I just had a Win32:Lethic[Trj] trojan. Damn nasty thing, turns your computer into a spamming base. Some info about it: http://remove-malware.net/how-to-remove-win32lethicaa-trojan/
Now Avast has successfully indentified and blocked the .exe files it created in c:\documents and setting\username\local settings\temp folder but the main thing remained unnoticed. As the link says it inserts a code in the registry pointing to the C:\RECYCLER folder. And there it was, [random chars].exe, undeletable. I made a full system scan, nothing found. Then I tried to make a folder scan and whoops: RECYCLER folder doesn’t even show up! Can’t select it and apparently even the complete scan skips it. At the end I could delete the file only with ESET’s online scanner. Shame.
Also, Avast did not identify that the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon “Taskman” = “%RECYCLER%\S-1-5-21-0243556031-888888379-781863308-1455\psysnew.exe” pointed on something malicious.
Interesting addition though it checked and found malware in C:\System Volume Information which also can’t be selected in folder check mode.
So please fix this problem ASAP as right now Avast free is incapable to remove Win32:Lethic[Trj] completely.
Using Avast 5 free 5.0.462
100413-1