Disconnect3d's Security Blog: low level security, CTF writeups and others
This blog post is a write up of an “Upload Server” challenge where we had to hack a simple server written in Python and steal a secret file (flag) from it. The task is from the Insomni’hack CTF 2025 competition that I played with my team, justCatTheFish in Lausanne, Switzerland. We scored 4th place (or 5th overall, though academic teams had separate ranking). Below you can see how it looked like…
When we think of a null pointer, NULL in C or nullptr in C++, we typically assume it is “invalid” or “not pointing to a valid memory location”. But what if I tell you that a null pointer can actually point to valid memory under certain conditions? In this post, we will see this on Linux.
A friend of mine had an interesting case recently where they wanted to debug an already running Python script on Linux and after some testing it turned out this is possible, so let’s see how it can be done in CPython :).
I gave a talk on “Python specialized bytecode” on Pykonik #70 where I also made a walkthrough over the “pycjail returns” challenge from ångstrom CTF 2024. The video can be found here and its slides here.
Some time ago during an audit I found an out-of-bounds bug that was not detected by AddressSanitizer. This spawned a whole research at Trail of Bits which I talked and wrote about in details!
This blog post is a report of the two coding sprints for the Pwndbg project that I organized first on the EuroPython 2022 conference and then, taking inspiration from the previous one, in the Hackerspace Kraków, located in Cracow, Poland.
TLDR: The man inet_aton states that “inet_aton() returns nonzero if the address is valid, zero if not” …and so it is sometimes used to check if a string is a valid IP address. Which should be fine, but isn’t, because some implementations are weird.
I have written a blog post about checking if a mutex is locked in Go. It can be found at https://blog.trailofbits.com/2020/06/09/how-to-check-if-a-mutex-is-locked-in-go/.
I haven’t written any post in here for some time and I want to fix that. For now, it is probably worth mentioning that in the meantime I gave many talks, reviewed some articles in Paged Out! and wrote two articles: A blog post on Trail of Bits blog: “Understanding Docker container escapes” An article “from cpython_exploit_ellipsis import *” to Paged Out! #01
I came back from a PUT Security Day where I gave a talk about Docker security. One of the questions I asked myself when preparing the talk is whether one can reboot their PC (aka host machine) from a docker container.