Analysis by: Neljorn Nathaniel Aguas
ALIASES:

Trojan:Win32/Danabot.MBFW!MTB (MICROSOFT)

 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.

It does not have any propagation routine.

It does not have any backdoor routine.

It does not have any information-stealing capability.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size: 1,981,440 bytes
File Type: EXE
File Compression: UPX
Memory Resident: Yes
Initial Samples Received Date: 29 Mar 2024
Payload: Connects to URLs/IPs, Hides files and processes

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:

  • %ProgramData%\Drivers\csrss.exe → attributes set to HIDDEN and SYSTEM

(Note: %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

It drops the following files:

  • %User Temp%\{Random Characters}\cached-certs
  • %User Temp%\{Random Characters}\cached-microdesc-consensus
  • %User Temp%\{Random Characters}\cached-microdescs.new
  • %User Temp%\{Random Characters}\lock
  • %User Temp%\{Random Characters}\state
  • %User Temp%\{Random Characters}\unverified-microdesc-consensus

(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:

  • {Malware Path}\{Malware Filename}

It creates the following folders:

  • %User Temp%\{Random Characters}
  • %User Temp%\{Random Characters}\key
  • %ProgramData%\Drivers → attributes set to HIDDEN

(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).. %ProgramData% is a version of the Program Files folder where any user on a multi-user computer can make changes to programs. This contains application data for all users. This is usually C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit), or C:\Documents and Settings\All Users on Windows Server 2003(32-bit), 2000(32-bit) and XP.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
CSRSS = "%ProgramData%\Drivers\csrss.exe"

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\System\Config
i = {Generated Hash Value}

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.

Information Theft

This Trojan does not have any information-stealing capability.

Other Details

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\System

HKEY_LOCAL_MACHINE\System\Config

It connects to the following website to send and receive information:

  • http:/{BLOCKED}mfco6oqxsqd.onion/task.php?n={Generated Hash Value}&v={Malware Version}&b={Build Number}&p={Plugins}&nocache=1712674784

It does the following:

  • It uses brute-force technique using a dictionary containing a list of email and passwords to gain administrative access to target websites.
  • It targets websites using the following Web Content Management System (CMS) for its brute-force attacks:
    • DataLife Engine
    • Drupal
    • Joomla
    • Magento
    • OpenCart
    • WordPress
  • It attempts to gain administrative access to websites using CMS by appending the following paths to the URLs:
    • /admin
    • /admin/
    • /admin.php
    • /admin/index.php
    • /administrator/
    • /administrator/index.php
    • /index.php
    • /login/index.php
    • /phpmyadmin/
    • /PhpMyAdmin/
    • /pma
    • /pma/
    • /user/login
    • /wp-admin/
    • /wp-login.php
  • It uses the following network protocols and ports to authenticate each credential:
    • FTP
      • Ports:
        • 21
        • 990
    • IMAP
      • Ports:
        • 143
        • 220
        • 993
    • POP3
      • Ports:
        • 110
        • 995
    • SMTP
      • Ports:
        • 25
        • 26
        • 465
        • 587
        • 2525
        • 3535
    • SSH
      • Ports:
        • 22
        • 222
        • 2222
  • It connects with the C&C Server using a Tor Client.
  • It uses multiple relays in the Tor network to ensure anonymous communication.

It does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.272.06
FIRST VSAPI PATTERN DATE: 11 Apr 2024
VSAPI OPR PATTERN File: 19.273.00
VSAPI OPR PATTERN Date: 12 Apr 2024

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.XXPE50FFF079

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

Restart in Safe Mode

[ Learn More ]

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • CSRSS = %ProgramData%\Drivers\csrss.exe
  • In HKEY_LOCAL_MACHINE\System\Config
    • i = {Generated Hash Value}

Step 6

Delete this registry key

[ 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_LOCAL_MACHINE\System\
    • Config
  • In HKEY_LOCAL_MACHINE\
    • System

Step 7

  1. Open a command prompt.
    • For Windows 7 users, click Start, enter CMD in the Find input field, and press Enter.
  2. In the CMD console, enter the following:

    ATTRIB [+R | -R] [+A | -A ] [+S | -S] [+H | -H] [+I | -I] [drive:][path][filename] [/S [/D] [/L]]

    Where:
    + Activates an attribute
    - Disables an attribute
    R Read-only file attribute
    A Archive file attribute
    S System file attribute
    H Hidden file attribute
    I Indexed file attribute without content
    [drive:][path][filename]
    Specifies one or more files in the current folder and all its subfolders
    /S Processes the corresponding files in the current folder and all its subfolders
    /D Process folders
    /L Act on the attributes of the symbolic link instrad of the target of the symbolic link
    Example:
    To make all files and folders (including subfolders visible in drive D:
    ATTRIB –H D:\* /S /D
  3. Repeat the step above for folders and files from other drives or directories.

Step 8

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%\Drivers\csrss.exe
  • %User Temp%\{Random Characters}\cached-certs
  • %User Temp%\{Random Characters}\cached-microdesc-consensus
  • %User Temp%\{Random Characters}\cached-microdescs.new
  • %User Temp%\{Random Characters}\lock
  • %User Temp%\{Random Characters}\state
  • %User Temp%\{Random Characters}\unverified-microdesc-consensus

Step 9

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.
  • %User Temp%\{Random Characters}\key
  • %User Temp%\{Random Characters}
  • %ProgramData%\Drivers

Step 10

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.CMSBRUTE.NLJ. 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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