RANSOM_NETCRYPT.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 encrypts files found in specific folders.

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 a copy of itself in the following folders using different file names:

• {malware file path}\{malware file name}.exe

Other System Modifications

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = %User Temp%\rNsmWlppr.bmp

Dropping Routine

This Ransomware drops the following files:

• %User Temp%\rNsmWlppr.bmp

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

Other Details

This Ransomware does the following:

• Upon execution of the malware, it displays the following message box below:

  

• On the previous window, the “no” button will exit the malware while the “yes” will proceed to display the window shown below. Exiting this window will start the encryption routine.

  

• After its encryption routine it shows the following message box:

  

• It sets the file attribute of the running malware file to hidden

Ransomware Routine

This Ransomware encrypts files found in the following folders:

• {system drive}(usually C):\

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

• bootmgr
• BOOTNXT
• hiberfil.sys
• pagefile.sys
• swapfile.sys
• desktop.ini
• NTUSER.DAT
• ntuser.dat
• {malware file name}
• .db
• .lnk

It avoids encrypting files found in the following folders:

• Windows

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

• .encrptd (for files with file extensions)
• .tmpenc.encrptd (for files without file extensions)