Analysis by: Mc Justine De Guzman
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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: 1,352,192 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 04 Mar 2021

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.

Other Details

Based on analysis of the codes, it has the following capabilities:

  • Delete the following files:
    • %System%\mscor.dll
    • %System%\WinRing0x64.sys
  • Delete the following service:
    • MicrosoftCoreLib

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

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
services\MicrosoftCoreLib\Parameters
ServiceDll = %System%\mscor.dll

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
mscor = MicrosoftCoreLib

It does the following:

  • It only creates one of the listed two registries
  • It adds and runs the following service:
    • Service name: MicrosoftCoreLib
    • Service display name: Microsoft Core Lib
    • Imagepath: %System%\svchost.exe -k mscor

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 16.574.08
FIRST VSAPI PATTERN DATE: 04 Mar 2021
VSAPI OPR PATTERN File: 16.575.00
VSAPI OPR PATTERN Date: 05 Mar 2021

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.XXPE50FFF042

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

Disable this malware service

[ Learn More ]
    • MicrosoftCoreLib

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\MicrosoftCoreLib\Parameters
    • ServiceDll = %System%\mscor.dll
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • mscor = MicrosoftCoreLib

Step 7

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


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