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WORM_AUTORUN.MCS
Aliases: Worm:Win32/Niojec.gen (Microsoft), Trojan-Downloader.Win32.VB.jdh (Kaspersky), W32.SillyFDC (Symantec), Worm.Win32.Niojec (Ikarus),
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
Encrypted: Yes
In the wild: Yes

Overview


This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

Technical Details


File size: 27,434 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 08 Apr 2011

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It 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:

  • %System%\secpol.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%System%\secpol.exe,"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\xx931
Userinit = "%System%\userinit.exe,%System%\secpol.exe,"

It adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\xx931

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • UFO.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[AutoRun]
open=UFO.exe
Shellexecute=UFO.exe
shell\Auto\command=UFO.exe

Other Details

This worm connects to the following URL(s) to check for an Internet connection:

  • http://www.google.com/

It connects to the following possibly malicious URL:

  • http://{BLOCKED}.com/2005/p/21yjxm.com/1907/jp/logip.php

Solution


Minimum scan engine: 9.200
First VSAPI Pattern File: 7.956.16
First VSAPI Pattern Release Date: 08 Apr 2011
VSAPI OPR Pattern Version: 7.957.00
VSAPI OPR Pattern Release Date: 08 Apr 2011

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_AUTORUN.MCS 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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • xx931

Step 4

Restore this modified 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%System%\secpol.exe,"
      To: Userinit = %System%\userinit.exe,

Step 5

Search and delete AUTORUN.INF files created by WORM_AUTORUN.MCS that contain these strings

[ Learn more ]
[AutoRun]
open=UFO.exe
Shellexecute=UFO.exe
shell\Auto\command=UFO.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.MCS. 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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Analysis By: Automation
Modified By: Sabrina Lei Sioting

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