"Unable to scan:this file is a decompression bomb?"

[system]

Can anyone please tell me what this message means after a scan in “scan results?” Thanks! Peace.

[system]

The only issue with this message is the name, it seems to worry users a bit…:

What is a decompression bomb:

@igor post:30

• decompression bomb is just something that unpacks to an unusually big amount of data even though it’s rather small (i.e. has a high compression ratio, for example). It’s nothing to worry about, you are just informed that avast! will not try to unpack the archive (you may not even know that it’s an archive, but it seems like it is) because it may take VERY long to process.

A post by Tech on the subject:

@Tech post:61

By examining 1) the reason given by avast! for not being able to scan the files, 2) the location of the files, you can get an idea of what program they relate to. You may need to expand the column headings to see all the text.

Files that can’t be scanned are just that, not an indication they are suspicious/infected, just unable to be scanned.

Also, the packaging of the file could have some error, or use a non-standard pattern…
avast can’t scan files that are password protected, it doesn’t know the password.

There is nothing to worry about.

[system]

Thanks for your responses. Very helpful. It was a log file BTW. Peace!

[system]

I got that same type of message when Avast tried scanning a Nero image file. After Googling I figured all was well and ignored the warning.

[system]

It’s still a little strange that every *.ISO file is labled as a decompression Bomb.
should the program not be able to scan the files inside an ISO to see if it’s a probelm or not

seems as i have mind on my server and I keep many copies of ISO’s on the server I end up with lots of errors?

[DavidR]

Yes it could, but it would have to unpack the .iso to do that and it could increase the overall file size considerably.

They are hardly errors, just notification of files that haven’t been scanned, many AVs don’t even bother to tell you what files haven’t been scanned, ‘ignorance is bliss’ as you are blissfully unaware of the files that weren’t scanned.

I would rather avast didn’t go down that road of not reporting but this name (which I should like to see changed) is hardly a reassurance that nothing is wrong.

There is nothing to stop you keeping these .iso files in a specific folder and excluding *.iso files in that folder, as there is no immediate danger from an iso file until it is burned to CD, etc. at which time the resident scanner would be scanning newly created files, so if there was malware it should be detected at that point.