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BKDR_BREUT.A
Aliases: Trojan:Win32/Meroweq.A (Microsoft)
Malware type: Backdoor
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: No
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It accesses websites to download files. This action allows this malware to possibly add other malware on the affected computer. As of this writing, the said sites are inaccessible.

Technical Details


File size: 69,632 bytes
File type: EXE
Memory resident: No
Initial samples received date: 23 Feb 2012
Payload: Downloads files

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor drops the following copies of itself into the affected system:

  • %User Temp%\Google Cache.exe

(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.)

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}6.{BLOCKED}6.0.28

Dropping Routine

This backdoor drops the following files:

  • %User Startup%\(Empty).lnk - shortcut file pointing to copy of itself

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Download Routine

This backdoor accesses websites to download the following files:

  • http://{BLOCKED}6.{BLOCKED}.0.28/Update/Update.bin
  • http://{BLOCKED}6.{BLOCKED}.0.28/Update/Update2.bin

It saves the files it downloads using the following names:

  • %User Temp%\_%MpsXNpCnns.bin
  • %Current%\_$sbinLop.bin
  • %Current%\_$NosTsh.bin
  • %Current%\Temp.bin

(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.)

As of this writing, the said sites are inaccessible.

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 8.794.05
First VSAPI Pattern Release Date: 23 Feb 2012
VSAPI OPR Pattern Version: 8.795.00
VSAPI OPR Pattern Release Date: 23 Feb 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

Search and delete these files

[ Learn more ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
 
  • %User Temp%\_%MpsXNpCnns.bin
  • %Current%\_$sbinLop.bin
  • %Current%\_$NosTsh.bin
  • %Current%\Temp.bin

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_BREUT.A. 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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Analysis By: Automation
Modified By: Kathleen Notario

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