Ransom.Win64.MEDUSALOCKER.AA

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.

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:

• vssadmin.exe Resize ShadowStorage /for=c: /on=c: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=c: /on=c: /maxsize=unbounded
• vssadmin.exe Resize ShadowStorage /for=d: /on=d: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=d: /on=d: /maxsize=unbounded
• vssadmin.exe Resize ShadowStorage /for=e: /on=e: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=e: /on=e: /maxsize=unbounded
• vssadmin.exe Resize ShadowStorage /for=f: /on=f: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=f: /on=f: /maxsize=unbounded
• vssadmin.exe Resize ShadowStorage /for=g: /on=g: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=g: /on=g: /maxsize=unbounded
• vssadmin.exe Resize ShadowStorage /for=h: /on=h: /maxsize=401MB
• vssadmin.exe Resize ShadowStorage /for=h: /on=h: /maxsize=unbounded
• vssadmin.exe Delete Shadows /All /Quiet
• del /s /f /q c:\*.VHD c:\*.bac c:\*.bak c:\*.wbcat c:\*.bkf c:\Backup*.* c:\backup*.* c:\*.set c:\*.win c:\*.dsk
• del /s /f /q d:\*.VHD d:\*.bac d:\*.bak d:\*.wbcat d:\*.bkf d:\Backup*.* d:\backup*.* d:\*.set d:\*.win d:\*.dsk
• del /s /f /q e:\*.VHD e:\*.bac e:\*.bak e:\*.wbcat e:\*.bkf e:\Backup*.* e:\backup*.* e:\*.set e:\*.win e:\*.dsk
• del /s /f /q f:\*.VHD f:\*.bac f:\*.bak f:\*.wbcat f:\*.bkf f:\Backup*.* f:\backup*.* f:\*.set f:\*.win f:\*.dsk
• del /s /f /q g:\*.VHD g:\*.bac g:\*.bak g:\*.wbcat g:\*.bkf g:\Backup*.* g:\backup*.* g:\*.set g:\*.win g:\*.dsk
• del /s /f /q h:\*.VHD h:\*.bac h:\*.bak h:\*.wbcat h:\*.bkf h:\Backup*.* h:\backup*.* h:\*.set h:\*.win h:\*.dsk
• del %0
• bcdedit.exe /set {default} recoveryenabled No
• bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
• wbadmin DELETE SYSTEMSTATEBACKUP
• wmic.exe SHADOWCOPY /nointeractive
• %System%\cmd.exe /c del {Malware File Path}\{Malware File Name}.exe >>NUL → delete itself after execution

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

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

• {8761ABBD-7F85-42EE-B272-A76179687C63}

Autostart Technique

This Ransomware adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MSFEEditor = "{Malware File Path}\{Malware File Name.exe}" e

It starts the following services:

• LanmanWorkstation

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnabledLinkedConnections = 1

Process Termination

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

• ccEvtMgr
• ccSetMgr
• Culserver
• DefWatch
• Intuit.QuickBooks.FCS
• MsDtsServer100
• msmdsrv
• MSSQLFDLauncher
• MSSQLSERVER
• MSSQLServerADHelper100
• MSSQLServerOLAPService
• QBCFMonitorService
• QBIDPService
• ReportServer
• RTVscan
• SavRoam
• sqladhlp
• SQLADHLP
• sqlagent
• sqlbrowser
• SQLBrowser
• SQLSERVERAGENT
• sqlservr
• sqlwriter
• SQLWriter
• wrapper

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

• axlbridge.exe
• Culture.exe
• Defwatch.exe
• fdhost.exe
• fdlauncher.exe
• httpd.exe
• MsDtsSrvr.exe
• onenotem.exe
• QBCFMonitorService.exe
• QBDBMgr.exe
• QBIDPService.exe
• qbupdate.xe
• QBW32.exe
• RAgui.exe
• RTVscan.exe
• sqlbrowser.exe
• sqlmangr.exe
• sqlservr.exe
• sqlwriter.exe
• ssms.exe
• supervise.exe
• winword.exe
• Winword.exe
• wxServer.exe
• wxServerView

Dropping Routine

This Ransomware drops the following files:

• %Application Data%\KEY.FILE

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Other Details

This Ransomware does the following:

• This ransomware affects all existing drives in the system
• It also encrypts files from network shares.
• It uses Windows Restart Manager to unlock files it will encrypt.
• It empties the recycle bin

Ransomware Routine

This Ransomware appends the following extension to the file name of the encrypted files:

• .inprocess
• .ReadInstructions

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

• %SystemRoot%\Recovery_Instructions.txt
• {Drive Letter}:\Recovery_Instructions.txt
• %Public%\Desktop\ Recovery_Instructions.txt
  

It avoids encrypting files with the following file extensions:

• .TXT
• .txt
• .exe
• .dll
• .sys
• .ini
• .lnk
• .dat