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[Full-disclosure] Facebook from a hackers perspective

For those interested, here is our latest blog entry.

For the past few years we've (Netragard) been using internet based  
Social Networking tools to hack into our customer's IT  
Infrastructures. This method of attack has been used by hackers since  
the conception of Social Networking Websites, but only recently has it  
caught the attention of the media. As a result of this new exposure  
we've decided to give people a rare glimpse into Facebook from a  
hackers perspective.

Lets start off by talking about the internet and identity. The  
internet is a shapeless world where identities are not only dynamic  
but can't ever be verified with certainty. As a result, its easily  
possible to be one person one moment, then another person the next  
moment. This is particularly true when using internet based social  
networking sites like Facebook (and the rest).

Humans have a natural tendency to trust each other. If one human being  
can provide another human with "something sufficient" then trust is  
earned. That "something sufficient" can be a face to face meeting but  
it doesn't always need to be. Roughly 90% of the people that we've  
targeted and successfully exploited during our social attacks trusted  
us because they thought we worked for the same company as them.

The setup...

Facebook allows its users to search for other users by keyword. Many  
facebook users include their place of employment in their profile.  
Some companies even have facebook groups that only employees or  
contractors are allowed to become members of. So step one is to  
perform reconnaissance against those facebook using employees. This  
can be done with facebook, or with reconnaissance tools like Maltego  
and pipl.com.

Reconnaissance is the military term for the collection of intelligence  
about an enemy prior to attacking the enemy. With regards to hacking,  
reconnaissance can be performed against social targets (facebook,  
myspace, etc) and technology targets (servers, firewalls, routers,  
etc). Because our preferred method of attacking employees through  
facebook is via phishing we normally perform reconnaissance against  
both vectors.

When setting up for the ideal attack two things are nice to have but  
only one is required. The first is the discovery of some sort of Cross- 
site Scripting vulnerability (or something else useful) in our  
customers website (or one of their servers). The vulnerability is the  
component that is not required, but is a nice to have (we can set up  
our own fake server if we need to). The second component is the  
required component, and that is the discovery of facebook profiles for  
employees that work for our customer (other social networking sites  
work just as well).

In one of our recent engagements we performed detailed social and  
technical reconnaissance. The social reconnaissance enabled us to  
identify 1402 employees 906 of which used facebook. We didn't read all  
906 profiles but we did read around 200 which gave us sufficient  
information to create a fake employee profile. The technical  
reconnaissance identified various vulnerabilities one of which was the  
Cross-site Scripting vulnerability that we usually hope to find. In  
this case the vulnerability existed in our customer's corporate website.

Cross-site scripting ("XSS") is a kind of computer security  
vulnerability that is most frequently discovered in websites that do  
not have sufficient input validation or data validation capabilities.  
XSS vulnerabilities allow an attacker to inject code into a website  
that is viewed by other users. This injection can be done sever side  
by saving the injected code on the server (in a forum, blog, etc) or  
it can be done client side by injecting the code into a specially  
crafted URL that can be delivered to a victim.

During our recent engagement we used a client side attack as opposed  
to a server side attack . We chose the client side attack because it  
enabled us to select only the users that we are interested in  
attacking. Server side attacks are not as surgical and usually affect  
any user who views the compromised server page.

The payload that we created was designed to render a legitimate  
looking https secured web page that appeared to be a component of our  
customer's web site. When a victim clicks on the specially crafted  
link the payload is executed and the fake web page is rendered. In  
this case our fake web page was an alert that warned users that their  
accounts may have been compromised and that they should verify their  
credentials by entering them into the form provided. When the users  
credentials are entered the form submitted them to http://www.netragard.com 
  and were extracted by an automated tool that we created.

After the payload was created and tested we started the process of  
building an easy to trust facebook profile. Because most of the  
targeted employees were male between the ages of 20 and 40 we decided  
that it would be best to become a very attractive 28 year old female.  
We found a fitting photograph by searching google images and used that  
photograph for our fake Facebook profile. We also populated the  
profile with information about our experiences at work by using  
combined stories that we collected from real employee facebook profiles.

Upon completion we joined the group that our customer's facebook  
group. Joining wasn't an issue and our request was approved in a  
matter of hours. Within twenty minutes of being accepted as group  
members, legitimate customer employees began requesting our  
friendship. In addition to inbound requests we made hundreds of  
outbound requests. Our friends list grew very quickly and included  
managers, executives, secretaries, interns, and even contractors.

After having collected a few hundred friends, we began chatting. Our  
conversations were based on work related issues that we were able to  
collect from legitimate employee profiles.  After a period of three  
days of conversing and sharing links, we posted our specially crafted  
link to our facebook profile. The title of the link was "Omitted have  
you seen this I think we got hacked!" Sure enough, people started  
clicking on the link and verifying their credentials.

Ironically, the first set of credentials that we got belonged to the  
person that hired us in the first place.  We used those credentials to  
access the web-vpn which in turn gave us access to the network. As it  
turns out those credentials also allowed us to access the majority of  
systems on the network including the Active Directory server, the  
mainframe, pump control systems, the checkpoint firewall console, etc.  
It was game over, the Facebook hack worked yet again.

During testing we did evaluate the customer's entire infrastructure,  
but the results of the evaluation have been left out of this post for  
clarity. We also provided our customer with a solution that was unique  
to them to counter the Social Network threat. They've since  
implemented the solution and have reported on 4 other social  
penetration attempts since early 2008. The threat that Social Networks  
bring to the table affects every business and the described method of  
attack has an extraordinarily high success rate.

Please leave your comments on the blog.



        Adriel T. Desautels
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