Author: Patrick Noel Collado   
 Modified By:: Khristian Joseph Morales

 

Ransom:Win32/BlackCat.MK!MTB (MICROSOFT)

 PLATFORM:

Windows

 OVER ALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE
Low
Medium
High
Critical

  • Threat Type:
    Ransomware

  • Destructiveness:
    No

  • Encrypted:
    No

  • In the wild:
    Yes

  OVERVIEW

INFECTION CHANNEL: Downloaded from the Internet

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

  TECHNICAL DETAILS

File size: 3,081,216 bytes
File type: EXE
Memory resident: No
INITIAL SAMPLES RECEIVED DATE: 03 февраля 2022
PAYLOAD: Displays graphics/image, 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.

Installation

This Ransomware adds the following processes:

  • "%System%\cmd.exe" /c "fsutil behavior set SymlinkEvaluation R2L:1"
  • "%System%\cmd.exe" /c "fsutil behavior set SymlinkEvaluation R2R:1"
  • "%System%\cmd.exe" /c "iisreset.exe /stop"
  • "%System%\cmd.exe" /c "reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters /v MaxMpxCt /d 65535 /t REG_DWORD /f"
  • "%System%\cmd.exe" /c "vssadmin.exe delete shadows /all /quiet"
  • "%System%\cmd.exe" /c "arp -a"
  • "%System%\cmd.exe" /c "cmd.exe /c for /F \"tokens=*\" %1 in ('wevtutil.exe el') DO wevtutil.exe cl \"%1\""
  • "%System%\cmd.exe" /c "vssadmin.exe delete shadows /all /quiet"
  • "%System%\cmd.exe" /c "bcdedit /set {default}"
  • "%System%\cmd.exe" /c "bcdedit /set {default} recoveryenabled No"

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

Other System Modifications

This Ransomware adds the following registry entries:

HKCU\Control Panel\Desktop
Wallpaper = %Desktop%\RECOVER-cygzsl2-FILES.txt.png

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

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Owner = {Hex Values} → Deletes afterwards

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Sequence = 1 → Deletes afterwards

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
RegFiles0000 = {FilePath\{FileName} → Deletes afterwards

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
RegFilesHash = {Hex Values} → Deletes afterwards

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
SessionHash = {Hex Values} → Deletes afterwards

Process Termination

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

  • mepocs
  • memtas
  • veeam
  • svc$
  • backup
  • sql
  • vss
  • msexchange
  • sql$
  • mysql
  • mysql$
  • sophos
  • MSExchange
  • MSExchange$
  • WSBExchange
  • PDVFSService
  • BackupExecVSSProvider
  • BackupExecAgentAccelerator
  • BackupExecAgentBrowser
  • BackupExecDiveciMediaService
  • BackupExecJobEngine
  • BackupExecManagementService
  • BackupExecRPCService
  • GxBlr
  • GxVss
  • GxClMgrS
  • GxCVD
  • GxCIMgr
  • GXMMM
  • GxVssHWProv
  • GxFWD
  • SAPService
  • SAP
  • SAP$
  • SAPD$
  • SAPHostControl
  • SAPHostExec
  • QBCFMonitorService
  • QBDBMgrN
  • QBIDPService
  • AcronisAgent
  • VeeamNFSSvc
  • VeeamDeploymentService
  • VeeamTransportSvc
  • MVArmor
  • MVarmor64
  • VSNAPVSS
  • AcrSch2Svc

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

  • agntsvc
  • dbeng50
  • dbsnmp
  • encsvc
  • excel
  • firefox
  • infopath
  • isqlplussvc
  • msaccess
  • mspub
  • mydesktopqos
  • mydesktopservice
  • notepad
  • ocautoupds
  • ocomm
  • ocssd
  • onenote
  • oracle
  • outlook
  • powerpnt
  • sqbcoreservice
  • sql
  • steam
  • synctime
  • tbirdconfig
  • thebat
  • thunderbird
  • visio
  • winword
  • wordpad
  • xfssvccon
  • *sql*
  • bedbh
  • vxmon
  • benetns
  • bengien
  • pvlsvr
  • beserver
  • raw_agent_svc
  • vsnapvss
  • CagService
  • QBIDPService
  • QBDBMgrN
  • QBCFMonitorService
  • SAP
  • TeamViewer_Service
  • TeamViewer
  • tv_w32
  • tv_x64
  • CVMountd
  • cvd
  • cvfwd
  • CVODS
  • saphostexec
  • saposcol
  • sapstartsrv
  • avagent
  • avscc
  • DellSystemDetect
  • EnterpriseClient
  • VeeamNFSSvc
  • VeeamTransportSvc
  • VeeamDeploymentSvc

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000

It does the following:

  • Accepts the following arguments:
    • --access-token Access Token
    • --bypass ...
    • --child Run as child process
    • --drag-and-drop Invoked with drag and drop
    • --drop-drag-and-drop-target Drop drag and drop target batch file
    • --extra-verbose Log more to console
    • -h, --help Print help information
    • --log-file Enable logging to specified file
    • --no-net Do not discover network shares on Windows
    • --no-prop Do not self propagate(worm) on Windows
    • --no-prop-servers ... Do not propagate to defined servers
    • --no-vm-kill Do not stop VMs on ESXi
    • --no-vm-kill-names ... Do not stop defined VMs on ESXi
    • --no-vm-snapshot-kill Do not wipe VMs snapshots on ESXi
    • --no-wall Do not update desktop wallpaper on Windows
    • -p, --paths ... Only process files inside defined paths
    • --propagated Run as propagated process
    • --ui Show user interface
    • -v, --verbose Log to console
  • Terminate Esxi VMs
  • Clear event logs
  • It uses PsExec to propagate

Ransomware Routine

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

  • desktop.ini
  • autorun.inf
  • ntldr
  • bootsect.bak
  • thumbs.db
  • boot.ini
  • ntuser.dat
  • iconcache.db
  • bootfont.bin
  • ntuser.ini
  • ntuser.dat.log

It avoids encrypting files found in the following folders:

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

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

  • .cygzsl2

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

  • {Infected Directory}\RECOVER-cygzsl2-FILES.txt
  • %Desktop%\RECOVER-cygzsl2-FILES.txt.png -- Set as wallpaper

It avoids encrypting files with the following file extensions:

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

  SOLUTION

Minimum scan engine: 9.800
First VSAPI Pattern File: 17.328.05
First VSAPI Pattern Release Date: 20 января 2022
VSAPI OPR PATTERN-VERSION: 17.329.00
VSAPI OPR PATTERN DATE: 21 января 2022

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.XXPE50FFF053

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

[ learnMore ]

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\RestartManager\Session0000
    • Owner = {Hex Values}
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • SessionHash = {Hex Values}
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • Sequence = 1
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • RegFiles0000 = {FilePath\{FileName}
  • In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
    • RegFilesHash = {Hex Values}

Step 5

Delete this registry key

[ learnMore ]

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\RestartManager\Session0000

Step 6

Search and delete these files

[ learnMore ]
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.
  • %Desktop%\RECOVER-cygzsl2-FILES.txt.png
  • {Infected Directory}\RECOVER-cygzsl2-FILES.txt

Step 7

Scan your computer with your Trend Micro product to delete files detected as Ransom.Win32.BLACKCAT.SMYXBLK. 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:

Step 8

Restore encrypted files from backup.

Step 9

Reset your Desktop properties

[ learnMore ]


Did this description help? Tell us how we did.