Trojan-Spy:W32/Small.BSL

Classification

Malware

Trojan-Spy

W32

Trojan-Spy.Win32.Small.bsl, Trojan-Spy:W32/DlRhifrem.A

Summary

Trojan-Spy applications are usually standalone programs that allow malicious individuals to monitor activity on infected computers. Trojan-Spy:Win32.Small.BSL installs a component designed to steal installed certificates.

Removal

Automatic action

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.

Suspect a file is incorrectly detected (a False Positive)?

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

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    Note You need administrative rights to change the settings.

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Technical Details

Creates the following registry entries:

  • HKEY_CLASSES_ROOT\CLSID\{BD942DA7-96C8-4342-84C6-E2BCFE69FE11}\InprocServer32 (Default) = "C:\WINDOWS\system32\acrobat.dll" ThreadingModel = "Apartment" (Using the name, Adobe Acrobat ActiveX Control)
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Explorer\Browser Helper Objects\{BD942DA7-96C8-4342-84C6-E2BCFE69FE11} NoExplorer = 0x00000001 (1)
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run Adobe Acrobat ActiveX Control = "Rundll32 acrobat.dll,AInit"

It attempts to create the following registry entry:

  • HKEY_LOCAL_MACHINE\Software\Acrobat\ "1" = "124.217.251.118" "2" = 0x00000050 (80) "3" = /NNN/parse.php

It then drops a file into the following folder:

  • %windir%\system32\

The dropped file is called acrobat.dll and is 51712 bytes in size.The malware sets acrobat.dll with a hidden file attribute and changes its date properties to the current system time.Small.BSL then displays the following fake/decoy dialog message:

When the dialog box is closed the malware will search for and terminate all running Internet Explorer processes. After this, it will launch Internet Explorer as a hidden process which has the malicious component attached.This malicious component acts like a Browser Helper Object (BHO).After the user has started Internet Explorer the malware will attempt to communicate with a server located at the following URL:

  • http://124.217.[REMOVED]/NNN/parse.php

The BHO has the following functionality:

  • Steals installed certificates
  • Deletes user cookie files
  • Updates itself
  • Deletes files from C:\Documents and Settings \%username%\Application Data\Macromedia\Flash Player\
  • Updates registry information