For this challenge we were given a corrupted git repository. We started by checking out the git repository (using git clone) and checking the consistency of the repository (using git fsck):
Checking object directories: 100% (256/256), done. error: sha1 mismatch 354ebf392533dce06174f9c8c093036c138935f3 error: 354ebf392533dce06174f9c8c093036c138935f3: object corrupt or missing error: sha1 …read more
We received a PNG file that got somehow corrupted in transit. Reading the PNG specification and looking at the first couple of bytes in the header we saw that an 0x0d byte was dropped. The file used 89 50 4e 47 0a 1a 0a as header instead of 89 50 …
read moreWe are told that there's a treasure waiting at treasure.ctf.0ops.sjtu.cn so we have to start digging!
Firing up dig: dig treasure.ctf.0ops.sjtu.cn -t ANY tells us that the target is a IPv6 address.
Let's do a traceroute to that address:
$ traceroute6 treasure.ctf …read more
Another lazy Sunday (oh well, actually I should be writing papers and grant proposals but we are not talking about that right now) and I'm scrolling through my email when I stumbled upon a "FedEx notice" with your usual "you have not picked up your package" scam and I figured …
read moreThis year marked my 11th year of congress (and 10th visit with a short hiatus in 2012). Just like all the years before we headed to the conference location a day before the start of the 31c3. After arriving in Hamburg (after a quick detour through …
We received a file that looked like it was compressed. Let's just pipe it through xz and see what it really is. Aaah, looks like some old and obscure machine code of a machine that has long since been retired.
The machine code is of the CDC 6600, a very …
read moreAt OSDI'14 we published our paper on [1] where we introduce two new security properties that protect programs against control-flow hijack attacks enabled by memory corruption vulnerabilities. The design space in this area is already very cluttered and we use this blog post to highlight the differences between the individual …
read moreAs part of the weekly CTF meetings we discussed some basic stack-based, heap-based, and format string based exploits. For system security challenges these are bread and butter techniques and rely on a huge amount of pre-existing knowledge about operating systems, kernels, process creation, dynamic loading, C programming, stack layouts, and …
read moreDo you know this situation where you have some domain specific knowledge about a problem but first level support at a company blocks you from getting to a knowledgeable person? An example would be tech support at an internet company where you have already restarted your modem and computer yet …
read moreWriting scientific conference or journal papers is an art by itself. This article is not about writing great papers as there already are many good articles that focus on paper writing itself and cover technical aspects, structural aspects, or writing style aspects. In this article I want to give an …
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