Trojan.Win32.GOLDENSPY.YPAH-B

November 17, 2021
 Analysis by: Patrick Noel Collado
 ALIASES:

Trojan:Win32/Goldenspy.A!MTB (Microsoft), Backdoor.Win32.GoldenHelper.k (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

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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:

2,207,744 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

22 Oct 2021

Payload:

Connects to URLs/IPs, Downloads files

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 files:

  • %Windows%\wmiasssrv.dll (Responsible for writing service and dropping INF file)
  • {File path of parent process}\bmsmam.inf (Responsible for installing the service through UAC bypass technique, deleted afterwards)
  • {File path of parent process}\wmsma.inf (Responsible for installing the service through UAC bypass technique, deleted afterwards)
  • %System%\ms{Random characters}s{Random digits}.dat (Responsible for download mechanism)

(Note: %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.)

It creates the following folders:

  • C:\_skplog
  • %System%\_skplog

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

Autostart Technique

This Trojan starts the following services:

  • Service name: WMPAssis
    Service DLL: %System%\ms{Random characters}s{Random digits}.dat

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

Download Routine

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

  • {Chosen domain from list of domains}/{Chosen route from set of routes}

It saves the files it downloads using the following names:

  • Chosen path among the following paths:
    • {Value for environment variable %ALLUSERPROFILE%}\taxver.exe
    • {Value for environment variable %COMMONPROGRAMFILES%}\taxver.exe
    • {Value for environment variable %WINDIR%}\debug\wia\taxver.exe
    • {Value for environment variable %WINDIR%}\system32\taxver.exe
    • {Value for environment variable %WINDIR%}\taxver.exe
    • {Value for environment variable %WINDIR%}\temp\taxver.exe

Other Details

This Trojan requires the following additional components to properly run:

  • NISEC_SKP.dll
  • Zlib_Tools.dll

It does the following:

  • It installs a service with full system privileges by bypassing UAC.
  • It resolves the IP address of the following domains to be used in choosing the domains, routes, and download path:
    • help.{BLOCKED}lper.ltd
    • help.{BLOCKED}sistant.com
    • help.{BLOCKED}sistant.info
  • It chooses from the following list of domains:
    • info.{BLOCKED}sistant.com
    • info.{BLOCKED}sistant.info
    • info.{BLOCKED}lper.ltd
    • tip.{BLOCKED}lper.ltd
    • bbs.{BLOCKED}lper.info
    • update.{BLOCKED}lper.ltd
    • download.{BLOCKED}lper.com
    • tools.{BLOCKED}per.info
    • update.{BLOCKED}lper.com
  • It chooses from the following list of routes:
    • data/tax32.zip
    • data/taxver.jpg
    • data/msabb.rar
    • data/msabs.dat
    • app/tps32.gif
    • app/taxver.jpg

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

17.198.04

FIRST VSAPI PATTERN DATE:

17 Nov 2021

VSAPI OPR PATTERN File:

17.199.00

VSAPI OPR PATTERN Date:

18 Nov 2021

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.Win32.GOLDENSPY.YPAH-B

[ 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.
  • %Windows%\wmiasssrv.dll (Responsible for writing service and dropping INF file)
  • {File path of parent process}\bmsmam.inf (Responsible for installing the service through UAC bypass technique, deleted afterwards)
  • {File path of parent process}\wmsma.inf (Responsible for installing the service through UAC bypass technique, deleted afterwards)
  • %System%\ms{Random characters}s{Random digits}.dat (Responsible for download mechanism)

Step 5

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.  
  • C:\_skplog
  • %System%\_skplog

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.GOLDENSPY.YPAH-B. 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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