Ransom.Win32.BLACKCAT.SMYXBLK
Ransom:Win32/BlackCat.MK!MTB (MICROSOFT)
Windows
Threat Type: Ransomware
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
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
3,081,216 bytes
EXE
No
03 Feb 2022
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
- --access-token
- 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
- 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
9.800
17.328.05
20 Jan 2022
17.329.00
21 Jan 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
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}
- Owner = {Hex Values}
- In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
- SessionHash = {Hex Values}
- SessionHash = {Hex Values}
- In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
- Sequence = 1
- Sequence = 1
- In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
- RegFiles0000 = {FilePath\{FileName}
- RegFiles0000 = {FilePath\{FileName}
- In HKEY_CURRENT_USER\Software\Microsoft\RestartManager\Session0000
- RegFilesHash = {Hex Values}
- RegFilesHash = {Hex Values}
Step 5
Delete this registry key
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
- %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
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