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jackyyll
Expert Cheater
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 Posted: Wed Aug 06, 2008 5:08 pm Post subject: Re: RE: |
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| Ksbunker wrote: | Reversing packet formats can be a labour intensive with plenty of trial and error and process of elimination.
I wrote a tute not too long ago about reversing a packet in a game I occasionally play;
http://ksbunker.beyondgaming.org/tutorials/roguespear-tutorial.txt
It should go w/o saying but, different games use different formats, timestamps, checksums, etc... so there is no single generic method of reversing packets.
The best way to understanding how a packet works it to attempting to change only one variable at a time within a packet. Much in the same way scientific based experiments attempt constrain all parameters with exception to one to see if the intervention had any effect on x.
So I would recommend working with a text packet and send the same text packet over and over and records the results. If the packets are not the same, you know that there's at least, some form of timestamp. If the packets are the same, you know no timestamp exists, but that does not eliminate a potential checksum.
To determine if a checksum exists, send the same text again HOWEVER change one character of text (same size as before). If only 1 byte has change (ie. the actual letter that was changed), you know there is no checksum. IF the text was checksumed, a single letter edit would grossly alter the configuration and format of a particular aspect of the packet.
In case there is not checksum or timestamp, yourt job is made a lot easier; send and record more text packets of the same length that you originally recorded. If the test was 5 chars, send a 4 character text (different text though), and check to see if there's 5 bytes chains different anywhere. If you find something gj.
If not, try the same text, but use 4 characters (and remove the last character), that way the packet should fundamentally be the same, except for the sizeof string byte (if any existed), but also check to see if the first 4 bytes of the 5 char string were the same in the packet as the first 4 bytes of the 4 char string.
Anyway, i've probably lost you, but it's just some ideas to play with.
As for debugging and tracing back through the code for encryption routines, it can be handy to set a BPM on send. There may be various calls to send from within the code, with WPE you know the data you're looking for so just BP each Send() call and locate the one(s) sending the data you're after.
Once found, using the call stack, just trace back through the calls untill you find something interesting. May also benefit to look in the stack for a pointer to the string that you typed. If you can find the plain text, follow the function, it surely must lead to the encrypt func, and you know you're close.
But yeah, play around. |
Have to say, it's a very good tutorial hehe. I used it to crack my first packet encryption on some other game. |
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CRISISxCupid
I post too much
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Joined: 09 Jun 2007
Posts: 2256
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| Posted: Thu Aug 07, 2008 8:25 am Post subject: |
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| crayzbeef wrote: | | iNcorrection wrote: | | So ASM? |
If you're asking that you obviously don't know shit about programming and definitly nothing about packet encryption/decryption. |
Thanks for the fucking update. LEAVE NOW. I was already helped and you still replied. Idiot. CLOSE PLEASE. |
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atom0s
Moderator
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Joined: 25 Jan 2006
Posts: 8588
Location: 127.0.0.1
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| Posted: Thu Aug 07, 2008 6:50 pm Post subject: |
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Closed due to request. No need to flame either..
_________________
- Retired. |
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