Sites like Tinyurl.com and Bitly.com are the go-to places for Tweeters who do not want long URLs to eat up their typing space. However, shortened URLs have a second, more insidious use. They allow spammers and hackers past the old email filters and into your inbox.
Most email anti-spam engines were created before the use of embedded URLs in emails, not to mention shortened ones. Most anti-spam programs try to trace back the URL to see if the site is dangerous. However, a shortened URL can be used by hackers two ways.
The first way is simple. They plug the site they want you to get directed to into one of the known and trusted URL shortening sites available for free to the public. Because the URL shortening site is trusted, the link is trusted. However, the link does not take you to the URL shortening site; it takes you where it was originally directed.
Secondly, hackers get even more creative. Once the anti-spam filters get around the URL shortening sites, as some have done, hackers create their own URL shortening sites. Essentially, they shorten a site that’s already shortened. So, when you click on the link, you get redirected not once, but twice. The first redirection is safe, the next is a hackers.
This was “yet another example” of cyber-criminals adopting new technology to bypass traditional security measures, said Bradley Anstis, vice-president of technical strategy at M86.
“A lot of the traditional anti-spam engines were developed before Twitter, so they are not geared up to recognize embedded URLs as seen in blended email threats in spam, let alone shortened URLs that link to malicious, or compromised Web pages,” Anstis said.
Some frightening statistics:
In May 2011, the global ratio of spam in email traffic from new and previously unknown bad sources increased by 2.9 percentage points since April 2011 to 75.8% (1 in 1.32 emails).
The global ratio of email-borne viruses in email traffic from new and previously unknown bad sources was one in 222.3 emails (0.450 percent) in May, a decrease of 0.143 percentage points since April. (From Net-security.org)
So, what can you do to protect yourself? For one, never click on an email link if you do not trust the sender. Two, even if you do trust the sender, try to get to the link organically, meaning follow the normal method. If you are checking on a shipment, go through the main website instead of clicking on the link. These simple tricks will help to keep your computer and information safe from hackers.
This Guest post is by Christine Kane from internet service providers. She is a graduate of Communication and Journalism. She enjoys writing about a wide-variety of subjects for different blogs. She can be reached via email at: Christi.Kane00 @ gmail.com.
Here’s a super tip from anarchy4ever – “Some people may call me paranoid but I NEVER click on shortened url links. People should use url enlarger sites such as this one:
Just a personal observation – anarchy4ever is far from being paranoid – sounds like a very sensible solution.