Analysis by: Roland Dela Paz
ALIASES:

Sophos: W32/CpLink-I; Kaspersky: Trojan-Spy.Win32.Webmoner.atv

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Copies itself in all available physical drives, Propagates via removable drives, Propagates via shared drives

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

It adds registry entries to enable its automatic execution at every system startup.

  TECHNICAL DETAILS

File Size: 26,112 bytes
File Type: PE
Memory Resident: Yes
Initial Samples Received Date: 02 Dec 2010
Payload: Drops files

Arrival Details

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

It may arrive via network shares.

Installation

This worm drops the following files:

  • %System Root%\Documents and Settings\All Users\Start Menu\Internet Explorer.lnk - autostart component detected as EXPL_CPLNK.SM
  • %Common Startup%\Microsoft Update.lnk - autostart component detected as EXPL_CPLNK.SM
  • %Favorites%\Microsoft Update.lnk - autostart component detected as EXPL_CPLNK.SM

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Common Startup% is the system's shared Startup folder, which is usually C:\Windows\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\All Users\Programs\Startup on Windows NT, and C:\Documents and Settings\All Users\Start Menu\Programs\Startup on Windows 2000, XP, and Server 2003.. %Favorites% is the current user's Favorites folder, which is usually C:\Windows\Favorites on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Favorites on Windows NT, and C:\Documents and Settings\{user name}\Favorites on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Recycler = "%System Root%\RECYCLER.lnk"

Propagation

This worm drops the following copies of itself in all physical and removable drives:

  • mso.sys

NOTES:

As part of its propagation routine, it also drops a copy of itself as MSO.SYS in all shared folders. In addition, it drops the file RECYCLER.LNK file to automatically execute copies of itself when a user accesses the drives of an affected system.

It then drops the following shortcut files, all of which are detected as EXPL_CPLNK.SM, in removable drives and shared folders:

  • Documents and Settings.lnk
  • Program Files.lnk
  • System Volume Information.lnk
  • WINDOWS.lnk

The said shortcut files are used to enable automatic execution of dropped copies in removable drives and shared folders.

  SOLUTION

Minimum Scan Engine: 8.900
FIRST VSAPI PATTERN FILE: 7.670.07
FIRST VSAPI PATTERN DATE: 02 Dec 2010
VSAPI OPR PATTERN File: 7.671.00
VSAPI OPR PATTERN Date: 02 Dec 2010

Step 1

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Remove malware files dropped/downloaded by WORM_WEBMONER.JC

Step 3

Scan your computer with your Trend Micro product and note files detected as WORM_WEBMONER.JC

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Recycler = "%System Root%\RECYCLER.lnk"

Step 6

Search and delete files detected as WORM_WEBMONER.JC Some component files may be 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.

To manually delete malware/grayware files from the affected system:

• For Windows 2000, Windows XP, and Windows Server 2003 users:

  1. Right-click Start then choose Search....
  2. In the Named input box, type the name of the file that was detected earlier.
  3. In the Look In drop-down list, select My Computer then press Enter.
  4. Once located, select the file then press SHIFT+DELETE to delete it.
  5. Repeat steps 2-4 for the remaining files.

• For Windows Vista and Windows 7 users:

  1. Click Start>Computer.
  2. In the Search input box, type the name of the file that was detected earlier.
  3. Once located, select the file then press SHIFT+DELETE to delete it.
  4. Repeat steps 2 and 3 for the remaining files.

Step 7

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