Analysis by: Sabrina Lei Sioting
 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: Dropped by other malware, Downloaded from the Internet, Propagates via removable drives

This worm arrives via removable drives. 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 uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It sends gathered information to a predetermined email address using its own Simple Mail Transfer Protocol (SMTP) engine.

  TECHNICAL DETAILS

File Size: 1,615,360 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 03 Oct 2012

Arrival Details

This worm arrives via removable drives.

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:

  • %User Profile%\gupd.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 uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

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
gtalkupdate = "%User Profile%\gupd.exe"

Other System Modifications

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

HKEY_CURRENT_USER\Software\Chilkat Software, Inc.\
ChilkatMail
Key30 = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.\
ChilkatMail
Key30 = "{random characters}"

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

HKEY_CURRENT_USER\Software\Chilkat Software, Inc.

HKEY_CURRENT_USER\Software\Chilkat Software, Inc.\
ChilkatMail

HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.

HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.\
ChilkatMail

Propagation

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

  • essay.exe
  • lecture notes.exe
  • portfolio.exe

Stolen Information

This worm sends gathered information to a predetermined email address using its own Simple Mail Transfer Protocol (SMTP) engine.

Other Details

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

  • http://www.google.com/index.html

NOTES:

Upon execution, it checks for its existence by querying the value of HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\gtalkupdate.

  SOLUTION

Minimum Scan Engine: 9.200

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 terminate files detected as WORM_SILLY.SS

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software
    • Chilkat Software, Inc.
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • Chilkat Software, Inc.

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
    • gtalkupdate = "%User Profile%\gupd.exe"

Step 5

Scan your computer with your Trend Micro product to delete files detected as WORM_SILLY.SS. 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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