trashtalker is a pwnable/"leakable" CTF challenge built for the CrikeyCon 2016 CTF
It also featured in the BSides Canberra 2016 CTF with a different flag, but otherwise identical code.
The file I'm giving you contains a placeholder flag that looks like not_the_flag{something}.
The server is running the same binary, but with a real flag that looks like flag{something}.
trashtalker is protected by a proof-of-work challenge. Challenges look like n:s. You should respond with a string that, when appended to s, results in a string that has a SHA256 hash that starts with n "0" characters (when the hash is represented as a hex digest). Hashes are calculated without trailing newlines, and you should only send a winning suffix (not the whole string)
Obtain the server's flag, get the points.
Bet you can't.
trashtalker- distributable binary with the fake flag. This file was given to contestants.trashtalker_priv- undistributable binary with the real flag, for running on the challenge server (e.g. via xinetd). This file was kept secret.
Have you published a writeup? Message me somehow (e.g. I'm @justinsteven on Twitter) and I'll add it here!
@mongobug pointed out that I failed to filter for some memory-corrupting format string sequences (using hn and hhn). The binary is vulnerable to remote memory corruption, and possibly RCE. Do not publicly expose it on a machine you care about.
trashtalker is licensed under Apache License 2.0 (see LICENSE)
Pre-built binaries include software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (http://www.openssl.org/) (see openssl-license.txt)