TROJ_RANSOM.AQB

This Trojan infects the Master Boot Record (MBR) of an affected system. It restarts the system afterwards and shows a ransom message, urging users to pay an amount in order to reverse the effect.

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

This Trojan infects the MBR of the system it affects. Once executed, the malware copies the original MBR and overwrites it with its code.

It displays a certain message that tells the user that the system is locked and they must pay through an electronic payment service in order to have their systems unlocked.

Should the user pay the required amount of money, the attacker sends them a code to unlock the system. The OS resumes loading and the infected MBR removed.

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 copies of itself into the affected system and executes them:

• %User Temp%\x2z8.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

It drops the following non-malicious file:

• %User Temp%\fpath.txt

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

NOTES:

This Trojan infects the MBR of the affected system. Once executed, this malware copies the original MBR and overwrites it with its code.

After writing its code, it automatically restarts the system to let the infection take effect. When the system restarts, the users see the following message:

The message on the screen prompts the users that the system is blocked and ask to pay 920 hryvnia (UAH) via QIWI, an electronic payment service, to a purse number (12 digits) - 380682699268. It also writes that after the payment is sent, the user is given a code to unlock the system.

If the user pays for the code, the OS resumes loading and the infected MBR is removed. The infected MBR is detected by Trend Micro as BOOT_RANSOM.AQB.