TROJ_RANSOM.IHN

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.

It executes then deletes itself afterward.

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:

• %Application Data%\africa.bmp
• %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\africa.bmp
• %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\cleen.bat - deletes the initial malware and the deletes the batch file itself

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It executes then deletes itself afterward.

Autostart Technique

This Trojan drops the following file(s) in the Windows Common Startup folder to enable its automatic execution at every system startup:

• %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\{malware file name and extension} - Copy of itself

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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 System Modifications

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

HKEY_CURRENT_USER\Control Panel\Desktop
Wallpaper = "%Application Data%\africa.bmp"

HKEY_CURRENT_USER\Control Panel\Desktop
TileWallpaper = "0"

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

Other Details

This Trojan encrypts files with the following extensions:

• .jpg
• .jpeg
• .doc
• .rtf
• .xls
• .zip
• .db3
• .rar
• .7z
• .docx
• .pdf
• .odt
• .ppt
• .mdb
• .dwg
• .xml
• .dt
• .gsf
• .ppsx
• .pptx
• .xlsx
• .1cd
• .dbf

It renames encrypted files using the following names:

• {file name and extension}.sos@{BLOCKED}e.com_T3

NOTES:

This Trojan encrypts files using RSA encryption, which needs a private key from the cybercriminal in order to decrypt the encrypted files.