Name :	AutoIt.D
Size:	181,472 bytes
Category:	Malware
Type:	Trojan-Downloader
Platform:	W32
Date of Discovery:	September 16, 2006

AutoIt.D, a variant of AutoIt, is a Trojan. AutoIt.D attempts to download and install other malware to the system and changes startup and search pages of Internet Explorer.

Automatic Disinfection

Usually standalone malware (backdoors, worms, trojans, etc.) is automatically removed by F-Secure Anti-Virus (FSAV) starting from version 5.40. Malware files get automatically renamed by FSAV, so they can not be started any more. In some rare cases, when automatic disinfection is not possible, a user can select disinfection action by him/herself to make FSAV rename or delete an infected file. In some special cases it is recommended to use specific disinfection tools provided by F-Secure. They can be downloaded from our ftp site:

ftp://ftp.f-secure.com/anti-virus/tools/

F-Secure Anti-Virus can be purchased from our webshop or from our authorised distributors. A trial version F-Secure Anti-Virus, limited to 30 days, can be downloaded from our website:

http://www.f-secure.com/download-purchase/

All the latest versions of FSAV can download anti-virus database updates automatically. However, these updates can be also downloaded and installed manually from our web or ftp sites:

http://www.f-secure.com/download-purchase/updates.shtml


Manual Disinfection

To manually disinfect standalone malware (backdoors, worms, trojans, etc.) it's usually enough to delete all infected files from a computer and to restart it. Active malware files are usually locked by operating system so different disinfection approaches are required for different operating systems.
Please note that manual disinfection is a risky process, so it is recommended only for advanced users.

If Windows 95, 98 and ME operating system is used, it is recommended to restart a computer from a bootable system diskette and to delete an infected file from command prompt. For example if a malicious file named ABC.EXE is located in Windows folder, it is usually enough to type the following command at command prompt:

DEL C:\WINDOWS\ABC.EXE

and to press Enter. After that an infected file will be gone. If Windows NT, 2000 or XP is used, a malicious file has to be renamed with a different extension (for example .VIR) and then a system has to be restarted. After restart a renamed malicious file will no longer be active and it can be easily deleted manually.


Malware Disinfection Tools

F-Secure provides disinfection tools for certain malware. These tools can be downloaded from this webpage:

http://www.f-secure.com/download-purchase/tools.shtml

ftp://ftp.f-secure.com/anti-virus/tools/


Windows System Restore Issues

If Windows ME or XP is used, it is recommended to disable System Restore feature of these operating systems to prevent a computer from re-infection by an already removed malware. The fact is that System Restore feature of these operating systems might save an infected file into the special folder and copy it back to a hard drive it every time it's been renamed or deleted by F-Secure Anti-Virus or by a user. Instructions on how to disable System Restore feature are here:

Windows ME:
http://www.f-secure.com/v-descs/sfc_dis.shtml

Windows XP:
http://www.f-secure.com/v-descs/sfc_dis1.shtml

It is recommended to re-enable System Restore after disinfection in order to restore stable system configuration in the future, if any crash or incompatibility issue occurs.


Failed Disinfection

In some cases F-Secure Anti-Virus might not disinfect a system automatically. In this case please visit our Support pages:

http://support.f-secure.com/enu/home/virusproblem/howtoclean/

AutoIt.D may arrive on the system as a downloaded file via links that are spammed through Yahoo Messenger.


It may use any of the following message strings:


This is done by searching for the string title "Yahoo! Messenger" in the Windows Title Bar. When the string found, AutoIt.D will secretly and randomly input any of the above messages, every 80 seconds.


The links in the messages direct to script pages that may contain any of the following download sites:



Below is a sample message:



Upon execution, this malware attempts to download another malware file from the following site:



The downloaded file is saved and executed on the victim's machine with the following filename:


This file is detected as IM-Worm.Win32.Sohanad.b.


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



AutoIt.D also changes the Internet Home Page, Yahoo Buzz and Yahoo Launchcast links to the following site:


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:



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