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Trojan.Win64.DRIDEX.AM

October 31, 2019
 Analysis by: John Donnie Celestre
 ALIASES:

Trojan:Win32/Dridex.PK!MTB (Microsoft); HEUR:Trojan.Win32.Generic (Kaspersky); Troj/Dridex-ABA (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 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 retrieves specific information from the affected system.

  TECHNICAL DETAILS

File Size:

679,936 bytes

File Type:

DLL

Memory Resident:

No

Initial Samples Received Date:

29 Oct 2019

Payload:

Drops files, Modifies system registry, Steals information

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:

  • %Application Data%\{random characters}\{file name}.exe → legitimate Windows executable
    The file name can be any of the .exe files located in %System% directory.
  • %Application Data%\{random characters}\{executable's dll name}.dll → detected as Trojan.Win64.DRIDEX.AM
  • %System%\{random characters}\{file name}.exe → legitimate Windows executable
    The file name can be any of the .exe files located in %System% directory.
  • %System%\{random characters}\{executable's dll name}.dll → detected as Trojan.Win64.DRIDEX.AM

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

It creates the following folders:

  • %Application Data%\{random characters}
  • %System%\{random characters}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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

  • {hash of computer name and user name}

It injects codes into the following process(es):

  • explorer.exe

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
Olxdkxkrdtg = "%Application Data%\{random characters}\{file name}.exe"

It drops the following file(s) in the Windows User Startup folder to enable its automatic execution at every system startup:

  • %User Startup%\{random characters}.lnk

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CLSID\{GUID}\ShellFolder

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
CLSID\{GUID}\ShellFolder
{GUID} = {hex values}

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0

Information Theft

This Trojan retrieves the following information from the affected system:

  • OS Version
  • Computer Name
  • User Name
  • Install Date
  • Running Privilege

Other Details

This Trojan does the following:

  • It executes the following command to bypass Windows Firewall:
    • netsh advfirewall firewall add rule name="Core Networking - Multicast Listener Done (ICMPv4-In)" program="C:\Windows\Explorer.EXE" dir=in action=allow protocol=TCP localport=any → allows explorer.exe to listen on any port
  • It listens on port 443.

It adds the following scheduled tasks:

  • Task name: {random characters}
    Trigger: Every 1 hour
    Task to be run: %System%\{random characters}\{file name}.exe

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

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.344.04

FIRST VSAPI PATTERN DATE:

04 Sep 2019

VSAPI OPR PATTERN File:

15.345.00

VSAPI OPR PATTERN Date:

05 Sep 2019

Step 1

Trend Micro products with the XGen technology detect this malware as

[ Learn More ]
 
  • Troj.Win32.TRX.XXPE50FFF031

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

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
    • {random characters}= "%Application Data%\{random characters}\{file name}.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\CLSID\{GUID}\ShellFolder
    • {GUID} = {hex values}

Step 5

Restore this modified 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\Policies\System
    • From: EnableLUA = 0
      To: EnableLUA = 1

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\CLSID\{GUID}\ShellFolder
    • (null)

Step 7

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%\{random characters}\{file name}.exe
  • %Application Data%\{random characters}\{executable's dll name}.dll
  • %System%\{random characters}\{file name}.exe
  • %System%\{random characters}\{executable's dll name}.dll
  • %User Startup%\{random characters}.lnk

Step 8

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.
  • %Application Data%\{random characters}
  • %System%\{random characters}

Step 9

Scan your computer with your Trend Micro product to delete files detected as Trojan.Win64.DRIDEX.AM. 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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