WORM_BUTILEG.B


 ALIASES:

TrojanDownloader:Win32/Injector.gen!W (Microsoft); W32/Generic.acg!worm !! (McAfee); W32.Fubalca.D (Symantec); PAK:PE_Patch, PAK:UPack, Worm.Win32.Butileg.b (Kaspersky); Trojan.Win32.Packer.Upack0.3.9 (ep) (Sunbelt); Win32.Worm.Butileg.D (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

6,436 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

20 Jan 2012

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Other System Modifications

This worm deletes the following files:

  • %Windows%\debug.txt

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

Dropping Routine

This worm drops the following files:

  • %Program Files%\Common Files\Microsoft Shared\Web Folders\MSOSV.EXE
  • %Windows%\svchost.exe

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

Other Details

This worm connects to the following possibly malicious URL:

  • http://temp.{BLOCKED}8.com/table.gif

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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.
  • %Program Files%\Common Files\Microsoft Shared\Web Folders\MSOSV.EXE
  • %Windows%\svchost.exe

Step 3

Scan your computer with your Trend Micro product to delete files detected as WORM_BUTILEG.B. 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 4

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. %Windows%\debug.txt


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