Virut and other File infectors - Throwing in the Towel?

I actually wanted to blog about this last week, but didn't find the time yet...
In the last couple of weeks, I noticed a HUGE increase of Virut present on computers. As a matter of fact, 30% of the infected computers I analyzed were infected with Virut. This is bad, really bad... :-(

Virut is a Polymorphic File Infector that infects .EXE and .SCR files. It opens a Backdoor by connecting to a predefined IRC Server and waits for commands from the remote attacker - for example to download/run more malware on the compromised computer. Emails may be harvested as well.
This latest variant may also search for htm, html, asp and php files on the drives and modifies them by inserting an iframe that points to a malicious website. So you can already imagine what may happen if the owner is a webdesigner and uploads the infected webpages.
An excellent write up on this latest variant (and previous one) can also be found here (by Nicolas Brulez): http://securitylabs.websense.com/content/Blogs/3300.aspx

Disinfection of the infected webpages should be easy - it's just a matter of deleting the iframe script in it.
The disinfection of the infected exe and scr files is something else...
Since Virut infects legitimate files, the files may not be deleted, but disinfected instead. And that's where the problems start...
Virut was known to be a buggy Virus in the past and it appears that this hasn't changed yet. We've seen this with other File infectors as well: To Junk Or Not To Junk.

And because of that, Virut may misinfect a proportion of executable files > result > corrupted file.
The same applies for other File infectors such as Sality.

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.
And even though an Antivirus is able to disinfect the files, in a lot of cases, many files will be corrupted anyway > result > many programs won't work > loads of errors > corrupted Windows + there's still no guarantee that the Virus is really gone.
So why bother to clean this if a format and reinstall is the fastest and especially the safest solution?

And that's why I am blogging about this in the first place, especially since Virut is a very common infection nowadays. It's a pity to see that so many people are struggling with it and whatever they try, nothing helps. Then they ask for support via the forums and in a lot of cases, the one who is helping/guiding won't give up either and posts a new set of instructions to deal with this one.
Unfortunately another failure as result, so again, new instructions are posted... and this may go on and on...sometimes for weeks....
Is this responsible?
I'm not saying it fails everytime, but from what I have seen so far and especially if you're helping someone else with this infection... don't guarantee them a "clean" and errorfree computer afterwards .

In anyway, that's how I see it. Imho, 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.
Many people may see this as "giving up", but I see this different.
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.

Virut is back again - sigh

Virut (PE_VIRUT.XZ in this case) is back again.

This one "spreads" via email with subject: "Important update from Microsoft Windows XP/2003 Professional Service Pack 2(KB946026)" or "Critical Security Update for Microsoft Windows (KB946026)".
From: Micrisoft Corporation 2008 ©
The link to the supposed WINDOWS-KB946026-X86-ENU download from Microsoft for the fix goes to this address:

URL=hxxp://xxxxx.net/upload/WINDOWS-KB946026-X86-ENU.EXE.exe



Note: This is NOT the legitimate download from Microsoft here. The legitimate WINDOWS-KB946026-x86-ENU.EXE does NOT have above "Windows icon", but has the default exe file icon instead.
The file from the link in the mail doesn't install any updates, but installs Virut, a polymorphic appending file infector.

This one attempts to infect any accessed .exe or .scr files by appending itself to the executable. It contains an IRC-based backdoor that provides unauthorized access to infected computers.

Luckily, since this is an older variant - most Antivirus Scanners *should detect and delete it immediately. That's why it's really important that your Antivirus Scanner is up to date!

In case you are someone who just loves to click links in mails - even though your Antivirus Scanner alerts you - or you have an Antivirus where the trial already expired for a couple of months - or don't even have an Antivirus installed... Well, I can assure you, you'll really regret it if you open/run the file. Mainly because this is a file infector which infects legitimate exe and scr files, so these files may not be deleted, but disinfected instead. And a common problem I see with Virut is that in some cases (some variants), it contains a bug in the code and as a result it may misinfect a proportion of executable files. And because of that, an Antivirus Scanner cannot disinfect it properly either > result > a corrupted file.

