Analysis by: Christopher Daniel So
ALIASES:

Trojan:Win32/Bamital (Microsoft); Troj/Patched-Y (Sophos)

 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

This backdoor may be dropped by other malware.

  TECHNICAL DETAILS

File Size: 44,793 bytes
File Type: Other
Memory Resident: Yes
Initial Samples Received Date: 12 Mar 2011

Arrival Details

This backdoor may be dropped by other malware.

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
LowRegistry

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
LowRegistry
PFlag = 1

NOTES:

It is loaded by TROJ_BAMITAL.WQ, thus, it is being allowed to execute only when the following processes are running:

  • iexplore.exe
  • opera.exe
  • firefox.exe
  • chrome.exe
  • explorer.exe
  • spoolsv.exe
  • wininit.exe
  • winlogon.exe

Backdoor Routine

This backdoor connects to the following URLs to inform a remote user of its installation:

  • http://{BLOCKED}search.info/update.php?id={random characters}&pr={random number}&fl=ping
  • http://{BLOCKED}rks.co.cc/update.php?id={random characters}&pr={random number}&fl=ping

It then receives the following commands from the command and control server:

  • work - this sends the window information of the process on which this backdoor is running
  • notw - asks the server to send another command

  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_BAMITAL.WQ

    TROJ_BAMITAL.WQ

Step 3

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
    • LowRegistry

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_BAMITAL.WQ. 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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