WORM_SILLY.RK

Malware type: Worm

Aliases: No Alias Found

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 98, ME, NT, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

Low

Distribution potential:

Medium

Infection Channel 1 : Propagates via removable drives


Description: 

A worm is a malware that is designed to propagate and spread across networks. Worms are known to propagate using one or several of different transmission vectors like email, IRC, network shares, instant messengers (IM), and peer-to-peer (P2P) networks.

Worms do not infect files, but may carry one or more payloads, such as computer security compromise and information theft.

Worms typically modify system settings to automatically start. Users may need to terminate worms before they can be deleted. Also, restoring affected systems may require procedures other than scanning with an antivirus program.

For additional information about this threat, see:

Description created: Oct. 21, 2009 8:49:11 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: Varies

Initial samples received on: Oct 21, 2009

Details:

Installation

This worm drops the following copies of itself:

  • %System%\BttnServ.exe
  • %System%\dllcache\dllcache.exe
  • %System%\system32.exe
  • %Windows%\winst.log

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

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

HKEY_CLASSES_ROOT\CLSID\{DATEMSIT-0102-6066-1980-KEO012306603}

Autostart Techniques

This worm creates the following registry entry to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
system32 = "%System%\system32.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Run
(Default) = "%Windows%\svchost.exe"
CPQEASYBTTN = "%System%\BttnServ.exe"
dllcache = "%System%\dllcache\dllcache.exe"

Propagation via Removable

This worm drops copies of itself in all removable drives.

Other Details

This worm uses the following file name for its dropped files to trick users into thinking that it is a legitimate application:

  • New Folder.exe

It bears the icon of files related to the following application:

  • Microsoft Word

Analysis By: Michael Cabel

Revision History:

First pattern file version: 7.779.00
First pattern file release date: Jan 19, 2011

SOLUTION


Minimum scan engine version needed: 8.900

Pattern file needed: 7.779.00

Pattern release date: Jan 19, 2011


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

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 1: Identify and terminate files detected as WORM_SILLY.RK  [learn how]

*Note:

  1. For Windows 98 and ME users, 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 2:  Delete this registry value  [learn how]

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
    • system32 = "%System%\system32.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
    Windows\CurrentVersion\Run
    • (Default) = "%Windows%\svchost.exe"
    • CPQEASYBTTN = "%System%\BttnServ.exe"
    • dllcache = "%System%\dllcache\dllcache.exe"

 Step 3:  Delete this registry key  [learn how]

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_CLASSES_ROOT\CLSID
    • {DATEMSIT-0102-6066-1980-KEO012306603}

 Step 4: Scan your computer with your Trend Micro product to delete files detected as WORM_SILLY.RK  

*Note: 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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