Analysis by: Sabrina Lei Sioting
 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: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 142,336 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 18 Nov 2011

Arrival Details

This Trojan 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 Trojan drops the following non-malicious file:

  • %System%\MSWINSCK.OCX

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
NOHIDORSYS
CheckedValue = "0"

It modifies the following registry entries to hide files with Hidden attributes:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "0"

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • %Windows%\Fonts\services.exe

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

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}.com

However, as of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.300

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

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\Explorer\Advanced\Folder\Hidden\NOHIDORSYS
    • CheckedValue = "0"

Step 3

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\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "0"
      To: CheckedValue = 1

Step 4

Search and delete these components

[ Learn More ]
There may be some components 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. %System%\MSWINSCK.OCX

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_SWISYN.SA. 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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