WORM_EMOLD.AD

May 10, 2013
 Analysis by: Sabrina Lei Sioting
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • 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:

28,160 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

03 Dec 2009

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:

  • %System%\logon.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
Shell = "Explorer.exe logon.exe"

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

Other System Modifications

This worm deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot

Other Details

This worm connects to the following possibly malicious URL:

  • http://{BLOCKED}rfriends.com/load/get.php?v=1&rs={guid}&n=1&uid=1

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

6.668.04

FIRST VSAPI PATTERN DATE:

03 Dec 2009

VSAPI OPR PATTERN File:

6.669.00

VSAPI OPR PATTERN Date:

04 Dec 2009

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_EMOLD.AD using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

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: Shell = "Explorer.exe logon.exe"
      To: Shell = "Explorer.exe"

Step 4

Scan your computer with your Trend Micro product to delete files detected as WORM_EMOLD.AD. 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.

NOTES:

Restore Safe Boot Registry Settings

To restore safe boot registry settings:

  1. Open a text editor like Notepad.
  2. Copy and paste the following script:
    • On Windows 2000:
    • On Windows Server 2003:
    • On Windows XP:
    • On Windows Vista:
    • On Windows 7:
  3. Save this file as RESTORE.REG.
  4. Execute the file RESTORE.REG.


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