Category :


Type :


Aliases :

Delude, Trojan.BAT.Startpage.a, QHosts-1, QHosts-1.dr


Delude is a trojan that is available on a web page. The web page contains a code that uses a vulnerability in the Internet Explorer (MS03-032) to execute.

More information about the vulnerability is available from Microsoft at:

This vulnerability as well as some others has been fixed within October 2003 Cumulative Patch for Internet Explorer available at:


Based on the settings of your F-Secure security program, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details


The HTA code available on a web page downloads a file "partyboy.exe" from an ftp site and runs it. This file is is packed with UPX. It is a batch file which was compiled to executable binary (".exe") using a BatToExe tool.

When executed, it changes the Internet Explorer start page to It prevents access to the most major search engines such as Google, Yahoo, Lycos, MSN and AltaVista. To do this it replaces the following file:

  • %windir%\system32\drivers\etc\hosts

where %windir% is the Windows installation directory.


This new variant is similar to Delude.A, but it uses a file AOLFIX.EXE instead of Partyboy.exe and it changes the name server address from the registry, causing that the DNS requests are directed onto wrong host. The IP address of this host is

The change is made via a registry file ("o.reg") that is dropped into Windows installation directory, and executed. Additionally it will replace the hosts file similar way like Delude.A, while the content of the replaced hosts file is different.

Delude.B changes the start page to Google search engine.

In addition Delude.B checks is the operating system Windows NT, 2000 or XP. In this case it will drop and execute another registry file ("o2.reg") as well as a script ("o.vbs"). These attempt to make sure that the name server changes have been applied to the system.

The changes made to the Windows DNS settings can be seen and restored from the TCP/IP properties.

All registry and script files that Delude.B drops are deleted after execution.

At the time of writing this description the above mentioned patch MS03-032 does not fix the vulnerability that Delude uses.


This variant is a modification of the Delude.B. It is otherwise functionally identical, but it uses two nameservers - and