Continuing on from Round 1, I decided to take a step further and show you exactly how susceptible you are to a socially engineered infection through Twitter. Actually it’s more an attack through TinyURL.com, but since Twitter automatically converts URLs in your Tweets (ugh!), it is an attack via Twitter.
For this example, let’s say that a hacker wants to construct a website that references some research on Harvard’s website. It would be on a topic that is of high interest at the moment.
First the hacker (cybercriminal) would use Google Trends (www.google.com/trends) to see what’s hot. As of today (03/02/2009) the list is as follows:
- granville waiters
- nyc doe
- wavy tv 10
- new york city department of education
- dr. seuss birthday
- nyc public school closings
- nyc board of education
- newport news public schools
These are the top 10.
Nothing in there that is really eye catching that covers a broad scope of people. I’ll use dr. seuss birthday.
Our cybercriminal would construct some basic information about how Harvard University has created this research paper detailing the events behind Dr. Seuss stories. Our cybercriminal needs to have something that already indicates some legitimacy and some validation. For this scenario I’m using Harvard University for 2 reasons; they already carry a huge credibility factor and they have a cross-site scripting (XSS) vulnerability that let’s me use their URL for redirection.
The cybercriminal would take the XSS URL and instead of redirecting the reader to another page inside of Harvard’s website, use it to redirect the unsuspecting reader to their malicious website.
Here is the original URL: http://hms.harvard.edu/lshell/WhitePagesdefault.asp?task=staffandfaculty&theurl=
By appending any URL we want to the end of the above string, it will look like we’re sending you to harvard.edu, however, this vulnerability will actually take you somewhere else.
For instance, if I wanted to send you to my website I would use:
Go ahead and click on that and you’ll see what I mean.
Now, that’s not too bad. I if showed you that link in an email or on my Twitter account, you might not see the end of the URL and just click on it to see what Harvard has to say about Dr. Seuss.
But remember that Twitter uses TinyURL.com which converts any long URLs into “tiny” URLs. Plugging that long URL into TinyURL.com’s website it gives me:
With TinyURL.com’s preview function I could see the exact URL of the above TinyURL. Maybe you’d see the redirection at the end and maybe not.
Now, our crafty cybercriminal knows that TinyURL.com has this preview function, so he (we’ll assume a male hacker) converts the URL of his malicious website to one you can’t recognize. This is called URL obfuscation (I love using that word).
This would take my URL of http://www.wewatchyourwebsite.com and convert it to: %68%74%74%70%3a%2f%2f%77%77%77%2e%77%65%77%61%74%63%68%79%6f%75%72%77%65%62%73%69%74%65%2e%63%6f%6d
If you saw this by itself, hopefully you’d be suspicious and avoid the urge to click on it. However, when used at the backend of an already long URL, you might just throw caution into the wind and click away.
Our Harvard URL would become:
Which when converted to a TinyURL.com would result in: http://tinyurl.com/bnq5ej
Go ahead and click on that to see what I mean. As of today, that XSS on Harvard’s site has not been fixed so it will load their frame, but inside will be our home page. Keep in mind that even with TinyURL.com’s preview function, you would only see the obfuscated URL with all the percent signs. This might give you a false sense of security and decide to trust your “gut” and go for it. That’s what the cybercriminal is hoping for.
Obviously our website isn’t going to infect your computer, however, if the redirection URL were to take you to the cybercriminals infectious webpage, you’d be infected and not even know it.
To recap, the purpose of this information is to show you the steps a cybercriminal would follow to use social engineering to spread their malware. They would use Google Trends to find a hot topic, they would use the credibility of some other site, Harvard in this example, they would use obfuscation to hide their work from people who know what to look for and they would use Twitter or some other social networking site to find as many people as they could.
As stated earlier, this isn’t so much a vulnerability of Twitter as it is with TinyURL.com, but since Twitter uses TinyURL.com, it does reflect back on them.
Any comments, questions or remarks? Please post them (unless it’s SPAM).