BruCON 2023 CTF Forensics Challenge

Forensics: Rexer

This is what the challenge says:

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The pattern is the key.

\w*(3).+(T).*([s]).+(g).*([NT]r).*(u).+(L)\w+(Sm).*(N).*}$

asonV3l113UYnrvTfeJpsaeR}ZkJRvA{ThKgr730gnwWhYgVnNTSuhbpJ_BPn7Q8Q7mLnTrc_S3_p3zpFV8Fmm0hrUbvt_24upiqAt7ugXuhbpJ_BPn7Q8Q7mLq8qsSml4Sl4xmw1ON}

\2OREO\9{\8\6\4\4\7\1_\3\5\6\4\4\7\1}

The first pattern selects parts within the string (second line). Then, the third line re-assembles the selected groups to form the flag.

At first, I tried to use ChatGPT to help me out with the regexp. It didn’t work out well and I used Regex101.

This website is very convenient. See on the right how it tells me what are the letters in group \1, those in \2, those in \3 etc.

Then, I had to re-assemble those characters from the 3rd line \2OREO\9{\8\6\4\4\7\1_\3\5\6\4\4\7\1} which gave the flag TOREON{SmuggL3_sTruggL3}.

I liked this challenge.