Analysis by: Bren Matthew Ebriega


Win32:DangerousSig [Trj] (AVAST)




  • Threat Type: Ransomware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes


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.

However, as of this writing, the said sites are inaccessible.

It drops files as ransom note. It avoids encrypting files with the following file extensions.


File Size: 1,884,776 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 24 Apr 2021
Payload: Collects system information, Displays message/message boxes, Terminates processes, Encrypts files

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.


This Ransomware drops the following files:

  • %All Users Profile%\{Generated Extension}.ico → Icon for encrypted files.
  • %All Users Profile%\{Generated Extension}.BMP → Used as wallpaper.

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

It adds the following processes:

  • {Malware Directory}\{Malware Filename} -work worker{Number} job{Number}-{4-Digit Number} → For every drive that it will encrypt.

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

  • Global\{32-Hex Characters generated from Machine GUID}

Other System Modifications

This Ransomware adds the following registry entries as part of its installation routine:

.{Generated Extension}
(Default) = {Generated Extension}

{Generated Extension}\DefaultIcon
(Default) = %All Users Profile%\{Generated Extension}.ico

It changes the desktop wallpaper by modifying the following registry entries:

HKEY_USERS\{USER SID}\Control Panel\
Wallpaper = %All Users Profile%\{Generated Extension}.BMP

HKEY_USERS\{USER SID}\Control Panel\
WallpaperStyle = 10

It sets the system's desktop wallpaper to the following image:

Process Termination

This Ransomware terminates the following services if found on the affected system:

  • vss
  • sql
  • svc$
  • memtas
  • mepocs
  • sophos
  • veeam
  • backup
  • GxVss
  • GxBlr
  • GxFWD
  • GxCVD
  • GxCIMgr

It terminates the following processes if found running in the affected system's memory:

  • sql
  • oracle
  • ocssd
  • dbsnmp
  • synctime
  • agntsvc
  • isqlplussvc
  • xfssvccon
  • mydesktopservice
  • ocautoupds
  • encsvc
  • firefox
  • tbirdconfig
  • mydesktopqos
  • ocomm
  • dbeng50
  • sqbcoreservice
  • excel
  • infopath
  • msaccess
  • mspub
  • onenote
  • outlook
  • powerpnt
  • steam
  • thebat
  • thunderbird
  • visio
  • winword
  • wordpad
  • notepad

Information Theft

This Ransomware gathers the following data:

  • Username
  • Computer Name
  • Domain Name
  • OS Information (Type, Version, Architecture)
  • System Language
  • Drives Information (Drive Names, Drive Space)

Stolen Information

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

  • bar{BLOCKED}

Other Details

This Ransomware adds the following registry keys:

.{Generated Extension}

{Generated Extension}

{Generated Extension}\DefaultIcon

It does the following:

  • It checks computer's language and will terminate itself if any of the following language is detected:
    • Arabic
    • Armenian
    • Azerbaijani
    • Belarusian
    • Georgian
    • Kazakh
    • Kyrgyz
    • Romanian
    • Russian
    • Tajik
    • Tatar
    • Turkmen
    • Ukranian
    • Uzbek
  • It checks if it is running with a privilege level that is on SYSTEM level. If it is not, it will do the following:
    • If it is running on a non-administrator account and the os version is Windows 7 or above it will use the Elevated COM Object UAC Bypass technique to execute an instance of itself with SYSTEM level privilege.
    • If it is running on an administrator account it would add the following service then start and use the service to execute an instance of itself with SYSTEM level privilege. The service is deleted after it is used.
      • Service Name: .{Generated Extension}
      • Binary Pathname: {Malware Directory}\{Malware Filename}
  • It searches for files to encrypt in fixed drives, removable drives, and network resources.
  • It empties the recycle bin.
  • It deletes shadow copies.

However, as of this writing, the said sites are inaccessible.

Ransomware Routine

This Ransomware avoids encrypting files with the following strings in their file name:

  • autorun.inf
  • boot.ini
  • bootfont.bin
  • bootsect.bak
  • desktop.ini
  • iconcache.db
  • ntldr
  • ntuser.dat
  • ntuser.dat.log
  • ntuser.ini
  • thumbs.db
  • README.{Generated Extension}.TXT

It avoids encrypting files with the following strings in their file path:

  • $recycle.bin
  • config.msi
  • $windows.~bt
  • $windows.~ws
  • windows
  • appdata
  • application data
  • boot
  • google
  • mozilla
  • program files
  • program files (x86)
  • programdata
  • system volume information
  • tor browser
  • windows.old
  • intel
  • msocache
  • perflogs
  • x64dbg
  • public
  • all users
  • default

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

  • .{8-Hex Characters generated from Machine GUID}

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

  • {Encrypted Directory}\README.{Generated Extension}.TXT

It avoids encrypting files with the following file extensions:

  • .386
  • .adv
  • .ani
  • .bat
  • .bin
  • .cab
  • .cmd
  • .com
  • .cpl
  • .cur
  • .deskthemepack
  • .diagcab
  • .diagcfg
  • .diagpkg
  • .dll
  • .drv
  • .exe
  • .hlp
  • .icl
  • .icns
  • .ico
  • .ics
  • .idx
  • .ldf
  • .lnk
  • .mod
  • .mpa
  • .msc
  • .msp
  • .msstyles
  • .msu
  • .nls
  • .nomedia
  • .ocx
  • .prf
  • .ps1
  • .rom
  • .rtp
  • .scr
  • .shs
  • .spl
  • .sys
  • .theme
  • .themepack
  • .wpx
  • .lock
  • .key
  • .hta
  • .msi
  • .pdb
  • .{Generated Extension}


Minimum Scan Engine: 9.800
VSAPI OPR PATTERN File: 16.677.00
VSAPI OPR PATTERN Date: 25 Apr 2021

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.XXPE50FFF043

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

Identify and terminate files detected as Ransom.Win32.DARKSIDE.FAIO

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\SOFTWARE\Classes\.{Generated Extension}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\{Generated Extension}

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.
  • %All Users Profile%\{Random characters}.ico
  • {Encrypted Directory}\README.{Generated Extension}.TXT
  • %All Users Profile%\{Generated Extension}.BMP

Step 8

Reset your Desktop properties

[ Learn More ]

Step 9

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win32.DARKSIDE.FAIO. 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 10

Restore encrypted files from backup.

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