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BKDR_LAVAGOK.ZAGL

January 07, 2020
 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Backdoor 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:

57,977 bytes

File Type:

COM

Memory Resident:

Yes

Initial Samples Received Date:

07 Jan 2020

Arrival Details

This Backdoor 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 Backdoor adds the following processes:

  • "%System%\rundll32.exe" %System%\shell32.dll,OpenAs_RunDLL {malware file path and name}
  • {malware file path and name}
  • %System%\svchost.exe -k netsvcs
  • %System%\vssvc.exe
  • %Windows%\Microsoft.NET\Framework\v4.0.30319\mscorsvw.exe
  • %System%\svchost.exe -k LocalServiceAndNoImpersonation
  • %Windows%\Microsoft.NET\Framework64\v4.0.30319\mscorsvw.exe
  • %System%\sppsvc.exe
  • "%System Root%\Program Files\Windows Media Player\wmpnetwk.exe"
  • %System%\svchost.exe -k WerSvcGroup
  • %System%\WerFault.exe -u -p 2348 -s 1252
  • %System%\WerFault.exe -u -p 700 -s 1532
  • %System%\WerFault.exe -u -p 700 -s 1444
  • %System%\WerFault.exe -u -p 700 -s 824
  • %System%\WerFault.exe -u -p 1828 -s 212
  • %System%\WerFault.exe -u -p 2740 -s 180
  • %System%\WerFault.exe -u -p 2740 -s 176
  • %System%\WerFault.exe -u -p 2740 -s 172

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

It creates the following folders:

  • %Windows%\ServiceProfiles\NetworkService\AppData\Local\Microsoft

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

Other System Modifications

This Backdoor deletes the following files:

  • %Windows%\LastGood.Tmp

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

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
FileExts\OpenWithList

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\VSS\Diag\
Registry Writer

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\VSS\Diag\
COM+ REGDB Writer

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\VSS\Diag\
ASR Writer

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\VSS\Diag\
Shadow Copy Optimization Writer

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\HomeGroup\
UIStatusCache

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
SessionInfo\1\WHCIconStartup

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\Adobe\Acrobat Reader DC\
Reader
AcroRd32.exe = "Adobe Acrobat Reader DC "

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Windows%\eHome
ehshell.exe = "Windows Media Center"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%System%
mspaint.exe = "Paint"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\MICROS~1\Office12
OIS.EXE = "Microsoft Office Picture Manager"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\Windows Photo Viewer
PhotoViewer.dll = "Windows Photo Viewer"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%System Root%\Program Files\VMware\
VMware Tools
VMwareHostOpen.exe = "Default Host Application"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\Microsoft Office\Office12
WINWORD.EXE = "Microsoft Office Word"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\Windows Media Player
wmplayer.exe = "Windows Media Player"

HKEY_CURRENT_USER\Software\Classes\
Local Settings\Software\Microsoft\
Windows\Shell\MuiCache\
%Program Files%\Windows NT\Accessories
WORDPAD.EXE = "WordPad"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\HomeGroup\
UIStatusCache
UIStatus = "560"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\HomeGroup\
UIStatusCache
OnlyMember = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\NetworkList\
Nla\Cache\Intranet
{89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbc\x079"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
cval = "0"

Dropping Routine

This Backdoor drops the following files:

  • %All Users Profile%\Microsoft\Windows\DRM\drmstore.hds
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb

(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). . %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local 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 BKDR_LAVAGOK.ZAGL

[ 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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts
    • OpenWithList
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Diag
    • Registry Writer
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Diag
    • COM+ REGDB Writer
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Diag
    • ASR Writer
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\VSS\Diag
    • Shadow Copy Optimization Writer
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\HomeGroup
    • UIStatusCache
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\SessionInfo\1
    • WHCIconStartup

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\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\Adobe\Acrobat Reader DC\Reader
    • AcroRd32.exe = "Adobe Acrobat Reader DC "
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Windows%\eHome
    • ehshell.exe = "Windows Media Center"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%System%
    • mspaint.exe = "Paint"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\MICROS~1\Office12
    • OIS.EXE = "Microsoft Office Picture Manager"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\Windows Photo Viewer
    • PhotoViewer.dll = "Windows Photo Viewer"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%System Root%\Program Files\VMware\VMware Tools
    • VMwareHostOpen.exe = "Default Host Application"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\Microsoft Office\Office12
    • WINWORD.EXE = "Microsoft Office Word"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\Windows Media Player
    • wmplayer.exe = "Windows Media Player"
  • In HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell\MuiCache\%Program Files%\Windows NT\Accessories
    • WORDPAD.EXE = "WordPad"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\HomeGroup\UIStatusCache
    • UIStatus = "560"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\HomeGroup\UIStatusCache
    • OnlyMember = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Nla\Cache\Intranet
    • {89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbc\x079"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • cval = "0"

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\Windows\DRM\drmstore.hds
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb

Step 6

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%\ServiceProfiles\NetworkService\AppData\Local\Microsoft

Step 7

Scan your computer with your Trend Micro product to delete files detected as BKDR_LAVAGOK.ZAGL. 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 8

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\LastGood.Tmp


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