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Trojan.Win64.FUPORPLEX.B

April 06, 2020
 Analysis by: Clive Fuentebella
 ALIASES:

HEUR:Trojan.Win32.Vemptik.gen (KASPERSKY); Trojan:Win32/Execution!rfn (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not have any information-stealing capability.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

516,608 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

03 Apr 2020

Payload:

Drops files

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 copies of itself into the affected system:

  • %System Root%\AppPatch\Custom\S{Random characters}.tmp
  • %System Root%\AppPatch\Acp{Random characters}.dll
  • %System%\ms{Random characters}app.dll

(Note: %System Root% is the Windows root folder, where it usually is C:\ 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.)

It adds the following processes:

  • %System%\svchost.exe -k NetworkService

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\ExpServicA

It injects codes into the following process(es):

  • services.exe

Other System Modifications

This Trojan deletes the following files:

  • .tmp files in %System Root%\AppPatch
  • .tmp files in %System Root%\AppPatch\Custom

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

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SENS\Parameters
ServiceDll = %System%\ms{Random characters}app.dll

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SENS
DisplayName = ms{Random characters}app.dll

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SENS
Description = ms{Random characters}app.dll

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SENS
Group = UIGroup

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SENS
ImagePath = %SystemRoot%\system32\svchost.exe -k NetworkSvcGroup

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Information Theft

This Trojan does not have any information-stealing capability.

Other Details

This Trojan does the following:

  • It executes its malicious routine once the following strings are found in its file name:
    • ms
    • app
    • cscdll.dll
    • sens.dll

It deletes itself after execution.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.788.03

FIRST VSAPI PATTERN DATE:

06 Apr 2020

VSAPI OPR PATTERN File:

15.789.00

VSAPI OPR PATTERN Date:

07 Apr 2020

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.XXPE50FFF034

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

Restore this modified 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\SENS\Parameters
    • ServiceDll = %SystemRoot%\System32\sens.dll
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SENS
    • DisplayName = @%SystemRoot%\system32\Sens.dll,-200
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SENS
    • Description = @%SystemRoot%\system32\Sens.dll,-201
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SENS
    • Group = ProfSvc_Group
  • In HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\SENS
    • ImagePath = %SystemRoot%\system32\svchost.exe -k netsvcs -p

Step 6

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.
  • %System Root%\AppPatch\Custom\S{Random characters}.tmp
  • %System Root%\AppPatch\Acp{Random characters}.dll
  • %System%\ms{Random characters}app.dll

Step 7

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