Shortened URLs

Most tweets, and tots of other electronic messages, include links that have been shortened by services such as Bit.ly, Tr.im, and Googl. The URL aliases are handy, hut they pose a risk, too: Since short URLs give no bint of the destination, attackers can exploit them to send you to malicious sites.

Use a Twitter client: Programs such as TweetDeekinclude options in their settings to display previews of shortened URLs. With such a setting enabled, clicking a shortened URL within a tweet brings up a screen that shows the destination page's title, as well as its full-length URL and a tally of how many other people have clicked that link. With this information at your disposal, you can make an ill-formed decision about whether to click through and visit the actual site.

Install a URL-preview plug-in: Several Web browser plug-ins and services per- form a similar preview function. When you create a shortened address with the TinyURL service, for instance, you can choose an option to create a preview version so that recipients can see where it goes before clicking. Conversely, if you're considering visiting a TinyURL link, you can enable its preview service (tinyurl.com/preview.php) to see the complete URL. For the TinyURL previews to work, though, you must have cookies enabled in your browser.

ExpandMyURL (expandmyurl.com) and LangURLPlease (www.longurlplease.com) both provide Web browser plug-ins or applets that will verify the safety of the Ml URLs behind abbreviated links from all the major URL-shortening services. Rather than changing the shortened links to their full URLs, however, ExpandMyURL checks destination sites m the background and marks the short URLs green if they are safe.

Googl, Google's URL-shortening service, provides security by automatically scanning the destination URL to detect and identify malicious Websites, and by warning users when the shortened URL might be a security concern. Unfortunately, Googl. has limited application because it works only through other Google products and services.