Analysis by: Sabrina Lei Sioting
 Modified by: Karl Dominguez
 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This backdoor executes the commands from a remote malicious user.

This backdoor steals the information.

This backdoor may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 97,792 bytes
File Type: DLL
Initial Samples Received Date: 18 Apr 2011
Payload: Steals information

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_COMFOO.A

Installation

This backdoor drops the following files:

  • %System%\ms0ert.temp
  • %System%\mstemp.temp

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
ImagePath = "%System%\msobj.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj
DisplayName = "msobj"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\msobj\Security
Security = "{hex values}"

Dropping Routine

This backdoor drops the following file(s), which it uses for its keylogging routine:

  • %System%\ms0ert.temp

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

NOTES:

Backdoor Routine

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

  • Capture Screenshots
  • Log Keystrokes
  • Create/Delete Files and Directories
  • Create/Delete Registry Entries
  • Start/Terminate Processes
It connects to the following URL(s) to send and receive commands from a remote malicious user:
  • www.{BLOCKED}id.dns04.com
  • www.{BLOCKED}holas.dns04.com
  • {BLOCKED}id.dns04.com
  • {BLOCKED}at.yick.lflink.com
  • {BLOCKED}ar.toh.info
  • {BLOCKED}og.gicp.net
As of this writing, the said sites are inaccessible.

Information Theft

This backdoor steals the following information:

  • Operating System version
  • Network Information
  • Physical address
  • Adapter Description
  • Primary Wins Server
  • Secondary Wins Server
  • DNS Servers
  • Gateway
  • IP Mask
  • IP Address
  • HostName
  • User Accounts
  • Drives
  • File System Type
  • Volume Name
  • Free space
  • Used space
  • Total size
  • Disk Types
  • Netbios Information
  • CPU Speed
  • CPU Name
  • CPU Information
  • CPU Vendor Identifier
  • CPU Identifier
  • Display Name
  • Installed Applications
  • System Time
  • System Boot time
  • Internet Explorer BHOs
  • Protocol Information

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.982.03
FIRST VSAPI PATTERN DATE: 18 Apr 2011

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_COMFOO.A

    TROJ_COFMOO.A
    RTKT_COMFOO.A

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Delete this registry key

[ 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
    • msobj

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.
%System%\ms0ert.temp 
%System%\mstemp.temp

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_COMFOO.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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