Wednesday, August 09, 2006

Virus Trouble

I had a spot of bother on my PC last night with a virus. Out of the blue my free version of AVG sprang up and announced that I had a Trojan horse- Downloader.Agent.ETP in the Windows system file wininet.dll. AVG "healed" the item by removing it to the virus vault- although it took a few restarts and then me deleting it myself in Safe Mode to actually stop the pop up warnings.

The problem is that AVG and Symantec have no record of a virus with that exact name- and wininet.dll is an actual system file that's required by several applications to start and connect to the internet. I was beginning to worry when Ad-aware and then my Nero DVD-writing software wouldn't start up- it's been a while since my last back up! When I tried a System Restore it wouldn't work either- that program needs the wininet.dll to start up too.

Thanks to a very useful site called Dll-Files I was able to grab an untainted version of wininet.dll and put it back in the System32 folder- although it took a couple of attempts to realise that the infected version was being stored in the dllcache folder also. It kept replacing my clean version; it took a few restarts for me to catch that one and delete it too.

After a tense time my system finally started up without any warnings about programs failing to initialise- and Ad-aware and Nero worked. Thank the heavens.

I'm still not sure how or where the virus came from; or if it's some sort of false positive from my AVG. In any event I at least know now where to find easy copies of dll files- and my second hard drive also has a copy of Windows installed. If the virus had crippled my system I would have been able to swap the jumpers on my HDDs and boot off the second one; it also has Nero installed and ready to run.
Always pays to have a plan b.

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