Windows 7 Home Premium
it's a couple of weeks I'm getting crazy with some infection that took place in my laptop.
In most cases, few minutes after starting the nb, Avira detects an infected file; here's an example of the avira log after detection (hope the italian does not provoke confusion!):
Inizia con la scansione di 'C:\ProgramData\Microsoft\Security\Client\temp\tmpD4FA.exe'
[RILEVAMENTO] Si tratta del cavallo di Troia TR/Crypt.ZPACK.Gen
[NOTA] Il file è stato spostato in quarantena con il nome '50976da2.qua'!
The infected filename changes every time, but is always located in the same folder and has always the same structure tmxXXX.exe
After investigation, I suspect that the infected file is created by SecurityHelper.dll, that is located in the folder C:\ProgramData\Microsoft\Security\Client\ (there's also another similar file SecurityProvider.dll in the same folder).
I checked with Unlocker that both files SecurityHelper.dll and SecurityProvider.dll are controlled by the proces explorer.exe! I also tried to force the both file's deletion (which blocks explorer.exe), but they're created again at restart.
Another strange thing is that it seems that the malicious effects of the infection become visible always at the same time in the day, when a windows appears asking for permission to execute an operation (if you click No, the windows appears again), and multiple unknown instances of the same process appear ion the Task Manager (e.g. charmap.exe).
Normally, executing combobox.exe solves the infection for one session, but it appears again at the next reboot.
Need for help, this is really making me crazy!