Analysis by: Johnlery Triunfante
 PLATFORM:

Windows

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

  • Threat Type: Coinminer

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel: Dropped by other malware

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 executes then deletes itself afterward.

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

  TECHNICAL DETAILS

File Size: 1,118,720 bytes
File Type: EXE
Initial Samples Received Date: 21 Mar 2018
Payload: Drops files

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:

  • %All Users Profile%\Microsoft\clr_optimization_v4.0.53738 _64\csrss.exe

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 copies of itself into the affected system:

  • %All Users Profile%\clr_optimization_v4.0.53738 _64\svchsot.exe

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 creates the following folders:

  • %All Users Profile%\clr_optimization_v4.0.53738 _64
  • %All Users Profile%\Microsoft\clr_optimization_v4.0.53738 _64

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 executes then deletes itself afterward.

Other Details

This Coinminer does the following:

  • It installs itself as service to enable its automatic execution:
    • Service Name:clr_optimization_v4.0.53738 _64
    • Service Path:%All Users Profile%\clr_optimization_v4.0.53738 _64\svchsot.exe

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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 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.