Analysis by: Wilbert Vidal
 Modified by: Johnlery Triunfante
 PLATFORM:

Windows

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:

  • Threat Type: Coinminer

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

This Coinminer arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It uses the system's central processing unit (CPU) and/or graphical processing unit (GPU) resources to mine cryptocurrency.

  TECHNICAL DETAILS

File Size: 140,449 bytes
File Type: PS1
Memory Resident: Yes
Initial Samples Received Date: 15 Feb 2018

Arrival Details

This Coinminer arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This Coinminer adds and runs the following services:

  • DusmrtSvc → Executes the contents found in HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai\Vendor

Other System Modifications

This Coinminer deletes the following files:

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai
Content = {Base64 encoded string}

HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai
Vendor = {Base64 encoded string}

HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai
Version = {contents of xm64.txt/xm86.txt which are encrypted coin mining component}

Other Details

This Coinminer does the following:

  • It reflectively loads and executes its coin mining component in the memory.
  • Before it add its service, it deletes the following service name to ensure that it has no duplicate service name:
    • DusmrtSvc
  • It suspends the execution of its coin mining component if it finds a running process that contains the following strings:
    • taskmgr
    • wireshark
    • processhacker
    • procexp
    • procexp64
    • procmon

It uses the system's central processing unit (CPU) and/or graphical processing unit (GPU) resources to mine cryptocurrency. This behavior makes the system run abnormally slow.

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.970.03
FIRST VSAPI PATTERN DATE: 16 Feb 2018
VSAPI OPR PATTERN File: 13.971.00
VSAPI OPR PATTERN Date: 16 Feb 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

Restart in Safe Mode

[ Learn More ]

Step 4

Disable this malware service

[ Learn More ]
    • DusmrtSvc

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\SOFTWARE\SasaiKudasai
    • Content = {Base64 encoded string}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai
    • Vendor = {Base64 encoded string}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\SasaiKudasai
    • Version = {contents of xm64.txt/xm86.txt which are encrypted coin mining component}

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Coinminer_MALXMR.DB-PS. 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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