Codehead's Corner
Random ramblings on hacking, coding, fighting with infrastructure and general tech
Posted: 13 Jan 2018 by Codehead
5 minute read


Command Files allow you to start up gdb in a way that saves you typing the same commands over and over, even doing some of the ‘driving’ for you. I’m not suggesting that this is the best way to use gdb but I found it really helpful and I saved a bunch of time. I’m blogging it for my own reference and to help others find a lesser known, but very useful feature of the tool.


While working on the SLAE64 course assessments, I found myself jumping in and out of gdb a lot. Constantly rebuilding and refining my shellcode test binaries meant that I ended up in constant cycle of doing a whole heap of setup in gdb to get things the way I wanted them, only to spend a few seconds debugging the target, then quitting, tweaking the code, rebuilding and repeating the whole process again.

I’m not a great typist, but I keyed in this sequence so many times that I could probably do it in my sleep:

layout asm
layout reg
break _start

There has to be a better way.

Categories: linux assembler hacking
Posted: 21 Aug 2016 by Codehead
12 minute read

The LabyREnth competition ran from 15th July to 14th Aug. I only managed to find time to do the first Windows challenge. It was a tricky one and I was only able to work at it in fits and starts, often with days or weeks between sessions. However, I learnt quite a few handy new things while working on it, so I’m writing this as a reference for myself and as an example of the dead-ends and rabbit holes of the analysis process for those who are interested.

Categories: Hacking CTF
Posted: 21 Feb 2016 by Codehead
3 minute read


File Checker (rev60)


My friend sent me this file. He told that if I manage to reverse it, I’ll have access to all his devices. My misfortune that I don’t know anything about reversing :/

Categories: Hacking CTF
Posted: 7 Feb 2016 by Codehead
3 minute read

I hadn’t played SharifCTF before, but these guys put on a good competition.

Unfortunately I had other commitments, but I managed to spend a little bit of time looking at some of the challenges.

dMd was a reverse engineering challenge worth 50 points. A binary was provided with the description:

Flag is : The valid input.

file told me that the binary was an x86-64 ELF, so I threw it at my Fedora install and pulled up the disassembly in IDA.

Categories: CTF Hacking
Posted: 7 Feb 2016 by Codehead
2 minute read

SRM was another 50 point reverse engineering challenge at SharifCTF 2016. A binary was provided with the following description:

The flag is : The valid serial number.

file reported that the binary was a PE32 for Windows. So I fired up a Win7 VM and pulled up the disassembly in IDA.

Running the binary resulted in a dialog asking for an email address and a serial number.

RM Initial Screen

Categories: CTF Hacking
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