Trojan:W32/AutoIt.D attempts to download and install other malware to the system. It also changes startup and search pages of the Internet Explorer web browser.
Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.
AutoIt.D is a script file converted to an executable file using AutoIt.
AutoIt.D may be silently downloaded on the system when an unsuspecting user follows a link delivered in a malicious chat message in the Yahoo! Messenger Instant Messaging (IM) application, such as below:
When present on an infected computer, the malware is able to hijack the IM application in order to send out the malicious chat messages. The Trojan searches for the string title "Yahoo! Messenger" in the Windows Title Bar in order to detect whe the application is open.
When the string found, AutoIt.D will secretly and randomly input any of the following messages at 80 second intervals:
The links in the messages direct the user to a webpage containing the malware:
The malware is then silently installed and executed on the visitor's system.
Upon execution, AutoIt.D downloads a file from the following site:
This file is detected as IM-Worm:W32/Sohanad.B. Once downloaded, it is saved with the following filename:
The saved file is then executed.
AutoIt.D also changes settings for the web browser's Home Page, Yahoo Buzz and Yahoo Launchcast links to the following site:
To enable its automatic execution on startup, it creates the following registry launch point:
It locks the home page in Internet Explorer by modifying the following registry entry:
Note: The value of Homepage varies between users. Homepage="0" will unlock the homepage settings.
It also disables Task Manager and Registry Editor by creating the following registry entries:
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