Avast dramatically slowing down opening of zip files?

[websave]

Hello, I first had issues with avast using too much CPU now but I fixed it. Now I have problems with it slowing down openings of ZIP files. I downloaded Eclipse SDK and when I tried to open it in WinRAR, it took 5 minutes to open. When I disabled avast, it opened in seconds. My PC CAN handle avast. It has an AMD FX 8 Core, 8 GB of Corsair RAM, and a WD Black. My settings in avast File shield are: All packers, High sensitivity, Use code emulation and test for PUPs.

[polonus]

Report this right-on and send the zip file in question to virus AT avast dot com (password in the mail message)
and let the avast team members look at the issue.
Could be a sandbox issue, but let them look into it,
also mention a link to this webforum post.
Hope your issue will soon be settled,

polonus

[websave]

Report this right-on and send the zip file in question to virus AT avast dot com (password in the mail message)
and let the avast team members look at the issue.
Could be a sandbox issue, but let them look into it,
also mention a link to this webforum post.
Hope your issue will soon be settled,

polonus

It happens with all ZIP files. I know Eclipse SDK is safe because it is used by many Android developers and comes with the Android ADT by Google.

[Pondus]

try going back to default avast settings...

[websave]

try going back to default avast settings...

I select repair in avast setup, right? Also, shouldn't avast warn you about slowing opening of ZIP files? What type of packers do you suggest I check?

[RejZoR]

The same will happen with any antivirus. When files are unpacked from archive, they are usually observed for the first time so cache mechanism cannot kick in. And that's why it will unpack files slower than usual.

Only way to get around this is to disable "Scan when writing" in the File System Shield. What this means is that files won't be scanned when copied to the HDD, they will only get scanned on execution (when you actually erun or open them). This will however mean that files in transit won't be thoroghly checked and also i'm not sure how it would behave with file infectors if only the payload would get detected during file modification and not during file read process.

[igor]

No, Scan when writing shouldn't be disabled (though yes, it would probably "fix" the behavior as well) - unpacking ZIP archives in File System Shield should be (which is the default). It's not a good idea to unpack non-default archives in File System Shield.

[iroc9555]

What type of packers do you suggest I check?

Default Packers in FSS are:

Self-extracting DOS executables
Self-extracting Win32 executables
Droppers
NTFS streams

[websave]

What type of packers do you suggest I check?

Default Packers in FSS are:

Self-extracting DOS exsecutables
Self-extracting Win32 exsecutables
Droppers
NTFS streams

Thanks! 

[iroc9555]

Thanks! 

You are welcome.

BTW you can set up Windows Explorer Scan to its highest configuration and scan any file before opening it with WinRAR just by right clicking on it and choosing scan with Avast!.

To scan an individual file, just right-click the file to open the context menu and select the option "Scan <filename>".

To add this scan to the list of pre-defined scans on the Scan Now page, go to the program "Settings" and check the box "Show special scans in avast! user interface". You will then be able to access and adjust the scan parameters as required.

[RejZoR]

I don't think avast! scanning the ZIP file is the problem, it's the actual files extraction process. There is no way in bypassing that without compromising the security.

[iroc9555]

I don't think avast! scanning the ZIP file is the problem, it's the actual files extraction process. There is no way in bypassing that without compromising the security.

Agree; Nontheless, websave had FSS set to scan all Packers, this will take some time for Avast! to check when running WinRAR. If he scan the .zip file itself beforehand, and having both options on Persistance cache turn on in Windows Explorer Scan, it will decrease time when opening the file with WinRAR. It took me a little over 2 min to scan 2 Gig .zip file.