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TrojanDownloader:Win32/Bulilit.A


TrojanDownloader:Win32/Bulilit.A is a trojan that silently downloads and installs other programs without consent. This could include the installation of additional malware or malware components to an affected computer.


What to do now

To detect and remove this threat and other malicious software that may have been installed in your computer, run a full-system scan with an up-to-date antivirus product such as the following: For more information about using antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.

Threat behavior

TrojanDownloader:Win32/Bulilit.A is a trojan that silently downloads and installs other programs without consent. This could include the installation of additional malware or malware components to an affected computer.
Installation
TrojanDownloader:Win32/Bulilit.A creates the following files on an affected computer:

  • <system folder>\dx5.exe - detected as TrojanDownloader:Win32/Bulilit.A
  • <system folder>\xvhost.sb
  • c:\rec.bat
  • c:\documents and settings\administrator\local settings\temp\svchost.exe - detected as Trojan:Win32/Killav.FA
  • c:\documents and settings\administrator\local settings\temp\is-46adc.tmp\is-tbi1h.tmp
  • c:\documents and settings\administrator\local settings\temp\is-dno7u.tmp\_iscrypt.dll
  • c:\documents and settings\administrator\local settings\temp\is-dno7u.tmp\_isetup\_shfoldr.dll

 
Note: <system folder> refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:\Winnt\System32; and for XP, Vista, and 7 is C:\Windows\System32.

The malware modifies the following registry entries to ensure <system folder>\dx5.exe executes at each Windows start:

In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Adds value: "RunmeAtStartup"
With data: "c:\windows\system32\dx5.exe"
Payload
Contacts remote host
TrojanDownloader:Win32/Bulilit.A may contact a remote host at a8d61.3bc6ad2ed.com using port 90. Commonly, malware may contact a remote host for the following purposes:
  • To report a new infection to its author
  • To receive configuration or other data
  • To download and execute arbitrary files (including updates or additional malware)
  • To receive instruction from a remote attacker
  • To upload data taken from the affected computer

This malware description was produced and published using our automated analysis system's examination of file SHA1 5579b1f2e874f0dd6cf49d6e94fc2cbf03d26bd0.

Symptoms

System changes
The following system changes may indicate the presence of this malware:

  • The presence of the following files:
  • <system folder>\dx5.exe
    <system folder>\xvhost.sb
    c:\rec.bat
    c:\documents and settings\administrator\local settings\temp\svchost.exe
    c:\documents and settings\administrator\local settings\temp\is-46adc.tmp\is-tbi1h.tmp
    c:\documents and settings\administrator\local settings\temp\is-dno7u.tmp\_iscrypt.dll
    c:\documents and settings\administrator\local settings\temp\is-dno7u.tmp\_isetup\_shfoldr.dll

     
  • The presence of the following registry modifications:
    In subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  • Adds value: "RunmeAtStartup"
    With data: "c:\windows\system32\dx5.exe"

     

Prevention


Alert level: Severe
First detected by definition: 1.85.1270.0
Latest detected by definition: 1.175.904.0 and higher
First detected on: Jul 02, 2010
This entry was first published on: Oct 27, 2010
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • Trojan.Win32.Swisyn.aiub (Kaspersky)