Twitter starts filtering malware URLs
Twitter has begun to filter URLs posted to the short message sharing system in an attempt to reduce Twitters vulnerability to being used as a way of spamming users with malware links and to stop users accidentally spreading bad links. A posting on the F-Secure blog noted that the filtering has been turned on, although Twitter has not announced the new measures officially. Upon entering a message with a link to a known malware site, the Twitter UI rejects the message and displays "Oops! Your tweet contained a URL to a known malware site".
According to ReadWriteWeb, Twitter are not parsing shortened URLs, which may limit the usefulness of this measure. Shortened URLS, such as those from bit.ly or tr.im are popular on Twitter to allow users to pack more content into a tweeted message and work around the 140 character limit. Some shortening services have begun filtering URLs they shorten and will issue a warning if a user attempts to shorten a known bad link.