JS.Fortnight travels via email, embedded and hidden in the body or signature of HTML-rendered email. Any email sent after infection will carry the same hidden code, in turn infecting friends, family, and co-workers, hijacking their browsers and pointing it to a wide array of adult web sites.
Though Microsoft patched the vulnerability exploited by the worm in October 2000, antivirus vendors are reporting increasing numbers of incidents, suggesting many have not applied the necessary update. All users of Internet Explorer versions 4.x or IE 5.x, who have not previously installed the patch, are vulnerable to JS.Fortnight.
The Fortnight worm is not the first to spread via email without the use of an attachment, nor is it the first worm to exploit the Microsoft VM vulnerability. Despite a precedent for exploitation, user reluctance or the lack of understanding about the need to patch these vulnerabilities leaves users vulnerable to this and other attacks. Keeping antivirus software updated is crucial. However, with new variants of Fortnight appearing on a regular basis, additional steps are needed to prevent against these threats. Paying regular visits to the Windows Update Center to keep patches current and following the steps outlined in Securing Internet Explorer and the Email Help Center will protect against threats such as JS.Fortnight, saving you - and your family - from the discomfort caused by this worm.
