Threat Description

Trojan-Spy:​W32/Small.BSL

Details

Aliases:Trojan-Spy.Win32.Small.bsl, Trojan-Spy:​W32/DlRhifrem.A
Category:Malware
Type:Trojan-Spy
Platform:W32

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

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

You may wish to refer to the Support Community for further assistance. You also may also refer to General Removal Instructions for a general guide on alternative disinfection actions.



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





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