Remnant Hack That Checksum Competition

The place to start, or join, a competition/contest.
Post Reply
User avatar
Grimdoomer
Admin
Posts: 1835
Joined: Sun Dec 09, 2007 9:09 pm

Remnant Hack That Checksum Competition

Post by Grimdoomer »

Ok this is something I have been tossing around for a week or two, and decided to put it into action. I think this will get absolutly no where, but it's worth a try.

How this Works
For the first few contests, I will create the format and app for you guys. Basically, you will recive an app to check/create files, and you must reverse engineer it to figure out how the checksum works. This should help some of you learn about cryptography and encryption.

Rules
  • No Illegal Content.
    No Private key Cryptography, AES is fine because you need the key in the assembly. If you want to use RSA, you must hardcode the key.
    The Check app must be able to create new files in your format.
    No Remote code, ex server side scripts.
    If you forget to obfuscate your app, the contest will be restarted with a new app.
    The winner of each will get something, I don't know what, maybe an emblem when those get fixed.
    When posting the checksum details, please provide a coded method on how to recalculate it.
Suggestions
  • Obfuscate your check app.
    Use crypto and custom encryption.
    I have one thing over all of you, which is some assembly skills, so get creative.
The App
Here is the first app. It creates a file with my own format, using a jpeg file. It has a piss easy checksum, so this should prove easy to some of you.
Attachments
Check App.rar
App
(205.03 KiB) Downloaded 484 times
Don't snort the magic, we need it for the network.
User avatar
troymac1ure
Keeper of Entity
Posts: 1282
Joined: Sat Aug 09, 2008 4:16 am
Location: British Columbia, Canada, eh
Contact:

Re: Remnant Hack That Checksum Competition

Post by troymac1ure »

The majority of the time the program creates 'corrupt files'. Actually it stores no checksum whatsoever. Also, I believe you are leaving the file open as the output file is also locked until the program is closed.
User avatar
Grimdoomer
Admin
Posts: 1835
Joined: Sun Dec 09, 2007 9:09 pm

Re: Remnant Hack That Checksum Competition

Post by Grimdoomer »

troymac1ure wrote:The majority of the time the program creates 'corrupt files'. Actually it stores no checksum whatsoever. Also, I believe you are leaving the file open as the output file is also locked until the program is closed.
I forgot to close the binary writer. I hate that so much. Any way I fixed the download and it does infact create a checksum.
Don't snort the magic, we need it for the network.
User avatar
troymac1ure
Keeper of Entity
Posts: 1282
Joined: Sat Aug 09, 2008 4:16 am
Location: British Columbia, Canada, eh
Contact:

Re: Remnant Hack That Checksum Competition

Post by troymac1ure »

Just wondering if you are able to do your own. I know assembly as well, but the program you used afterwards, EZIRIZ .NET Rector looks to be a very secure program. Not sure if this is the greatest "learning" tool.

If so, what disassembler do you use that would give you anything back?
User avatar
Grimdoomer
Admin
Posts: 1835
Joined: Sun Dec 09, 2007 9:09 pm

Re: Remnant Hack That Checksum Competition

Post by Grimdoomer »

troymac1ure wrote:Just wondering if you are able to do your own. I know assembly as well, but the program you used afterwards, EZIRIZ .NET Rector looks to be a very secure program. Not sure if this is the greatest "learning" tool.

If so, what disassembler do you use that would give you anything back?
IDA might.
Don't snort the magic, we need it for the network.
Post Reply