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BKDR_BAMITAL.SMZ

October 08, 2012
 Analysis by: Christopher Daniel So
 ALIASES:

Troj/Patched-Y (Sophos), Trojan.Win32.Bamital.ce (Sunbelt)

 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.

It connects to certain URLs. It may do this to remotely inform a malicious user of its installation. It may also do this to download possibly malicious files onto the computer, which puts the computer at a greater risk of infection by other threats.

  TECHNICAL DETAILS

File Size:

35,116 bytes

File Type:

Other

Memory Resident:

Yes

Initial Samples Received Date:

25 Jan 2011

Arrival Details

This backdoor may be dropped by the following malware:

  • TROJ_BAMITAL.QUE

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
Run = 0

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
LowRegistry
Uses32 = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
LowRegistry
TimeGetWork = 14a89

Download Routine

This backdoor connects to the following malicious URLs:

  • http://{random MD5 value}.info/message.php?subid=464&br={random string}&os=12&flg=3&id={random string}&ad=&ver=_if18

Other Details

This backdoor does the following:

  • It only executes when running in the following processes:
    • iexplore.exe
    • opera.exe
    • firefox.exe
    • chrome.exe
    • explorer.exe
    • spoolsv.exe
    • wininit.exe
    • winlogon.exe

  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

Scan your computer with your Trend Micro product and note files detected as BKDR_BAMITAL.SMZ

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete the file detected as BKDR_BAMITAL.SMZ

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

Step 5

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 6

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