RWTH-CTF 2011 mysocksd

The vulnerability

The mysocksd binary is a SOCKS5 proxy written in C++. The binary is vulnerable
to an integer overflow when using SOCKS5’s feature of connecting to a remote
host by specifying a domain name. The domain name length is specified using a
single byte which gets overflown when set to ‘\xff’. This in turn leads to a
heap overflow. So, suspecting a classic unlink attack, we first check where it
crashes. :-)
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