RANSOM_XORIST.SMA

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 is capable of encrypting files in the affected system.

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 copies of itself into the affected system:

• %User Temp%\{random value}.exe

(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.)

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

• %User Profile%\Desktop\HOW TO DECRYPT FILES.txt
• %All Users Profile%\Microsoft\Windows\Start Menu\Programs\Startup\HOW TO DECRYPT FILES.txt
• {folders containing encrypted files}\HOW TO DECRYPT FILES.txt

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.)

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
Alcmeter = %User Temp%\{random value}.exe

Other System Modifications

This Trojan adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.EnCiPhErEd
(Default) = "EADQEVCXIGGSVPB"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
EADQEVCXIGGSVPB
(Default) = "CRYPTED!"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
EADQEVCXIGGSVPB\DefaultIcon
(Default) = "%User Temp%\{random value}.exe,0"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
EADQEVCXIGGSVPB\shell\open\
command
(Default) = "%User Temp%\{random value}.exe"

Other Details

This Trojan renames encrypted files using the following names:

• {original filename and extension}.EnCiPhErEd

It is capable of encrypting files in the affected system.