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TROJ_COINMINER.THAAEH

February 07, 2018
 Analysis by: Camille Reyes
 ALIASES:

Backdoor:MSIL/Minerbot.A (MICROSOFT); Trojan-Dropper.MSIL.Mine.fk (KASPERSKY)

 PLATFORM:

Windows

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

  • 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.

  TECHNICAL DETAILS

File Size:

1,763,328 bytes

Memory Resident:

No

Initial Samples Received Date:

25 Dec 2017

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 the following copies of itself into the affected system:

  • %Application Data%\Windows\{original file name}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 files:

  • %User Startup%\Webhost.url
  • %Windows%\Temp\fwtsqmfile00.sqm
  • %Windows%\SoftwareDistribution\DataStore\Logs\edb.chk
  • %System%\wbem\Performance\WmiApRpl_new.h

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Webhost = %Application Data%\Windows\{original file name}.exe

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}.{BLOCKED}.55.248/cmd.php?hwid=8AA7DEE7
  • http://{BLOCKED}er.com:443

It does the following:

  • Create a schedule task via: schtasks /create /tn \System\SecurityServiceUpdate /tr %Application Data%\Windows\{original file name}.exe /st 00:00 /du 9999:59 /sc daily /ri 5 /f

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.906.02

FIRST VSAPI PATTERN DATE:

15 Jan 2018

VSAPI OPR PATTERN File:

13.907.00

VSAPI OPR PATTERN Date:

16 Jan 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

Deleting Scheduled Tasks

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 that has the following value in the Schedule column:
    System\SecurityServiceUpdate
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the following string:
    Cmd /c /rd /s /q C:
  5. If the said string is found, 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 that has the value in the Triggers column:
    System\SecurityServiceUpdate
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the following string:
    Cmd /c /rd /s /q C:
  5. If the said string is found, delete the task..

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Webhost = %Application Data%\Windows\{original file name}.exe

Step 6

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.
  • %Application Data%\Windows\{original file name}.exe
  • %User Startup%\Webhost.url
  • %Windows%\Temp\fwtsqmfile00.sqm
  • %Windows%\SoftwareDistribution\DataStore\Logs\edb.chk
  • %System%\wbem\Performance\WmiApRpl_new.h

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_COINMINER.THAAEH. 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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