"According to Finjan Software, which has just released its latest Web trends report, caching technology used by search engines, ISPs and large companies has been discovered to harbour certain kinds of malicious code even after the website that hosted it has been taken down.

Such "infection-by-proxy" code can remain in caches for as long as two weeks, giving it a "life after death" at a time it would conventionally be assumed to have been neutralised. Although caching does not always save copies of everything on a website, it will still store code embedded in html, including programming formats such as Javascript. "

Article Link: http://www.techworld.com/security/news/index.cfm?newsID=7083&pagtype=all