JS:FakeCodec-G Alert from Avast!

Hi everyone,
I’m new to all of this, although I do have some IT skills. Five times over the last 10 days I’ve gotten an alert from Avast! that there’s a sign of a Trojan virus when I close out Mozilla Firefox. Tonight. I tracked it down to the FOX news Website. When I close out the FOX site the Avast! waring screen comes up and I follow the instructions and move the file to the chest.
Here’s exactly what the Avast! Log says:

Sign of “JS:FakeCodec-G [Trj]” has been found in “C:\Users*****\AppData\Local\Mozilla\Firefox\Profiles\5y29skyi.default\Cache_CACHE_003_” file.

I have Windows Vista. I use the free Avast! home edition, but also, I keep the Windows defender updated, and keep up on patches etc. I also use the Microsoft Malicious Software removal Tool and Avast Root Kit Scan.

After the first time and again two days ago, I ran a boot level scan (the long scan that goes through all the files etc.) through Avast! which came clean.

I’ve run multiple full scans with Avast! and Defender,and the Microsoft MSRT. I never get any hits for anything.

So what do you guys think? Am I infected in a way that’s not getting caught by all this, or is Avast! warning me before the infection happens? In short, is there more I need to do, or should I just go about my business and let Avast! work its magic?

Thanks very much for any info,
Philo

Sorry, I forgot to add, every time this Trojan has popped up it’s in the cache-3 file and only when I use Firefox. I do not get this from IE ever.

Hello Philo,

just try cleaning up your ff’s cache.

for that (firefox 3.5.3),

go to tools > clear recent history > time range to clear : everything > details > select all options available there > hit clear now.

post back.

nmb

Really? That’ll do it then, just dumping the cache? I have Firefox set to do that automatically every time I close it. I generally don’t have browsers save any info.

I asked you to try doing that, if you can read my post again.

no one knows the exact things to be done. we have to start trying.

next one is scan with malwarebytes(mbam).

update and do a quick scan, remove any detected items, reboot if required and post back the log.

also do a scan using superantispyware(sas). dont worry about the tracking cookies reported, let sas deal with it.

post back

nmb

ran the malwarebytes, no infected files. Looks good. Will keeping malwarebytes interfere with Avast!?

malwarebytes does not interfere with avast. both works good. you can use mbam to scan once every three days.

what about sas?

did you try a scan with it?

nmb

Sorry, I had to get some sleep.

Yes, I did use both Malwarebytes and sas. Nothing came up with malwarebytes. Just a couple tracking cookies with sas. Other than those, the system seems to be clean. Unless there’s something else.

If not, thanks very much for your help.

~Philo

I suggest you use CCleaner (Slim Version).

Thank you Philo, for asking the original question and getting this forum going.
Thank you Avast! Evangelist for your suggestion to use Malwarebytes.
I had the exact same problem as Philo. What I found was an infected video file I had downloaded with Real player. I don’t think Real player had anything to do with it but I wanted to give all details involved.
I noticed that every time I played the particular file, (after much trial and error) then shut FF down, Avast would come up with the same warning Philo got. I even deleted the “CACHE_003_” Philo referred to.
However after scanning with Avast, Avg, and Malwarebytes, none of them showed anything infecting the aforementioned file.
I tried to delete the questionable file, to no avail. A message kept coming up saying file was in use by another user or program…hmmmm.
This is where Malwarebytes came to the rescue.
Under the headding tab “more tools” I found FileASSASSIN option, and sure enough that is what it did :).
I hope this small contribution has helped others as you all have helped me.

Thanks,
Racecar599