Analysis by: Jennifer Gumban
 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:
 INFORMATION EXPOSURE:

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 modifies the Internet Explorer Zone Settings.

  TECHNICAL DETAILS

File Size: 339,968 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 30 Dec 2013

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.

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
{random value} = "%All Users Profile%\System.exe" .."

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random value} = "%All Users Profile%\System.exe" .."

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER\Environment
SEE_MASK_NOZONECHECKS = "1"

HKEY_CURRENT_USER\Software\{random value}
US = "@"

Web Browser Home Page and Search Page Modification

This worm modifies the Internet Explorer Zone Settings.

NOTES:

It drops the following copies of itself in the following affected system:

  • %Program Files%\System.exe
  • %All Users Profile%\System.exe.tmp
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\{random value}.exe
  • %System%\! My Picutre.SCR
  • %Drive Letter%\! My Picutre.SCR

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 10.506.02
FIRST VSAPI PATTERN DATE: 30 Dec 2013
VSAPI OPR PATTERN File: 10.507.00
VSAPI OPR PATTERN Date: 31 Dec 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

Scan your computer with your Trend Micro product and note files detected as WORM_PCUT.JSC

Step 3

Restart in Safe Mode

[ Learn More ]

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
    • {random value} = "%All Users Profile%\System.exe" .."
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • {random value} = "%All Users Profile%\System.exe" .."
  • In HKEY_CURRENT_USER\Environment
    • SEE_MASK_NOZONECHECKS = "1"
  • In HKEY_CURRENT_USER\Software\{random value}
    • US = "@"

Step 5

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