That's why, if I guide someone with Virut present and their Antivirus cannot properly disinfect it, then I recommend a format and reinstall. Unless the person knows what files are corrupted and knows how to replace them with a clean one. But then again, it's no guarantee that everything will work properly again and Virut is gone.
A format and reinstall in this case is still the fastest and especially the safest solution.

So once again, make sure your Antivirus is always up to date!

Source.

Please disable Autorun asap!

We see an increase in USB-Based Malware Attacks lately - See here and here for more info.
Unfortunately, in the last few weeks, I have seen many cases where the enabled autorun feature caused A LOT of problems afterwards. This means that many are not aware of the dangers yet.
For example.. Some scenarios I have seen in the last couple of weeks are:

* Computer gets infected with Win32/Sality.NAR (NOD32 detection). This is a polymorphic file infector which searches local and network drives for files with the .exe extension and infects them by adding a new section that contains the viruscode.
It also copies itself into the root folders of removable drives using a random filename and creates an autorun.inf file to make sure it runs whenever it is inserted into another computer. It also disables most AV scanners by terminating their services/processes, disables Taskmanager, disables Regedit and much more to prevent it being detected or disinfected.
In this case, the user had an USB flashdrive and used it to transfer removal tools etc in order to remove this infection, since no scanners would work. What happened was, since this virus also spreads via removable media, his USB flashdrive became infected > result > His other computer was infected as well!

* Computer gets infected with W32/AutoRun-OY - This one also spreads via removable drives. This computer is used at home and every user has its own account. Mom, dad, son and daughter. Son loves to play games, but also loves to download games + cracks via illegal resources.
And that's how the computer at home gets infected with W32/AutoRun-OY. No detection since the Antivirus application that was installed was only a trial and was already expired for more than a year. Dad works for a big company and he tranfers his database+files from the computer at work to an USB flashdrive so he can proceed with his work at home.
The usb flashdrive gets infected when he inserts it into the infected computer at home. Since no scanner (because it's outdated) gives an alert and blocks the malware, there's no sign that the computer + Flashdrive is infected.
Dad goes back to work, inserts the flashdrive into his computer at work and... it gets infected as well. No alert, nothing! It appears that the computer at work didn't even have an Antivirus installed !! And, worst part of all was... Virut was also present! See here for more info. This is imho a lost case, and especially for business owned computers, it is irresponsible to clean this up manually. Format and reinstall is the fastest and especially the safest solution here.
So, who is to blame here? Imho, everyone is. The son who is responsible for visiting illegal sites in order to download his games + cracks, plus the fact that the Antivirus was outdated, plus the fact that dad uses an USB flashdrive containing corporate information and inserts it into the personal computer (see here how to protect your data), plus the fact that the computers at work didn't even have any protection/AV installed.
Anyway, this is so irresponsible, especially when company owned computers are involved.

* And today, I have another case where someone gets infected with W32/AutoRun-OY, where mom uses an usb flashdrive to transfer files to use at work and is already complaining about the fact that there are "problems". This thread is still in progress and I really hope this isn't a lost case.

No wonder the Military bans disks and USB drives

This appears to be a common problem nowadays - that's why it is so important to prevent spreading similar infections by disabling Autorun.

To disable autorun, please read the following tutorials:

http://www.howtogeek.com/howto/windows/disable-autoplay-of-audio-cds-and-usb-drives/ (applies for XP Pro since XP Home has no gpedit.msc present)
http://www.engadget.com/2004/06/29/how-to-tuesday-disable-autorun-on-windows/ (aplies for XP Home. Same can be used for XP Pro)
http://www.howtogeek.com/howto/windows-vista/disable-autoplay-in-windows-vista/ (applies for Vista)

Some malware removal tools already disable Autorun by default. Don't complain about this. This is an extra security measure and you should have it disabled. If you really want to enable this again - then it's your own responsibility. Don't complain afterwards if you get infected and are responsible for infecting a lot of other computers as well.

Update: Extra instructions to disable autorun (by US CERT) can be found here.