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F-Secure Malware Information Pages: Small.QP

[Summary] | [Detailed Description]

Name : Small.QP
Alias:Trojan-Dropper.Win32.Small.qp, Trojan-Dropper:W32/Small.qp
Type:Trojan-Dropper
Category:Malware
Radar

Summary
Small.QP copies itself to the Windows folder and attempts to download and install other malware to the system.
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Detailed Description
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:

  • http://www.max-stats.com/l/[REMOVED].php?i=21
    Data downloaded is saved in the file, %windir%\prefoct.dat
  • http://www.teen4-sex.com/[REMOVED].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.
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F-Secure Corporation

Last Modified: January 31, 2007