Analysis by: Raymart Christian Yambot

ALIASES:

Ransom:Win32/Qilin (MICROSOFT)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

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

  TECHNICAL DETAILS

File Size: 7,363,640 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 05 Aug 2024
Payload: Disables AV, Drops files, Encrypts files, Terminates processes

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:

  • %Public%\psexec0.exe
  • %Public%\{Malware File Name} → Copy of itself
  • %Public%\{10 Random Characters}.bat → Deleted Afterward

(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 adds the following processes:

  • cmd /C %Public%\{10 Random Characters}.bat
  • cmd /C fsutil behavior set SymlinkEvaluation R2L:1
  • cmd /C fsutil behavior set SymlinkEvaluation R2R:1
  • cmd /C iisreset.exe /stop
  • cmd /C vssadmin.exe Delete Shadows /all /quiet
  • cmd /C wmic.exe Shadowcopy Delete
  • cmd /C bcdedit /set {default}
  • cmd /C bcdedit /set {default} recoveryenabled No
  • cmd /C “for /F 'tokens=*' %1 in ('wevtutil.exe el') DO wevtutil.exe cl %1”
  • cmd /C reg add HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters /v MaxMpxCt /d 65535 /t REG_DWORD /f
  • cmd /C sc stop {service}
  • cmd /C taskkill /IM {process}* /F

(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.)

Process Termination

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

  • via net stop /y:
    • WSearch
    • MSExchangeIS
    • MSExchangeSA
    • MSExchangeADTopology
    • wuauserv
    • eventlog
    • MSSQLSERVER
    • SQLSERVERAGENT
    • SQLBrowser
    • MSSQLServerOLAPService
    • ReportServer
    • MsDtsServer
    • SQLWriter

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

  • via taskkill /F /IM:
    • agntsvc
    • dbeng50
    • dbsnmp
    • encsvc
    • excel
    • firefox
    • infopath
    • isqlplussvc
    • msaccess
    • mspub
    • mydesktopq
    • mydesktopservic
    • notepad
    • ocautoupds
    • ocomm
    • ocssd
    • onenote
    • oracle
    • outlook
    • powerpnt
    • sqbcoreservic
    • steam
    • synctime
    • tbirdconfig
    • thebat
    • thunderbird
    • visio
    • winword
    • wordpad
    • xfssvccon
    • *sql*
    • bedbh
    • vxmon
    • benetns
    • bengien
    • pvlsvr
    • beserver
    • raw_agent_svc
    • vsnapvss
    • CagService
    • QBCFMonitorSe
    • TeamViewer_Service
    • TeamViewertv_w32
    • tv_x64
    • CVMountd
    • cvd
    • cvfwd
    • CVODS
    • saphostexe
    • saposcol
    • sapstartsrv
    • avagent
    • avscc
    • DellSystem
    • EnterpriseClient
    • VeeamNFSSVc
    • VeeamTransportSvc
    • VeeamDeploymentSvc

Ransomware Routine

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

  • \$Windows.~WS
  • \$windows.~ws
  • \$WINDOWS.~WS
  • \$windows.~bt
  • \$Windows.~BT
  • \$WINDOWS.~BT
  • \Windows.old
  • \NTUSER.DAT
  • \ntuser.dat
  • \autorun.inf
  • \boot.ini
  • \desktop.ini
  • \system volume information
  • \Boot
  • \DumpStack.log.tmp
  • \PerfLogs
  • \Users\
  • \Microsoft_Corporation\
  • \AppData\Local\Microsoft\GameDVR
  • \AppData\Local\Packages\Microsoft
  • \AppData\

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

  • {Original file name}.{Original extension}.tu5s6r

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

  • {Encrypted Directory}\RECOVER-jtu5s6r-DATA.txt

It avoids encrypting files with the following file extensions:

  • .exe
  • .EXE
  • .DLL
  • .ini
  • .inf
  • .pol
  • .cmd
  • .ps1
  • .vbs
  • .bat
  • .pagefile.sys
  • .hiberfil.sys
  • .drv
  • .msc
  • .dll
  • .lock
  • .sys
  • .msu
  • .lnk
  • .search-ms
  • .config

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 19.602.03
FIRST VSAPI PATTERN DATE: 20 Sep 2024
VSAPI OPR PATTERN File: 19.603.00
VSAPI OPR PATTERN Date: 21 Sep 2024

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

Restart in Safe Mode

[ Learn More ]

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

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.  
  • DROP
  • %Public%\psexec0.exe
  • %Public%\{Malware File Name}
  • %Public%\{10 Random Characters}.bat
  • {Encrypted Directory}\RECOVER-jtu5s6r-DATA.txt

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Ransom.Win64.CICADA.YXEHE. 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 6

Restore encrypted files from backup.


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