I used Fiddler to sniff traffic between iPad 2 and Jailbreakme during jailbreaki...

JonnieCache · on July 6, 2011

There is no PDF file, the pdf is a base64 encoded data-uri in the javascript, in the page itself, not even in a separate asset.

For those who fancy doing some analysis, here's the curl command with the required ipad UA string:

    curl -A "Mozilla/5.0 (iPad; U; CPU OS 4_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8F190 Safari/6533.18.5" http://www.jailbreakme.com

EDIT: here's the b64 pdf: http://pastebin.com/69tnPMdV

the PDF is very invalid, because it never needs to masquerade as a real document, it doesn't have to pretend to implement the PDF spec correctly. This makes it somewhat resistant to analysis, it doesn't even have the required '%%EOF' marker so many tools choke on it immediately.

EDIT: There's an unterminated stream object in there which doesn't have a type, and it also has a declared length of 61 bytes and an actual length of well over 400. I think we have a winner... Unfortunately iOS shellcode analysis is waaaay over my head so I'll have to do something useful instead.

gary4gar · on July 6, 2011

I decoded base64 & got this: https://gist.github.com/1067129

bunch of random gibberish?

kristofferR · on July 6, 2011

When decoding to ASCII instead of UTF-8 (like you've done) I got this. It makes a little bit more sense at least, but not much.

http://pastebin.com/YuPrMhiE

gary4gar · on July 6, 2011

I guess the actual shell code starts from line 40 ">>stream..."

It must be using some other encoding, only if we knew which!

GHFigs · on July 6, 2011

It's a PDF FlateDecode block, i.e. it's DEFLATEd. The actual payload within may be different, but this much has been used before.

http://digdog.tumblr.com/post/894317027/jailbreak-with-pdf-f...

JonnieCache · on July 6, 2011

It's presumably just a lump of binary ARM opcodes.

demonfly · on July 6, 2011

We need a debugger or a disassmbler like IDA Pro to make reverse engineering of that code

comex · on July 6, 2011

It's compressed with FlateDecode; if you decompress it you can see the embedded .pfb, which has the actual exploit.

demonfly · on July 6, 2011

thank you comex, I did not actually found how to decompress it, I keep trying with pdf-parser with no luck

demonfly · on July 7, 2011

I've succesfully extraced the font with pdf-parser with this command: "python pdf-parser.py --object 4 --filter --raw pdfexploit.pdf > font.pfb" everything is documented here http://www.bufferoverflow.it/2011/07/06/jailbreakme-ecco-com...

mrspeaker · on July 6, 2011

Is there a way to decompile the base64 code into the actual script? I'm guessing the shellcode is the bits after the AAAAAAA's?

kristofferR · on July 6, 2011

http://pastebin.com/YuPrMhiE

It doesn't make that much more sense to me, but atleast you can see some commands.