Standard Shield 4.6-652 eats CPU on some EXEs

Avast Free Antivirus / Premium Security
1

Hello !
New to the forum as a poster, but long time user of avast and its forum :wink:

Since last binaries update, I’m having an odd behavior with avast :

  • on some EXEs (as of Zipgenius 6 for example) or on some web pages I got high priority CPU peaks that causes my MP3 or wav files to skip during half to 1 second… After loading the web page or exe, everything returns to normal. If I pauses Standard Shield, all is OK.

  • Running W2K Pro SP4 french box with IE6 SP1, all last critical patches and updates form MS inside…

For some time I though it was ZIPgenius’s fault but Avast seems to be the culprit ?

Hope someone could help me !
Thx in advance,
robert (from france)

2

“On some EXEs” means when starting those executables?
What CPU do you have?
What are your settings of the Standard Shield?

3

yes when launching those executables…
Running an P3-S 1.5 Ghz however pb did not arise before (was using same CPU).
My settings :

  • scanner (basic) options : all sets
  • Scanner (advenced) : scan files on open, always scan
    WSH, scan created/modified files-All files.
  • blocker : Default extension set, formatting, Deny
  • Advanced : nothing set.

Hope this may help…

4

I checked ZipGenius and the delay may be caused by the fact that ZipGenius is rather big and is packed by UPX executable packer. I think the executable packers were not scanned by avast! previously.
While it may take some time to unpack the archives for scanning, I believe it shouldn’t cause audio drop-outs for a good (and well-confiugred) player. The CPU - P3 1.5GHz is quite fast. What do you use to play the files?

You may try one thing: download the UPX packer and unpack the ZipGenius executables. In particular, you’d need the upx125w.zip file; the command-line to unpack the main executable would be
upx.exe -d zipgenius.exe
Some other ZipGenius files are packed as well, e.g. contmenu.dll, zg.exe, … Personally, I don’t consider it a good practise today.

As for the web pages… I don’t think the common web pages should contain that much data to scan, so I really wouldn’t expect any bigger scanning to take.

5

Thx for the analysis. I’ll check the unpacker… I’m using windows mediaplayer 6.4. I tested with windows media player classic and no more skipping during Zipgenius start… I thought that WMP 6.4 was the most cpu friendly player :o very surprising… may be time to completely switch to WMP Classic ???

Also maybe an UPX bug ? will check UPX site. Thx for your quick answer :slight_smile:

6

No, it’s certainly not a UPX bug, just that avast! needs a while to unpack it (and it’s questionable to use it to pack half of ZipGenius files).

As for the player… well, I rather had something like WinAMP on mind - it makes it possible to run the (MP3) decoder in a high priority thread, and also to configure output buffering - so that you can have e.g. a few seconds of sound decoded in advance. That way, the drop-outs are quite unlikely.

7

I tried configuring such a buffering in WMP 6.4 at no avail… However WMP classic works perfectly out of the box…

I unpacked all zipgenius files using latest UPX and bingo, I works now like a charm ! :slight_smile: