Analysis by: Jeffrey Francis Bonaobra
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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: 23,375,872 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 26 May 2022

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %Windows%\essp.tmp
  • %Windows%\nssm.exe

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

It adds the following processes:

  • %Windows%\nssm.exe install nssmsevr powershell.exe -NoP -NonI -ep bypass -e {Base 64-encoded command}
  • %Windows%\essp.tmp
  • %System%\Macromed\Temp\{{GUID}}\FlashPlayerInstaller.exe -relaunched
  • %System%\Macromed\Temp\{{GUID}}\InstallFlashPlayer.exe -install -skipARPEntry -iv 1 -au 4294967295

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

Autostart Technique

This Trojan 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\nssmsevr
ImagePath = %Windows%\nssm.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\EventLog\Application\
NSSM
EventMessageFile = %Windows%\nssm.exe

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\EventLog\Application\
NSSM
TypesSupported = 7

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nssmsevr\Parameters
Application = powershell.exe

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nssmsevr\Parameters
AppParameters = -NoP -NonI -ep bypass -e {Base 64-encoded command}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nssmsevr\Parameters
AppDirectory =

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\nssmsevr\Parameters\
AppExit

Other Details

This Trojan connects to the following possibly malicious URL:

  • https://fpdownload.{BLOCKED}edia.com
  • http://fpdownload2.{BLOCKED}edia.com/get/flashplayer/update/current/install/version.xml{BLOCKED}.{BLOCKED}.0.192~installVector=101&previousVersion=0.0.0.0&pProc=err9&lang=en&cpuWordLength=64&playerType=ax&

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 17.602.03
FIRST VSAPI PATTERN DATE: 02 Jun 2022
VSAPI OPR PATTERN File: 17.603.00
VSAPI OPR PATTERN Date: 03 Jun 2022

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF057

Step 2

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 3

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

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\EventLog\Application\NSSM
    • EventMessageFile = %Windows%\nssm.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Application\NSSM
    • TypesSupported = 7
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters
    • Application = powershell.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters
    • AppParameters = -NoP -NonI -ep bypass -e {Base 64-encoded command}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr
    • ImagePath = %Windows%\nssm.exe

Step 6

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\EventLog\Application\NSSM
    • EventMessageFile
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\EventLog\Application\NSSM
    • TypesSupported
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters
    • Application
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters
    • AppParameters
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr
    • ImagePath
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters
    • AppDirectory
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\nssmsevr\Parameters\AppExit

Step 7

Search and delete these files

[ 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.
  • %Windows%\essp.tmp
  • %Windows%\nssm.exe

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win64.CVE20170144.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 9

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win64.CVE20170144.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:


Did this description help? Tell us how we did.