Coinminer.Win32.MALXMR.SMBM4

June 27, 2019
 Analysis by: John Donnie Celestre
 ALIASES:

Generic.Application.CoinMiner.1.7A5FEECD (BITDEFENDER); HEUR:RiskTool.Win32.BitCoinMiner.gen (KASPERSKY)

 PLATFORM:

Windows

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

  • Threat Type: Coinminer

  • Destructiveness: No

  • Encrypted:

  • 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 modifies certain registry entries to hide Hidden files.

  TECHNICAL DETAILS

File Size:

1,169,408 bytes

File Type:

EXE

Initial Samples Received Date:

22 Apr 2019

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.

Installation

This Coinminer drops the following files:

  • %System Root%\Chrome\XMR86\xmrcore.exe
  • %User Temp%\aut1380.tmp

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following processes:

  • "%System%\netsh.exe" firewall add allowedprogram "{Executed Malware Directory}\{Malware File Name}.exe" "xmrcore.exe" ENABLE

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

It creates the following folders:

  • %System Root%\Chrome\XMR86

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

Autostart Technique

This Coinminer creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
%System Root%\Chrome\xmrcore.exe = "{Executed Malware Directory}\{Malware File Name}.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
%System Root%\Chrome\XMR86\xmrcore.exe = "{Executed Malware Directory}\{Malware File Name}.exe"

Other Details

This Coinminer connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.159.106
  • {BLOCKED}.{BLOCKED}.141.36

It modifies the following registry entries to hide Hidden files:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = 0

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.598.05

FIRST VSAPI PATTERN DATE:

31 Oct 2018

VSAPI OPR PATTERN File:

14.599.00

VSAPI OPR PATTERN Date:

01 Nov 2018

Step 1

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 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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • %System Root%\Chrome\xmrcore.exe = "{Executed Malware Directory}\{Malware File Name}.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • %System Root%\Chrome\XMR86\xmrcore.exe = "{Executed Malware Directory}\{Malware File Name}.exe"

Step 5

Search and delete this file

[ 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%\Chrome\XMR86\xmrcore.exe
  • %User Temp%\aut1380.tmp

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System Root%\Chrome\XMR86

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Coinminer.Win32.MALXMR.SMBM4. 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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