Analysis by: Nikko Tamana
ALIASES:

TrojanDownloader:PowerShell/CoinMiner (Microsoft)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:

  • 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.

It downloads a file from a certain URL then renames it before storing it in the affected system. It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 740 bytes
File Type: PS1
Memory Resident: No
Initial Samples Received Date: 11 Jan 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.

It may be downloaded from the following remote sites:

  • http://94.177{BLOCKED}3/css/bootstrap.css

Installation

This Trojan adds the following processes:

  • cmd.exe /c %ProgramData%\spoosvc.exe -o pool.sup{BLOCKED}mr.com -u 45KCADTpEL1eiRJmjHfVAkCzgy8wR19uuZ7mfYkXKUEjhCjpxwQYeRViAb3PTdjRPyMyFth7c6PihEwCBjWSH9uX8uksGhm -p n -k -B --max-cpu-usage=50 --donate-level=1

Download Routine

This Trojan downloads files from the following URLs then renames them before storage in the affected system:

  • http://94.17{BLOCKED}23/css/bootstrap.css
  • http://94.17{BLOCKED}23/css/6Ov4ZHOg.exe

It saves the files it downloads using the following names:

  • %ProgramData%\spoosvc.exe
  • %ProgramData%\msupdate.ps1

(Note: %ProgramData% is the Program Data folder, where it usually is C:\Program Files in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData in 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 then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

Other Details

This Trojan does the following:

    • It creates the following scheduled task:
    • TaskName: Spooler SubSystem Service
    • Triggers: Repeat task every 6 minutes
    • Actions: powershell.exe -ExecutionPolicy bypass -windowstyle hidden -noexit -File $env:programdata\msupdate.ps1

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.898.05
FIRST VSAPI PATTERN DATE: 11 Jan 2018
VSAPI OPR PATTERN File: 13.899.00
VSAPI OPR PATTERN Date: 12 Jan 2018

Step 1

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 2

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

Step 3

Scan your computer with your Trend Micro product and note files detected as TROJ_DLOADR.AUSUHI

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.
  • %ProgramData%\spoosvc.exe
  • %ProgramData%\msupdate.ps1

Step 5

Delete the Scheduled Tasks added by this malware/grayware

[ Learn More ]

To delete the added Scheduled Task file:

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

  1. Open the Windows Scheduled Tasks. To do this, click Start>Programs>Accessories>System Tools>Scheduled Tasks.
  2. Double-click on a .JOB file.
  3. Check if the malware path and file name exists in the .JOB file. To do this, check the value in the Run field.
  4. If found, select the .JOB file then press SHIFT+DELETE to permanently delete the file.
  5. Repeat the steps above for the remaining .JOB files.

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 of the Task Scheduler Window, click Task Scheduler Library.
  3. In the upper-middle panel, click a Task.
  4. In the lower middle panel, click the Actions tab
  5. Check if the malware path and file name exists in the task. To do this, check the value in the Details column under the Actions tab.
  6. If found, select the task and press DELETE and click Yes to delete the task.
  7. Repeat the steps above for the remaining tasks.

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADR.AUSUHI. 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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