Ransom.Win32.AVADDON.YJAF-A

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 may be downloaded by other malware/grayware from remote sites.

It encrypts files found in specific folders. 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.

It may be downloaded by the following malware/grayware from remote sites:

• Trojan.JS.AVADDON.YJAF-A

Installation

This Ransomware drops the following copies of itself into the affected system:

• %Application Data%\{malware filename}.exe

(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).)

It adds the following processes:

• wmic.exe SHADOWCOPY /nointeractive
• wbadmin DELETE SYSTEMSTATEBACKUP
• wbadmin DELETE SYSTEMSTATEBACKUP -deleteOldest
• bcdedit.exe /set {default} recoveryenabled No
• bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures
• vssadmin.exe Delete Shadows /All /Quiet

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
update = %Application Data%\{malware filename}.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
update = %Application Data%\{malware filename}.exe

Other System Modifications

This Ransomware adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Owner = {HEX VALUES}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
SessionHash = {HEX VALUES}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
Sequence = {VALUE}

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000
RegFiles0000 = {Target File Name}

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

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0

(Note: The default value data of the said registry entry is 1.)

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

(Note: The default value data of the said registry entry is None.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
ConsentPromptBehaviorAdmin = 0

(Note: The default value data of the said registry entry is 5.)

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Profile%\bckgrd.bmp

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:

• ccEvtMgr
• ccSetMgr
• Culserver
• dbeng8
• dbsrv12
• DefWatch
• Intuit.QuickBooks.FCS
• msmdsrv
• QBCFMonitorService
• QBIDPService
• RTVscan
• sqladhlp
• SQLADHLP
• sqlagent
• sqlbrowser
• sqlservr
• sqlwriter
• tomcat6
• VMAuthdService
• VMnetDHCP
• VMUSBArbService
• vmware-converter
• VMwareHostd
• vmware-usbarbitator64

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

• 360doctor.exe
• 360se.exe
• axlbridge.exe
• BCFMonitorService.exe
• Culture.exe
• Defwatch.exe
• fdhost.exe
• fdlauncher.exe
• GDscan.exe
• httpd.exe
• java.exe
• MsDtSrvr.exe
• QBDBMgr.exe
• QBIDPService.exe
• QBIDPService.exe
• qbupdate.exe
• QBW32.exe
• RAgui.exe
• RTVscan.exe
• sqlbrowser.exe
• sqlservr.exe
• supervise.exe
• tomcat6.exe
• wdswfsafe.exe
• winword.exe
• wxServer.exe
• wxServerView.exe

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0000

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0001

HKEY_CURRENT_USER\Software\Microsoft\
RestartManager\Session0002

It connects to the following URL(s) to get the affected system's IP address:

• api.myip.com

It does the following:

• Terminates itself if Windows Locale ID is equal to the following:
  • 419 = Russian
  • 422 = Ukrainian
• Terminates itself if machine is set to the following keyboard layout language:
  • 419 = Russian
  • 485 = Yakut(Russia)
  • 444 = Tatar
  • 422 = Ukrainian
• This ransomware affects all existing drives in the system

It adds the following scheduled tasks:

• Task Name: update
• Task to run: %Application Data%\{Malware Filename}.exe
• Trigger: At {install time} every day - After triggered, repeat every 10 minutes indefinitely

(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).)

Ransomware Routine

This Ransomware encrypts files found in the following folders:

• Program Files\Microsoft\Exchange Server
• Program Files (x86)\Microsoft\Exchange Server
• Program Files\Microsoft SQL Server
• Program Files (x86)\Microsoft SQL Server

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

• bckgrd.bmp

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

• Windows
• Program Files
• Users\All Users
• %User Temp%
• Program Files (x86)
• %User Profile%\AppData
• ProgramData
• Tor Browser

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

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

• .avdn

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

• {Encrypted Directory}\{random numbers}-readme.html
  

It avoids encrypting files with the following file extensions:

• .bin
• .dat
• .dll
• .drv
• .exe
• .ini
• .lnk
• .prf
• .rdp
• .swp
• .sys
• .avdn