TROJ_RANSOM.QOWA

This Trojan ransomware uses social engineering methods to lure users into performing certain actions that may, directly or indirectly, cause malicious routines to be performed. Specifically, it disables functionality of the compromised computer so that victims are forced to dial a premium-rate SMS number.

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

This ransomware consistently displays an image which users from accessing their desktops and applications. Users are then forced to provide the required ransom by dialing the premium-rate SMS number displayed on the screen.

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

It uses icons similar to those of legitimate applications to entice a user to click them.

Arrival Details

This Trojan may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following copies of itself into the affected system:

• %System%\usrinit.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = %System%\userinit.exe,%System%\usrinit.exe

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Propagation

This Trojan uses icons similar to those of legitimate applications to entice a user to click them.

Other Details

This Trojan does the following:

• Displays the following image in a consistent manner after this Trojan executes, preventing users from accessing their desktops and applications:
  

  Users are then forced to provide the required "ransom" by dialing the premium-rate SMS number displayed on the screen.