TROJ_MERETAM.A

 Analysis by: Maureen Reyes

 ALIASES:

Trojan.Win32.Yakes.wtyq (Kaspersky), Trojan-FPRI!DD197CA3E27D (McAfee)

 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:

342,528 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

16 Jul 2018

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 and executes them:

  • %Application Data%\msnet\{Malware filename}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %Application Data%\Microsoft\Crypto\RSA\{Random name}\{Random GUID}
  • %System%\Tasks\MsSystemWatcher
  • %Application Data%\Microsoft\Windows\Recent\CustomDestinations\d93f411851d7c929.customDestinations-ms

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following processes:

  • cmd.exe /c sc delete WinDefend
  • cmd.exe /c sc stop WinDefend
  • cmd.exe /c powershell Set-MpPreference -DisableRealtimeMonitoring $true

Other System Modifications

This Trojan modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows Defender
DisableAntiSpyware = 1

(Note: The default value data of the said registry entry is 0.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.386.01

FIRST VSAPI PATTERN DATE:

17 Jul 2018

VSAPI OPR PATTERN File:

14.387.00

VSAPI OPR PATTERN Date:

18 Jul 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

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 3

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\SOFTWARE\Policies\Microsoft\Windows Defender
    • From: DisableAntiSpyware = "1"
      To: DisableAntiSpyware = "0"

Step 4

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.
  • %Application Data%\Microsoft\Crypto\RSA\{Random name}\{Random GUID}
  • %Application Data%\Microsoft\Windows\Recent\CustomDestinations\d93f411851d7c929.customDestinations-ms
  • %System%\Tasks\MsSystemWatcher

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_MERETAM.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:


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