Friendly exploits

If you happen to be friends with me on Facebook you will have seen a bunch of rather strange updates from me last night. This all started with a tweet (that was also sent to Facebook) by a friend who joked about doing something with the <MARQUEE> tag (see for an example of it and similar things). I saw the joke, as I was reading it through Gwibber or the Facebook website. However…. Leah saw text scrolling over the screen… just like the <MARQUEE> tag actually did.

She was looking at it on her iPad using an app called Friendly.

So I immediately posted a status update: “<script lang=”javascript”>alert(“pwned”);</script>”. This is a nice standard little test to see if you’ve managed to inject code into a web site. If this pops up a dialog box, you’ve made it.

It didn’t work. It didn’t display anything… as if it was just not running the script tag. Disappointing. I soooo wanted it to break here.

I did manage to do all sorts of other things in the Live Feed view though. I could use just about any other HTML tag… including forms. I couldn’t get a HTTP request to my server out of a HTML form in the Live Feed view… but once we did manage to crash Friendly (enough that it had to be force quit on the iPad).

I posted a photo of me holding up the iPad to my laptop web cam to show off the basics:

And then one of what happened when I tried a HTML form (this wasn’t reproducible though… so kind of disappointing):

What we did notice however was that HTML tags were parsed in comments on images too…. which made me wonder… It’s pretty easy to make a HTML form button that will do something… so I posted the same image again with a button that would say “Next” but would take you to a web page on one of my servers instead. It worked! I got a HTTP request! Neat! I could then present a HTML page that looked legit and do the standard things that one does to steal off you.

But I wonder if scripts would work…. so I posted:

Photos are proving more exploitable.... <script lang="javascript">alert("pwned");</script>

and then clicked on the image on the iPad……


I could from here do anything I wanted.

Next… I should probably report this to the developers…. or steal from my friends and make them post things to facebook implying improper relationships and general things that would get you fired.

I went with the former… but the latter would have been fairly easy as the Facebook page for the app nicely tells me which of my friends use it. I could even target my attack!

So I sent a warning message to friends (the 18 of them who use the Friendly app), sent a “contact the developer” message to the developers, sent out a warning on Twitter and went to bed.

Got an email overnight back from the developer: “We just pushed a server update that solves this issue.”

Now… in my tcpdump while trying some of the earlier things I was just seeing https requests to facebook API servers from the iPad, but I don’t thing I looked too closely at images. I have no idea if they’ve actually fixed the holes and I don’t have an iPad to test it on. If you do, go try it.