GCHQ Can You Crack It 2011

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GCHQ Can You Crack It 2011 (Stage 1)

The three stages within the challenge are designed so that participants can demonstrate the basics of analysing shellcode and obfuscation mechanisms, reverse engineering of malicious binary code and vulnerability analysis. These techniques are fundamental skills for a cyber security specialist at GCHQ

This starts with the main image on the canyoucrackit.co.uk site. To solve this stage it is necessary to identify that this is code that can be run by an Intel x86 compatible processor. After analysis, it is clear that this machine code implements the RC4 decryption algorithm, and is able to decrypt a block of data that is hidden inside the PNG file, in a comment tag. Once decrypted, this data reveals the location of stage 2 of the challenge.

www.canyoucrackit.co.uk

Solved by

Dr Gareth Owen

School of Engineering

University of Greenwich

Click on Image for more information.

Relocated

Senior Lecturer

School of Computing

University of Portsmouth

Can You Crack It Stage 1 Part 1

Can You Crack It Stage 1 Part 2

GCHQ Can You Crack It 2011 (Stage 2)

This is a JavaScript programming challenge, with a cyber security angle. To solve this stage an implementation of a simple virtual processor is required. Some notes on the architecture are provided along with a block of data that can be analysed. Solving this stage will reveal the final stage of the challenge.

Can You Crack It Stage 2

GCHQ Can You Crack It 2011 (Stage 3)

The final stage is a reverse engineering challenge. An executable file can be downloaded from the location revealed in stage 2. This executable parses a license file - if it gets given a correct input, the challenge is revealed to be over, and a link to the 'success' page is provided to the participant.

We included a number of ways that this stage could be solved, as we are interested to see how people would attack the problem - coming up with innovative solutions to seemingly impossible problems is the day job at GCHQ. For example, there has been some comment by security experts on the fscanf buffer overflow that we included in this executable - one option to solving the problem would be to use this overflow to skip over certain checks in the executable. Other alternatives for this stage involved breaking the weak crypt, patching the executable directly to bypass the check, or analysing the assembly instructions and realising that this was all a complete diversion.

Can You Crack It Stage 3

GCHQ Can You Crack It 2011 (Craked)

This website address will revel the Key:

Pr0t3ct!on#cyber_security@12*12.2011+

Enter Keyword at http://www.canyoucrackit.co.uk click submit.

You will then be redirected to URL:

http://www.canyoucrackit.co.uk/soyoudidit.asp

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