WORM_VOBFUS.EU


 ALIASES:

Worm:Win32/Vobfus.DF (Microsoft); Ainslot.b (McAfee); W32.IRCBot.NG!gen1 (Symantec); Trojan.MSIL.Pakes.bh (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Dropper.Small.PVH (AVG)

 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:

94,720 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Jun 2013

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.

Installation

This worm drops the following copies of itself into the affected system:

  • %User Profile%\Credentials\wmpnetvk.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It creates the following folders:

  • %User Profile%\Microsoft\Protect
  • %User Profile%\Protect\Credentials

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft® Windows® Operating System = "%User Profile%\Credentials\taskhostt.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MSWUpdate = "%User Profile%\Application Data\lsass.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
MSWUpdate = "%User Profile%\Application Data\lsass.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe %User Profile%\Application Data\lsass.exe"

(Note: The default value data of the said registry entry is Explorer.exe.)

Other System Modifications

This worm deletes the following files:

  • %User Profile%\Application Data\OcQnSgeI

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Micronsoft\addIns

It adds the following registry entries:

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Micronsoft\addIns
Proc = "æxÅ_CHAR(0x19)_ åE"

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Micronsoft\addIns
LOC = "z_CHAR(0x06)_?§?ݡρ¡Ú²"

HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Micronsoft\addIns
FS = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Application Data\lsass.exe = "{random characters}"

Dropping Routine

This worm drops the following files:

  • %User Profile%\Credentials\taskhostt.exe
  • wmpnetvk.exe:ZONE.identifier

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other Details

This worm connects to the following possibly malicious URL:

  • http://www.{BLOCKED}d.com/app/locate_my_ip

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and delete files detected as WORM_VOBFUS.EU using either the Startup Disk or Recovery Console

[ Learn More ]

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\VB and VBA Program Settings\Micronsoft
    • addIns

Step 4

Delete this registry value

[ 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\Run
    • Microsoft® Windows® Operating System = "%User Profile%\Credentials\taskhostt.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • MSWUpdate = "%User Profile%\Application Data\lsass.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • MSWUpdate = "%User Profile%\Application Data\lsass.exe"
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Micronsoft\addIns
    • Proc = "æxÅ_CHAR(0x19)_ åE"
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Micronsoft\addIns
    • LOC = "z_CHAR(0x06)_?§?ݡρ¡Ú²"
  • In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Micronsoft\addIns
    • FS = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %User Profile%\Application Data\lsass.exe = "{random characters}"

Step 5

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe %User Profile%\Application Data\lsass.exe"
      To: Shell = ""Explorer.exe""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %User Profile%\Credentials\taskhostt.exe
  • wmpnetvk.exe:ZONE.identifier

Step 7

Search and delete these folders

[ 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.
  • %User Profile%\Microsoft\Protect
  • %User Profile%\Protect\Credentials

Step 8

Scan your computer with your Trend Micro product to delete files detected as WORM_VOBFUS.EU. 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 9

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.

  • %User Profile%\Application Data\OcQnSgeI


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