ALIASES:

Virus:Win32/Snow.A (Microsoft); W32/Snow.a (McAfee); W32.Snow.A (Symantec); Trojan-Dropper.Win32.Agent.ajy (Kaspersky); Trojan.Generic.7392555 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:

  • Threat Type: File infector

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

  TECHNICAL DETAILS

File Size: 733,184 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 25 Apr 2012

Arrival Details

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

Other System Modifications

This file infector adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
A = "%Program Files%\VMware\VMware Tools\vmacthlp.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
B = "%Program Files%\Messenger\msmsgs.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
C = "{malware path and file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
D = "%Program Files%\VMware\VMware Tools\vmtoolsd.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
E = "%Program Files%\VMware\VMware Tools\VMUpgradeHelper.exe"

Dropping Routine

This file infector drops the following files:

  • %System%\drivers\npf.sys
  • %Windows%\pthreadvc.dll
  • %Windows%\packet.dll
  • %Windows%\wpcap.dll
  • %Windows%\CTFMON.EXE

(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.)

This report is generated via an automated analysis system.

  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

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • SNOW

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\SNOW
    • A = "%Program Files%\VMware\VMware Tools\vmacthlp.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
    • B = "%Program Files%\Messenger\msmsgs.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
    • C = "{malware path and file name}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
    • D = "%Program Files%\VMware\VMware Tools\vmtoolsd.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SNOW
    • E = "%Program Files%\VMware\VMware Tools\VMUpgradeHelper.exe"

Step 4

Search and delete these files

[ 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.
  • %System%\drivers\npf.sys
  • %Windows%\pthreadvc.dll
  • %Windows%\packet.dll
  • %Windows%\wpcap.dll
  • %Windows%\CTFMON.EXE

Step 5

Scan your computer with your Trend Micro product to clean files detected as PE_SNOW.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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