Issue & Fix- following symbolic links/shortcuts to another drive in custom scan

An Issue with avast! 4x & 5x following symbolic links back to the host OS when scanning an offline OS.

In other words…

I pull a hard drive from a Windows Vista computer, and put in in an external enclosure to preform an offline scan with my host computer (Windows 7)
avast! 4x or 5x is set to scan just the offline OS hard drive (drive Y:), using a custom scan.
When avast hits the symbolic link for Documents and Settings located on the offline OS drive, at “Y:\Documents and Settings” , it follows the link back to my host computers Users folder, at “c:\Users” - even though I selected only drive Y: to be scanned through “Interactive Selection”.

The result… and additional 60min to my scan while it checks my host computers 100+ GB “users” folder

This issue has been around since at least version 4x, and effects both Vista and Windows 7 (as either the host or the offline system).

The fix… in your custom scan settings, add an Exclusion to the symbolic link "Y:\Documents and Settings"

I was surprised to not see this fixed in avast! 5x, and also surprised to not see any mention of it in the forums here. I suppose if I had taken the time to contact customer support, it may have been fixed. But I thought I might at lease save some other users some time by posting the issue and the fix here… I waited through several excessively long scans before I even realized what was going on.

It wasn’t “fixed”… because it’s not considered a bug.
OK, I admit the behavior is strange for you - when scanning an external harddrive attached to a different computer. However, I’d say it’s quite a rare scenario. The majority of users will scan their own drives (consider e.g. scanning a folder using the Explorer extension) - without knowing there are any links below (usually even without knowing what a link is). I’d say there would be quite surprised if the results were “0 files scanned”… because they’ve just scanned a link (but in Windows Explorer they see quite a few files “inside”, of course).

I’d agree it is not a very common scenario. But, it strikes me as being a problem because it causes a considerable performance hit when it does occur. It was taking 3-4 hours to scan a 60GB drive via ESATA- and I couldn’t figure out why it was taking so long untill I sat there and watched the scanner progress for almost an hour. For someone who doesn’t take the time to do that, that’s would be a pretty negative experience with the program.

I’ve found that doing an offline scan like that is a good way to make sure that I don’t miss any root kits or active malware when cleaning up a system- and I’d thought that others do the same. But then again, i guess the lack of any information on it in the forum would be a good indication of how often it occurs. And the scenario you explain would probably occur a heck of a lot more often than mine. I wonder if it would be possible to put “do not follow links” as an option under scan parameters, in the custom scan settings?