Threat Descriptions

Trojan-Spy:W32/Goldun.CW

Classification

Category :

Malware

Type :

Trojan-Spy

Platform :

W32

Aliases :

Trojan-Spy:W32/Goldun.CW

Summary

This type of trojan secretly installs spy programs and/or keylogger programs.

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Trojan-Spy:W32/Goldun.CW silently downloads and installs a file on the infected system. The downloaded file in turn downloads and executes another file which is most likely malware.

Arrival

Goldun.CW is distributed as an FSG packed EXE file. It creates and opens the following Bitmap file to hide its original intent:

Note: This image is saved in the default Temporary folder as screen.bmp.

Execution

Goldun.CW drops the following UPX-compressed DLL file on Windows System folder:

  • %systemdir%\mscods.dll

Note: %systemdir% by default is C:\Windows\system32.The DLL will connect, download, and execute a file from the following URL:

  • http://everythingdiscounted.biz/store/images/extras/[...].jpg

The code containing the above URL is encrypted using a simple XOR routine.The executed file drops a file named vbrs.bat into the default Temporary folder. The BAT file deletes the EXE file and the BAT file itself, effectively removing all traces of the malware on the system.

Registry

The DLL file is installed as a Browser Helper Object (BHO) so that when ever an Internet Explorer session is started, the DLL will also execute. It does this by creating the following Registry keys:

  • [HKCR\CLSID\{45357971-2534-8760-3685-423479197575}]
  • [HKLM\SOFTWARE\Classes\CLSID\{45357971-2534-8760-3685-423479197575}]