Challenge Context#

big brother was a 500-point reverse-engineering challenge. The final session notes record the flag as submitted and accepted.

Evidence Preserved#

The local detailed reverse-engineering notes for this challenge were not retained in the workspace, but the solving session recorded the accepted flag:

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big brother: leet{Gh4_r3S5et1w_se551oNs_34wtAN1_mSG_0pp0} — 500pts, submitted

Core Idea#

The flag text points to the intended behavior: reset or recover session/message state (r3S5et1w_se551oNs, mSG). The challenge likely hid the flag behind program state or session logic rather than a raw printable string.

A publish-quality version of this writeup needs the original reversing notes rebuilt from the binary in:

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/home/lain/ctf/1337-local/challenges/rev/big-brother/

Flag#

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leet{Gh4_r3S5et1w_se551oNs_34wtAN1_mSG_0pp0}

Lesson Learned#

Save the reverse-engineering trail as soon as the flag is accepted: tool output, offsets, decryption routine, and why the candidate was correct. The accepted flag alone is enough for an archive, but not enough for a strong public writeup.

Cover: Wallhaven qrjew7.