PE_SQUIRREL.A


 ALIASES:

Virus:Win32/Squirrel.A (Microsoft); W32/Squirrel (McAfee); W32.Squirrel (Symantec); Virus.Win32.Squirrel.a (Kaspersky); BehavesLike.Win32.Malware.sfm (mx-v) (Sunbelt); Win32/Squirrel.A (AVG)

 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:

245,760 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 May 2013

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.

Autostart Technique

This file infector registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\DBGV

Other System Modifications

This file infector adds the following registry keys:

HKEY_CURRENT_USER\Software\Sysinternals\
DbgView

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DBGV
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DBGV
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DBGV
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DBGV
ImagePath = "\??\%System Root%\Dbgv.sys"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\DBGV
ImagePath = "\??\%System%\Drivers\Dbgv.sys"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Systems Internals\
DbgView

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Dbgv\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Dbgv\Security

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\Dbgv

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\DBGV\Enum

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\DBGV\Security

Dropping Routine

This file infector drops the following files:

  • %System%\Drivers\Dbgv.sys

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

This report is generated via an automated analysis system.

  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

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.

  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • DBGV
  • In HKEY_CURRENT_USER\Software\Sysinternals
    • DbgView

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\ControlSet001\Services\DBGV
    • Type = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\DBGV
    • ErrorControl = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\DBGV
    • Start = "3"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\DBGV
    • ImagePath = "\??\%System Root%\Dbgv.sys"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\DBGV
    • ImagePath = "\??\%System%\Drivers\Dbgv.sys"

Step 5

Search and delete this file

[ Learn More ]
There may be some 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\Dbgv.sys

Step 6

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

Step 7

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Systems Internals
    • DbgView
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dbgv
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Dbgv
    • Security
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services
    • Dbgv
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DBGV
    • Enum
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\DBGV
    • Security


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