Ransom.Win32.NEMESIS.F

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 drops the following files:

• %User Temp%\{Random Numbers}

(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).)

It drops and executes the following files:

• {Malware Directory}\temp000000.txt

It adds the following processes:

• %System%\cmd.exe /c "vssadmin.exe delete shadows /all /quiet"
• %System%\cmd.exe /c "bcdedit.exe /set {default} recoveryenabled no"
• %System%\cmd.exe /c "bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures"

(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:

• YWgnI24wSXPdcEmX

Ransomware Routine

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

• !!!INSTRUCTION_RNSMW!!!.txt
• boot.ini
• bootfont.bin
• bootmgr
• bootnxt
• bootsect.bak
• google
• intel
• internet explorer
• mozilla firefox
• ntdetect.com
• ntldr
• ntuser.dat
• nvidia
• opera
• pdoxusrs.net
• \windows\

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

• {Infected Directory}\_RESTORE FILES_.txt
• {Malware Directory}\YIHYQML5ZUXXOGETT

It avoids encrypting files with the following file extensions:

• .dll
• .exe
• .lnk
• .sys
• .WECANHELP