Trojan.Win32.RANUMBOT.SYFV

 Analysis by: Maria Emreen Viray

 ALIASES:

Trojan:Win32/RanumBot!rfn (MICROSOFT)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

It does not have any propagation routine.

It does not have any backdoor routine.

  TECHNICAL DETAILS

File Size:

1,983,488 bytes

File Type:

EXE

File Compression:

UPX

Memory Resident:

No

Initial Samples Received Date:

25 Nov 2020

Payload:

Connects to URLs/IPs, Downloads files, Executes 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 adds the following folders:

  • %User Temp%\csrss
  • %User Temp%\csrss\wup
  • %User Temp%\csrss\wup\xarch

(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).)

It adds the following processes:

  • %User Temp%\csrss\wup\xarch\wup.exe
  • if %Windows%\rss\csrss.exe exists:
    • %Windows%\rss\csrss.exe -hide {PID of wup.exe}

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\xwupMUTEX31337
  • Global\xmrigMUTEX31337 → checking for running downloaded wup.exe

Propagation

This Trojan does not have any propagation routine.

Backdoor Routine

This Trojan does not have any backdoor routine.

Rootkit Capabilities

This Trojan does not have rootkit capabilities.

Download Routine

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

  • If OS is 32 bit:
    • https://{BLOCKED}ndiff.com/{16 randomly generated hex values}/xme32-635-gcc.exe
    • http://x.{BLOCKED}ndiff.com/{16 randomly generated hex values}/xme32-635-gcc.exe
  • If OS is 64 bit:
    • https://{BLOCKED}ndiff.com/{16 randomly generated hex values}/xme64-635.exe

It saves the files it downloads using the following names:

  • %User Temp%\csrss\wup\xarch\wup.exe
    • If 32 bit, detected as Coinminer.Win32.MALXMR.SMBM4
    • If 64 bit, detected as Coinminer.Win64.MALXMR.TIAOODGF

(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).)

Other Details

This Trojan does the following:

  • Continues with routine if one of the following keys and corresponding entries exists:
    • HKEY_CURRENT_USER\{User SID}\Software\Microsoft\TestApp
      UUID = {string data}
      OSArchitecture = {64 or 32}
      Servers = {multi string data}
    • HKEY_CURRENT_USER\{User SID}\Software\Microsoft\{hex generated from SID}
      UUID = {string data}
      OSArchitecture = {64 or 32}
      Servers = {multi string data}
  • attempts to hide wup.exe process using the following malicious component exists:
    • %Windows%\rss\csrss.exe

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

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

16.372.08

FIRST VSAPI PATTERN DATE:

25 Nov 2020

VSAPI OPR PATTERN File:

16.373.00

VSAPI OPR PATTERN Date:

26 Nov 2020

Step 1

Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:

     
    • Troj.Win32.TRX.XXPE50FFF039

Step 2

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 3

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 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%\csrss\wup\xarch\wup.exe

Step 5

Search and delete this folder

[ 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.
  • %User Temp%\csrss
  • %User Temp%\csrss\wup
  • %User Temp%\csrss\wup\xarch

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win32.RANUMBOT.SYFV. 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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