Threat Encyclopedia

BKDR_VISEL.FO

Publish date: October 09, 2012

ANALYSIS BY

Roland Marco Dela Paz


ALIASES:

Trojan:Win32/Strigy.A (Microsoft); ackdoor.Loknod (Symantec)

PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

OVERALL RISK RATING:
DAMAGE POTENTIAL:
DISTRIBUTION POTENTIAL:
REPORTED INFECTION:

  • Threat Type:Backdoor

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Dropped by other malware


This backdoor may be dropped by other malware.

It executes commands from a remote malicious user, effectively compromising the affected system. It connects to a website to send and receive information.

It retrieves specific information from the affected system.

TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

25 Apr 2012

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_MDROP.ZD

Installation

This backdoor adds the following folders:

  • c:\a

It drops the following component file(s):

  • %User Temp%\print32.dll - also detected as BKDR_VISEL.FO
  • %Program Files%\Common Files\odbc.nls - also detected as BKDR_VISEL.FO

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

It drops the following copies of itself into the affected system:

  • %Windows%\Temp\s{random numbers}.dat

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Its DLL component is injected to the following process(es):

  • spoolsv.exe

Other System Modifications

This backdoor deletes the following files:

  • %Program Files%\Common Files\odbc_dmc.nls
  • %Program Files%\Common Files\odbc_orp.nls
  • %Program Files%\Common Files\odbc_res.nls
  • %Program Files%\Common Files\odbc_lif.nls
  • %Program Files%\Common Files\odbc_ger.nls
  • %Program Files%\Common Files\odbc_rcs.nls
  • %Program Files%\Common Files\odbc_div.nls
  • %Program Files%\Common Files\odbc_dua.nls
  • %Program Files%\Common Files\odbc_rehto.nls
  • %Program Files%\Common Files\dumpodbc.exe
  • %Program Files%\Common Files\odbc_txe.nls
  • %Program Files%\Common Files\odbc_gpj.nls
  • %Program Files%\Common Files\odbc_yek.nls

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Spooler
FailureActions = {HEX values}

(Note: The default value data of the said registry entry is {default value}.)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Change the port it uses when connecting to its C&C server
  • Check contents of %Program Files%\Common Files folder
  • Connect to a new C&C IP address
  • Connect to a website via HTTP
  • Create/Manipulate threads
  • Download and execute files
  • Load/free libraries
  • Log user keystrokes

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It connects to the following websites to send and receive information:

  • {BLOCKED}.{BLOCKED}.9.132

Process Termination

This backdoor terminates the following services if found on the affected system:

  • spooler
  • stisvc
  • wuauserv
  • Norton Internet Security
  • Norton 360
  • Norton AntiVirus

Information Theft

This backdoor retrieves the following information from the affected system:

  • Computer name
  • IP address
  • Operating system information

Stolen Information

This backdoor saves the stolen information in the following file:

  • c:\a\b.txt

SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.942.04

FIRST VSAPI PATTERN DATE:

25 Apr 2012

VSAPI OPR PATTERN File:

8.943.00

VSAPI OPR PATTERN Date:

25 Apr 2012

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by BKDR_VISEL.FO

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Spooler
    • From: FailureActions = {HEX values}
      To: FailureActions = {Default values}

Step 5

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
c:\a

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_VISEL.FO. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

%Program Files%\Common Files\odbc_dmc.nls
%Program Files%\Common Files\odbc_orp.nls
%Program Files%\Common Files\odbc_res.nls
%Program Files%\Common Files\odbc_lif.nls
%Program Files%\Common Files\odbc_ger.nls
%Program Files%\Common Files\odbc_rcs.nls
%Program Files%\Common Files\odbc_div.nls
%Program Files%\Common Files\odbc_dua.nls
%Program Files%\Common Files\odbc_rehto.nls
%Program Files%\Common Files\dumpodbc.exe
%Program Files%\Common Files\odbc_txe.nls
%Program Files%\Common Files\odbc_gpj.nls
%Program Files%\Common Files\odbc_yek.nls

Step 8

Scan your computer with your Trend Micro product to delete files detected as BKDR_VISEL.FO. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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