Analysis by: Kathleen Notario
 PLATFORM:

Windows 2000, XP, Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: Varies
File Type: Other
Memory Resident: Yes
Initial Samples Received Date: 27 Aug 2010
Payload: Drops files

Installation

This Trojan adds the following folders:

  • %Windows%\PCHEALTH\AutoClean

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

It adds the following processes:

  • explorer.exe

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
AutoProtect = %Windows%\pchealth\AutoClean\AutoProtect.vbs

Propagation

The said .INF file contains the following strings:

[autorun]
icon=%SystemRoot%\system32\SHELL32.dll,7
open=AutoClean\shh.bat
action=Virus Protection by Scarecrow(The Mick)
shell\open\command=AutoClean\shh.bat

Dropping Routine

This Trojan drops the following files:

  • %Windows%\pchealth\AutoClean\AutoProtect.vbs - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\autorun.inf - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\call.bat - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\ComboKill.bat - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\invis.vbs - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\Replicate.vbs - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\shh.bat - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\Patch\PatchIt.bat - also detected as TROJ_SCARECROW.A
  • %Windows%\pchealth\AutoClean\Patch\update003.bat - also detected as TROJ_SCARECROW.A

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

It sets the attributes of its dropped file(s) to the following:

  • Read-Only, Hidden, and System

Other Details

Based on analysis of the codes, it has the following capabilities:

  • Drops the following files in the root directory of the drive where it was executed: autorun.inf - also detected as TROJ_SCARECROW.A ComboKill.bat - also detected as TROJ_SCARECROW.A AutoClean\AutoProtect.vbs - also detected as TROJ_SCARECROW.A AutoClean\ComboKill.bat - also detected as TROJ_SCARECROW.A AutoClean\Replicate.vbs - also detected as TROJ_SCARECROW.A AutoClean\shh.bat - also detected as TROJ_SCARECROW.A It checks if the following files exist, most of which are related to other malware:
    • %Windows%\System\lsas.exe
    • %User Profile%\lsass.exe
    • %Windows%\Tasks\Scvhost.exe
    • {drive letter}\RECYCLER {drive letter}\New.exe
    • {drive letter}\start.exe

    If it finds matches, it terminates the process, remove the attributes, Read-only, Hidden, and System of the file, then deletes the associated files and registries. Below is the list of files:

    • %Windows%\System\lsas.exe
    • C:\Documents and Settings\Administrator\lsass.exe
    • %User Profile%\lsass.exe %Windows%\Tasks\Scvhost.exe
    • C:\New.exe %Windows%\Tasks\Scvhost.exe %Windows%\System\bs.pif
    • {drive letter}\RECYCLER {drive letter}\autorun.inf
    • {drive letter}\RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\Desktop.ini
    • {drive letter}\RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213\Autorunme.exe
    • {drive letter}\RECYCLER\S-1-6-21-2434476501-1644491937-600003330-1213
    • {drive letter}\RECYCLER {drive letter}\New.exe {drive letter}\start.exe

    Below is the list of registry entries:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Windows Logistics=

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    LSA Shellu=

    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    Load=

    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar
    BackBitmapIE5=

    HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar
    BackBitmapShell=

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

  SOLUTION

Minimum Scan Engine: 8.900
VSAPI PATTERN File: 7.412.08
VSAPI PATTERN Date: 27 Aug 2010
VSAPI PATTERN Date: 8/27/2010 12:00:00 AM

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

Restart in Safe Mode

[ Learn More ]

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\Microsoft\Windows\CurrentVersion\Run
    • AutoProtect=%Windows%\pchealth\AutoClean\AutoProtect.vbs

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %Windows%\PCHEALTH\AutoClean

Step 5

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