVG: polymorphic infector

...for infected users we have to offer no hope - fdisk - format and re-install is the only solution open to them...

avast: a file infector and why we cannot give false hope!

There are no guarantees when it comes to malware removal and dealing with file infectors as severity of damage will vary. 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 (and days) attempting to repair and remove the infected files.

That's why most security experts say the best course of action is to wipe the drive clean, reformat and reinstall the OS.

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.

miekiemoes' Blog: Virut and other File infectors - Throwing in the Towel?
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#3 gaz73

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Posted 24 October 2013 - 02:57 PM

Thanks quietman! that's what I had to do. a colleague of mine had it but said that avg removal tool (which i'd used also only for it to reappear when I tried to reinstall avg AV again) worked for him. i'm not completely convinced that its been removed for him. I had to do a reinstall. as you said above its the quickest and surest way that its been removed. :thumbup2: 

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