Ransom.Win32.NEMTY.THEOGBO

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 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.

Installation

This Ransomware adds the following processes:

• %System%\cmd.exe ipconfig
• %System%\cmd.exe net user

(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:

• off white air force cveta kapusti :)

Other System Modifications

This Ransomware changes the desktop wallpaper by modifying the following registry entries:

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\god.jpg

It sets the system's desktop wallpaper to the following image:

• %User Temp%\god.jpg
  

Download Routine

This Ransomware downloads the file from the following URL and renames the file when stored in the affected system:

• http://ocsp.{BLOCKED}i.goog/gsr2/ME4wTDBKMEgwRjAJBgUrDgMCGgUABBTgXIsxbvr2lBkPpoIEVRE6gHlCnAQUm%2BIHV2ccHsBqBt5ZtJot39wZhi4CDQHjtJ13zfQMBhkWtuM%3D
• http://ocsp.{BLOCKED}i.goog/gts1d2/MFEwTzBNMEswSTAJBgUrDgMCGgUABBT4YwNSyUnwC88de5a5l4eUO%2BLQewQUsd0yXei3N3LSzlzOJv5HeeIBCOkCEFuEnqWAwrdaCgAAAAAl4Dc%3D
• http://api.{BLOCKED}p.com/v2/free/{external ip}/countryName

It saves the files it downloads using the following names:

• %Temporary Internet Files%\Content.IE5\{7 random characters}\raw[1].txt
• %Temporary Internet Files%\Content.IE5\{7 random characters}\countryName[1].txt
• %User Temp%\ip.txt
• %User Temp%\country.txt

(Note: %Temporary Internet Files% is the Temporary Internet Files folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temporary Internet Files on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Microsoft\Windows\Temporary Internet Files on Windows Vista, 7 and 2008(64-bit), or C:\Users\{user name}\AppData\Local\Microsoft\Windows\INetCache on Windows 8, 8.1, 2012(64-bit) and 10(64-bit).. %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).)

Other Details

This Ransomware adds the following registry keys:

HKEY_CURRENT_USER\Software\TESORION
fileid = NEMTY_{7 random characters}

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

• www.myexternalip.com

It drops the following file(s)/component(s):

• %Cookies%\{username}@db-ip[1].txt

(Note: %Cookies% is the Internet Explorer browser cookies folder, which is usually C:\Documents and Settings\{user name}\Cookies on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Cookies on Windows Vista and 7, or C:\Users\{user name}\AppData\Local\Microsoft\Windows\INetCookies on Windows 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

Ransomware Routine

This Ransomware encrypts files found in the following folders:

• Removable Drive
• Network Drive
• Fixed Drive

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

• windows
• $RECYCLE.BIN
• NTDETECT.COM
• MSDOS.SYS
• IO.SYS
• boot.ini
• AUTOEXEC.BAT
• ntuser.dat
• desktop.ini
• CONFIG.SYS
• RECYCLER
• BOOTSECT.BAK
• bootmgr
• programdata
• appdata
• program files
• program files (x86)

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

• (encrytpted files}.NEMTY_{7 random characters}

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

• {Encrypted File Directory}\NEMTY_{7 random characters}-DECRYPT.txt
  

It avoids encrypting files with the following file extensions:

• .exe
• .log
• .cab
• .cmd
• .com
• .cpl
• .ini
• .dll
• .url
• .ttf
• .mp3
• .pif
• .mp4
• .NEPHILIM
• .msi
• .lnk
• .NEMTY