TROJ_RANSOM.HUN

This ransomware variant targets users in Hungary. It locks users' computers and lists the encrypted file types. It also lists steps to unlock the files, along with the ransom amount.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Arrival Details

This Trojan 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 Trojan drops the following files:

• %System Root%\w.bmp

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

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

• %Windows%\system\cl32.dll

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

It drops the following copies of itself into the affected system:

• %Windows%\system\csrss.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

It adds the following processes:

• iexplore.exe
      Launch http://szelvesz.2u.se/hun

Autostart Technique

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

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
MS = "{Malware Path}\{Malware Filename}.exe}"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
cmd.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
command.com

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
dllhost.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
mbam.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
msconfig.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
regedit.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
rstrui.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\
taskmgr.exe

Process Termination

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

• taskmgr.exe
• msconfig.exe
• rundll32.exe
• cmd.exe
• mbam.exe
• rstrui.exe

Other Details

This Trojan encrypts files with the following extensions:

• *.jpeg
• *.jpg
• *.doc
• *.png
• *.gif
• *.mp3
• *.mp4
• *.wav
• *.docx
• *.rtf
• *.txt
• *.pps
• *.ppt
• *.pptx
• *.m4a
• *.mid
• *.wmv
• *.wma
• *.mpg
• *.mov
• *.avi
• *.3gp
• *.psd
• *.xls
• *.xlxs
• *.html
• *.php
• *.zip
• *.rar
• *.bak

It requires the existence of the following files to properly run:

• {Malware Path}\CL32.dll

NOTES:

This Trojan creates the following registry entries to prevent execution of system and security tools:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Image File Execution Options\{app name}
Debugger = "%System Root%\die.exe"

The variable {app name} may be any of the following:

• cmd.exe
• command.com
• dllhost.exe
• mbam.exe
• msconfig.exe
• regedit.exe
• rstrui.exe
• taskmgr.exe

It appends .ENC to encrpyted files. It locks the user's system and displays the following: