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WORM_STEKCT.EVL
Aliases: Trojan.Win32.Generic!BT (Sunbelt)
Malware type: Worm
Destructive: No
Platform: Windows 2000, Windows XP, Windows Server 2003
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet, Propagates via instant messaging applications, Propagates via social networking sites

It uses several instant messaging applications and a social networking site to spread. The instant message it sends is a link that downloads a copy of itself.

It terminates processes or services that are mostly related to anti-malware programs. It also deletes the files that are related to the processes or services it terminates. It does the said routine to keep itself running on the affected system.

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.

It connects to a website to send and receive information.

Technical Details


File size: 93,184 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 10 May 2012
Payload: Connects to URLs/IPs, Terminates processes, Deletes files

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.

It may be downloaded from the following remote sites:

  • http://bit.ly/K8sluf?{random}

Installation

This worm drops the following copies of itself into the affected system:

  • %Windows%\iqs.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

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
Microsoft Firevall Engine = "%Windows%\iqs.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Firevall Engine = "%Windows%\iqs.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Terminal Server\
Install\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Firevall Engine = "%Windows%\iqs.exe"

Other System Modifications

This worm adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\iqs.exe = "%Windows%\iqs.exe:*:Enabled:Microsoft Firevall Engine"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Windows%\iqs.exe = "%Windows%\iqs.exe:*:Enabled:MSN Messenger"

Propagation

This worm sends the following messages via instant-messaging (IM) applications:

http://bit.ly/K8sluf?{random} - also detected as WORM_STEKCT.EVL

It targets the following social networking site(s):

  • Facebook

It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:

  • AIM
  • Google Talk
  • ICQ
  • MSN
  • Yahoo! Messenger

Backdoor Routine

This worm connects to the following websites to send and receive information:

  • {BLOCKED}.{BLOCKED}.228.202
  • news.{BLOCKED}dio.net
  • safe.{BLOCKED}dio.net

Process Termination

This worm terminates processes or services that contain any of the following strings if found running in the affected system's memory:

  • AntiVirService
  • AviraUpgradeService
  • MSASCui.exe
  • MsMpEng.exe
  • MsMpSvc
  • WinDefend
  • YahooAUService
  • YahooAUService.exe
  • avgnt.exe
  • avp
  • avp.exe
  • egui.exe
  • ekrn
  • ekrn.exe
  • kavsvc.exe
  • msseces.exe
  • wuauserv

NOTES:

This worm deletes the files related to the terminated running processes.

Solution


Minimum scan engine: 9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn more ]

Step 3

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
    • Microsoft Firevall Engine = "%Windows%\iqs.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Firevall Engine = "%Windows%\iqs.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Terminal Server\Install\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Firevall Engine = "%Windows%\iqs.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\iqs.exe = "%Windows%\iqs.exe:*:Enabled:Microsoft Firevall Engine"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\iqs.exe = "%Windows%\iqs.exe:*:Enabled:MSN Messenger"

Step 4

Search and delete this file

[ Learn more ]
There may be some component files that are 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.
  • %Windows%\iqs.exe

Step 5

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

Step 6

Restore files from backup Only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on your computer again.


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Analysis By: Automation
Modified By: Cris Nowell Pantanilla

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