Threat Encyclopedia

WORM_STTKR.A

Publish date: March 30, 2013

ANALYSIS BY

Rika Joi Gregorio


ALIASES:

Trojan:Win32/AgentBypass.gen!G(Microsoft), W32/CodeCcl-based!Maximus(Authentium), Trojan.Win32.Spy(Ikarus)

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:

  • In the wild: Yes

OVERVIEW


This worm arrives as a component bundled with malware/grayware packages.

It modifies registry entries to disable the Windows Firewall settings. This action allows this malware to perform its routines without being deteted by the Windows Firewall.

TECHNICAL DETAILS

File Size:

100,731 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

26 Mar 2013

Arrival Details

This worm arrives as a component bundled with malware/grayware packages.

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost\
netsvcs

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\VaSecurity

It modifies the following registry entries to disable the Windows Firewall settings:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = 1

(Note: The default value data of the said registry entry is 0.)

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{port number 1}:TCP = "{port number 1}:TCP:*:Enabled:@xpsp2res.dll,-22002"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{port number 2}:UDP = "{port number 2}:UDP:*:Enabled:@xpsp2res.dll,-22002"

Download Routine

This worm connects to the following URL(s) to download its component file(s):

  • http://www.{BLOCKED}a.com/images/newinfo.txt

Other Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.83.115:35105

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

9.818.05

FIRST VSAPI PATTERN DATE:

26 Mar 2013

VSAPI OPR PATTERN File:

9.819.00

VSAPI OPR PATTERN Date:

27 Mar 2013

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

Restart in Safe Mode

[ Learn More ]

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.


 
  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost\netsvcs
  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VaSecurity

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {port number 1}:TCP = "{port number 1}:TCP:*:Enabled:@xpsp2res.dll,-22002"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {port number 2}:UDP = "{port number 2}:UDP:*:Enabled:@xpsp2res.dll,-22002"

Step 5

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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
    • From: EnableFirewall = 1
      To: EnableFirewall = 0

Step 6

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