Posts tagged with "writeup" — Page 3

BackdoorCTF 2017: FUNSIGNALS

September 24, 2017 ❖ Tags: writeup, security, capture-the-flag, binary-exploitation, x86, linux

"funsignals" was a 250 point binary exploitation challenge with 58 solves. The challenge itself was a very trivial example of sigreturn-oriented programming.

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Analyzing Executable Size, part 0 - A Small Proof-of-Concept Loader

July 31, 2017 ❖ Tags: writeup, programming, operating-systems, c, linux

It seems that static linking is back in style, or at least popular among all the hip new programming languages of today. I don't have anything against statically linked binaries, nor do I have a problem with larger executables, but I've noticed that the acceptable size for an executable is a lot larger now than it was a few years ago; that is, the new kids on the block have significantly more leeway than their predecessors. For example - a C program that spits out "hello world" is 7 KB when statically linked to musl. It's 12 KB when dynamically linked to glibc. The same program in D, where the reference compiler doesn't allow dynamic linking to the standard library, is 896 KB. A blog post I read recently about certificate chain verification in Go made a point of praising the toolchain for being able to spit out a binary that was "less than 6 MB!" I'm being more facetious than with my D example, as this was statically linked to an SSL-capable web server, but 6 MB is a little over half the size of a fully-functioning operating system. I'm not so interested in why we settle binaries the size of a few videos, but instead I'd like to look at why they're that large to begin with. To peer in and see what wealth of information is stored inside, and how certain programming languages make use of that information.

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Reverse Engineering Babby's First Archive Format

March 02, 2017 ❖ Tags: writeup, programming, reverse-engineering, video-games, x86, c, python

About two months have passed since the first release of Nekopack - a tool I wrote for extracting game data from Nekopara's XP3 archives. While the process wasn't an amazing reverse-engineering war story that will keep you on the edge of your seat, I feel it deserves a small blog post explaining how I did it. Additionally, there's no real documentation on the XP3 format as far as I'm aware, so hopefully this post will serve as an informal specification.

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