Trojan:W32/AutoIt.D

AutoIt.D is a script file converted to an executable file using AutoIt.

Distribution

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:

• A new dangerous computer virus that can destroys all your data has just been released . Click here to know how to avoid it : http://www.geocities.co.jp/ie_[...] <<
• Cac ban co the tranh bi nhiem cac loai virus online gan day bang cach update Windows . Vao day de biet cach Update Win ma ko can ban quyen Windows xin: http://www.geocities.co.jp/ie_[...]
• cai dit con me may day . Lua tao a` ? Xem di : http://www.geocities.co.jp/tha[...] X-(
• cool girls : http://www.geocities.co.jp/tha[...] :x:x:x:x:x
• di'nh virus ru`i =)) du`ng cai nay ma diet na`y : http://www.geocities.co.jp/ie_[...]
• Download free MP3s : http://www.geocities.co.jp/tha[...] <<
• ha`i dek chiu dc =)) http://www.geocities.co.jp/tha[...] =)) =))
• have you ever seen such a silly man like this ? http://www.geocities.co.jp/tha[...] =))
• Just check out my new personal website : http://www.geocities.co.jp/tha[...] C00l !!!
• Let's vote for Miss Vietnam - Mai Phuong Thuy - for the upcoming Miss World championship : http://www.geocities.co.jp/tha[...] !!
• making money online never be easier : http://www.geocities.co.jp/tha[...] >:D<
• Now you can avoid some critical online viruses by updating Windows . Click here to know how to Update your Windows : http://www.geocities.co.jp/tha[...]
• the only way to clean some online viruses that may lead you into troubles : http://www.geocities.co.jp/ie_[...] <<
• Use this tool to remove the viruses from your PC : http://www.geocities.co.jp/ie_[...] <<
• wtf is this ? Wanna give me a shit ? http://www.geocities.co.jp/tha[...] X-( <<

The links in the messages direct the user to a webpage containing the malware:

• http://my.opera.com/termex18388/homes/files/[...].exe
• http://www.geocities.co.jp/thanatos18388/[...].jpg

The malware is then silently installed and executed on the visitor's system.

Execution

Upon execution, AutoIt.D downloads a file from the following site:

• http://www.geocities.co.jp/thanatos18388/[...].jpg

This file is detected as IM-Worm:W32/Sohanad.B. Once downloaded, it is saved with the following filename:

• %WinDir%\svchost32.exe

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:

• http://www.geocities.co.jp/th[...]

Registry

To enable its automatic execution on startup, it creates the following registry launch point:

• [HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run] Task Manager ="%WinDir%\svchost32.exe"

It locks the home page in Internet Explorer by modifying the following registry entry:

• [HKEY_CURRENT_USER\Software\Policies\Microsoft\Internet Explorer\Control Panel] Homepage="1"

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:

• [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System] DisableTaskMgr="1"
• [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System] DisableRegistryTools="1"