avast! gets "stuck"

[avastman]

Hi.

Since upgrading to v4.5, during thorough disc scans, after scanning several thousand files, avast! hangs, although CPU usage continues.  It's as if it's "stuck" on a file, however, it does not always get stuck at the same place (e.g. sometimes in MS Office install dir, sometimes in MS Streets & Trips install dir, etc.), and a follow-up folder scan seems to run OK.

Anybody else experiencing similar problems?

avast! version: 4.5.549
VPS version: 0450-1, 12/09/2004
system: WinXP-Home-SP2

Thanks!

[igor]

I guess it actually gets stuck always on the same file, but because the display is not updated for every file, the last shown file/folder may be different every time.
Recently, there have been a few similar problems - but until now, we have been unable to get access to the "bad" file, so we couldn't fix it

Right now, I suspect the file Data\USAARTS.ITS from the MS Streets & Trips folder. Could you please check if you have such a file there? How big is it? What Internet Connection do you have (i.e. would it be possible for you to submit the file to us, e.g. using FTP)?

Thanks!

[avastman]

Nice!  You have identified the problem file!

I do have a file USAARTS.ITS and avast! hangs when scanning it.  Furthermore, I temporarily removed the file and successfully completed a full disc scan.

I can FTP USAARTS.ITS to you (14 MB zipped) if you tell me where to upload it.

I must admit, I'm curious as to how you could know what file was causing the problem, but yet were unable to fix it?

Thanks for your quick and ACCURATE response!

[Eddy]

I'm curious as to how you could know what file was causing the problem

Real easy. Someone else is having the same problem with that file. If you use the search option on this board, you can find the thread

[avastman]

I did a search for "usaarts" in all forums, and all I get back is my own thread...  Do you get others?  If so, please post links, because they don't show up here!

Thanks.

[igor]

I talked about it with somebody else via e-mail, and there was a similar problem in MS Autoroute.
I just sent you a private message with the login info.

Thanks!

[igor]

Thanks for the file!
I'll check it tomorrow, as soon as I get to my office.

[igor]

OK. I checked the file... and found out the following:
avast! actually doesn't get stuck - but it takes very long to open the file (which is considered a CHM archive by avast!). The reason is the way how CHM unpacker works - on opening, all its content is extracted to TEMP file and scanned afterwards; unfortunatelly, avast! doesn't show the progress during the extraction, so it seems to be stuck.

The problem with this file is that in contains a huge amount of files (close to 650 000). Of course, the files are small - but it takes pretty long to extract them (besides, it may cause some troubles on FAT partitions... creating over 600 000 files in one folder might not be the best idea). I tried to scan it with another AV program and it took close to an hour to finish (P3 1.5GHz).

So, I'm not sure how to solve this problem. I will see if it's possible to identify this type of files somehow and avoid recognizing them as a CHM archive. This way, however, other similar (and possible small and avast!-friendly) files won't be scanned inside. Or, we may try to detect is as a "decompression bomb" and skip the scan after a part of the files is extracted... don't know  

For now, I suggest to put the file or folder into the list of avast! exclusions - so that avast! will not scan it at all.


Btw, newer versions of MS Streets and Trips changed the format of their data files slightly, so they don't suffer from this problem.

Sorry for the troubles.

[avastman]

THANK YOU!

...  for the quick analysis and excellent explanation.

I will add the file to avast!'s exclusion list.

I look forward to seeing whatever solution you come up with in a future version of avast!!