F-Secure Virus Descriptions : SillyDownloader

Summary

SillyDownloader is a family of simple script trojan downloaders written with JavaScript or Visual Basic Script languages. These downloader use various vulnerabilities in Internet Explorer to download and execute other malware.

Detailed Description

This family of downloaders use XMLHTTP control to download and ADODB.Stream control to write malware on the vulnearble machine, often combined with some other vulnerabilty that allows the downloader to escape from the Internet Explorer internet zone.

Typically SillyDownloader replaces the Windows Media Player in order to make sure that the downloaded component gets executed.

The downloaded component usually contains an another trojan or a backdoor.

Further information about ADODB control is available from Microsoft at: http://support.microsoft.com/?kbid=870669

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Write-up: Sami Rautiainen, July 13th, 2005;

F-Secure Corporation