Monthly Archives October 2015

Very quick challenge this one, solved in one line shell script. Here's the clue: The ZIP file contains a Python script called "shiftcrypt.py". The meat is this part: result = [] blocks = struct.unpack("I" * (len(data) / 4), data) print repr(blocks) for block in blocks: result += [block ^ block >> 16] The first thing I thought here is, this…

I don't mind admitting that Hitcon was HARD. Possibly some of the hardest challenges I've faced CTFing so far. Or maybe I was just rusty. Anyway here's one challenge I found particularly rewarding from Hitcon 2015. The clue was fairly cryptic, not giving anything away. It simply delivered a compressed tarball... When extracting the tarball we are rewarded with two…

I didn't have any time to play D-CTF this year because im out of the country traveling. I did spend one evening solving these two challenges though because I thought of an interesting idea I could apply to both challenges simultaneously. Basically we are given two Linux ELF binaries: https://github.com/ByteBandits/writeups/blob/master/defcamp-quals-2015/reverse/r100/r100.bin https://github.com/ByteBandits/writeups/blob/master/defcamp-quals-2015/reverse/r200/r200.bin Each of these binaries is a 64  bit ELF…

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