TROJ_BAMITAL.SMW

 Analysis by: Roland Marco Dela Paz

 ALIASES:

W32/Bamital.e (McAfee); TrojanDropper:Win32/Bamital.C (Microsoft)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan modifies files, disabling programs and applications from properly running. It deletes registry entries, causing some applications and programs to not function properly.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

30 Nov 2010

Installation

This Trojan drops the following files:

  • %Temp%\explorer.dat
  • %Temp%\winlogon.dat
  • %System Root%\Documents and Settings\All Users\Documents\Server\hlp.dat
  • %System Root%\Documents and Settings\All Users\Documents\Server\admin.txt

(Note: %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp or C:\WINNT\Temp.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\Documents and Settings\All Users\Documents\Server

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other System Modifications

This Trojan modifies the following files:

  • %Windows%\explorer.exe
  • %System%\winlogon.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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.)

It deletes the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "0"

Other Details

This Trojan deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.663.00

VSAPI OPR PATTERN Date:

30 Nov 2010

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

Identify and delete files detected as TROJ_BAMITAL.SMW using the Recovery Console

[ Learn More ]

Step 3

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.
  • %Temp%\explorer.dat
  • %Temp%\winlogon.dat

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System Root%\Documents and Settings\All Users\Documents\Server

Step 5

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

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %System%\winlogon.exe
  • %Windows%\explorer.exe

Step 7

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
    Windows NT\CurrentVersion\SystemRestore
    DisableSR = 0

NOTES:
Note that for Step 6, the same procedure can be done to restore files, registry entries, and registry keys.


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