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: 954,368 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 23 May 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 Root%//1.exe
  • "%System%\cmd.exe" /c del %User Temp%\8A6202~1.EXE > nul
  • "%System%\WScript.exe" "%System Root%\2612.vbs"
  • %System Root%\2612.vbs
  • %All Users Profile%\Application Data\Storm\update\Terms.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%\svchost.exe -k netsvcs
  • %All Users Profile%\Application Data\Storm\update\Terms.exe Win7
  • %System%\WerFault.exe -u -p 2128 -s 1252
  • %System%\WerFault.exe -u -p 2364 -s 212
  • %System%\WerFault.exe -u -p 2264 -s 1232
  • %System%\WerFault.exe -u -p 2712 -s 52
  • %System%\WerFault.exe -u -p 1696 -s 1256
  • %System%\WerFault.exe -u -p 676 -s 1532
  • %System%\WerFault.exe -u -p 676 -s 1528
  • %System%\WerFault.exe -u -p 676 -s 1536
  • %System%\WerFault.exe -u -p 2660 -s 200
  • %System%\WerFault.exe -u -p 344 -s 180
  • %System%\WerFault.exe -u -p 344 -s 172
  • %System%\WerFault.exe -u -p 344 -s 176
  • %System%\WerFault.exe -u -p 680 -s 220

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %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). . %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

It creates the following folders:

  • %All Users Profile%\Application Data\Storm\update
  • %All Users Profile%\Application Data\Storm

(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). )

Autostart Technique

This Backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Efghij
ImagePath = "%All Users Profile%\Application Data\Storm\update\Terms.exe"

Other System Modifications

This Backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\Efghij
MarkTime = "2020-01-23 18:53"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\Efghij
Description = "Efghijkl Nopqrstuv Xyabcde Ghijklmn Pqr"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\Efghij
MarkTime = "2020-01-23 18:54"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\NetworkList\
Nla\Cache\Intranet
{89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbc\x0f\x1d"

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Efghij
DisplayName = "Efghij Lmnopqrs Uvwxyabc Efgh"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Efghij
Start = "SERVICE_AUTO_START"

Dropping Routine

This Backdoor drops the following files:

  • %All Users Profile%\Microsoft\Windows\DRM\drmstore.hds
  • %System Root%\2612.vbs
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb
  • %System Root%\1.exe
  • %All Users Profile%\Application Data\Storm\update\Terms.exe

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

Other Details

This Backdoor connects to the following possibly malicious URL:

  • {BLOCKED}.99.160

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 Backdoor.Win32.ZEGOST.WLDF

[ 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 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\CurrentControlSet\services\Efghij
    • MarkTime = "2020-01-23 18:53"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Efghij
    • Description = "Efghijkl Nopqrstuv Xyabcde Ghijklmn Pqr"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Efghij
    • MarkTime = "2020-01-23 18:54"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Nla\Cache\Intranet
    • {89BCDCB3-5725-45A2-94AB-2D6B641209B0} = "\x00PV\xbc\x0f\x1d"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • cval = "0"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Efghij
    • DisplayName = "Efghij Lmnopqrs Uvwxyabc Efgh"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Efghij
    • Start = "SERVICE_AUTO_START"

Step 4

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
  • %System Root%\2612.vbs
  • %All Users Profile%\Microsoft\Windows\DRM\v3ks.sec
  • %AppDataLocal%\Microsoft\Media Player\CurrentDatabase_372.wmdb
  • %System Root%\1.exe
  • %All Users Profile%\Application Data\Storm\update\Terms.exe

Step 5

Search and delete these folders

[ 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.
  • %All Users Profile%\Application Data\Storm\update
  • %All Users Profile%\Application Data\Storm

Step 6

Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win32.ZEGOST.WLDF. 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:


Did this description help? Tell us how we did.