Upon execution, this malware creates the mutex _Win_Loader_
to ensure that only one instance of itself is running in memory.
Additionally, it drops the following files in the affected system:
- %windir%\winlogon32.exe - A copy of itself (Detected as Trojan-Dropper.Win32.Small.qp)
- %windir%\winlogon32.dll - Another malware file (Detected as Trojan-Downloader.Win32.Small.anj)
- %windir%\prefoct.dat - An empty file
As a stealth mechanism, it loads the dropped DLL, winlogon32.dll, under the legitimate process: lsass.exe.
Trojan-Downloader.Win32.Small.anj, on the other hand, creates the mutex _Win_Loader__Win_Loader_.
This malware attempts to connect to the following web sites to possibly download other malicious components:
Data downloaded is saved in the file, %windir%\prefoct.dat
Data downloaded is saved in the file, %wndir%\_tmp0232.exe
Small.QP then executes the downloaded file, _tmp0232.exe.
Note: Both download sites are unavailable at the time of writing.
There are additional details on Small.QP on F-Secure's Weblog