Analysis by: Erika Bianca Mendoza
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

This backdoor may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 161792 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 Mar 2011
Payload: Connects to URLs/Ips, Downloads files, Drops files

Arrival Details

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This backdoor drops the following files:

  • %Application Data%\A1B2.580

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

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

  • %Application Data%\Microsoft\conhost.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
conhost = %Application Data%\Microsoft\conhost.exe

Download Routine

This backdoor connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}icarchive.com/blog/images/3521.jpg?v83=32&tq=gKZEtzyMv5rJqxG1J42pzMffBvIu3ejbwvgS917X65rJqlLfgPiWW1cg

It saves the files it downloads using the following names:

  • %UserTemp%\csrss.exe - detected by Trend Micro as BKDR_CYCBOT.EM

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}ftwaredevelopment.com/WindowsLiveWriter/web-2_0_thumb_1.gif?v0=79&tq=gKZEtzy%2FcaWs3hvQ94zoLSYjeLZez7%2BSsKdM2GhepyKVvh1qpEe9OBj%2BVFLuWaGGs821dovQ937GPqiSuGo0riWh4%2B%2B6FW57o3z1CSq%2BgPymfj9uUlZ1qd6zNf6pHXeYpkbytqYOZi2fn1OniK5oTcWcdPHlmE9H3r2VmYDpyZPYuIdmicR1uEyEw3uWoFfvazMG0Fz4xcF69CzRaEoFCAWTO%2B2iWEK4akmugZuhfShrcOXRTpG%2BY2Lx%2BNoy4mJK%2BnLzz7%2BOEkqUTSRPV00K4OYGJMKuWWhNPkD%2FyUrlo6pdq3qynN5PqxG64im%2B36cpWCX4oL
  • http://{BLOCKED}seklick.com/blog/images/3521.jpg?v64=53&tq=gKZEtzyMv5rJqxG1J42pzMffBvIu3ejbwvgS917W65rJqlLfgPiWW1cg

  SOLUTION

Minimum Scan Engine: 8.900

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_GBOT.BE

    BKDR_CYCBOT.EM

Step 3

Terminate a process file/s detected as BKDR_GBOT.BE

[ Learn More ]

*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.

Step 4

Delete this 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\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • conhost = %Application Data%\Microsoft\conhost.exe

Step 5

Search and delete this file

[ 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. %Application Data%\A1B2.580

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_GBOT.BE. 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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