This time we’ve got a simple pwn challenge, an unprotected binary, so I’d say it’s an easy one. Multiple vulnerabilities intertwine, waiting to be uncovered. Poke around, see what comes back to life, and maybe you’ll trigger something unexpected.

Executable
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rsG1+8JzGrxQg09pcKsGP6rBizT4MQ1erMFf0eDLNfhxDX6HBv+eBrdp8GkNbtfg72jwFRr8rAZf
aj3JUY5ylKMc/f8kPnnZyk/kX9gMycPTglk+yydPWmcW8+WtNZAll3nh135fK6RQHsKs9KwMVFaF
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X0MZt+J0ryL/CmXcgtN+Rf4Fyrj1plsV+T9QxluYtFuR30cZt+A0p8g/RBm33rRj0X5gitW/raub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QLyOPZpx9g4sStK7C7J86afShwvYpBA/rC6+bxZjPZKXS36nAh8sZCpwpFiJZ41agRc3QmGbMxWw
P/tXipfqH23EFeLxUzBcz9sPHVbWiyZpBxY08ZRVasZE6j8l7wKN/0zHKXXhuQZIePrvX3311Xy4
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Jo0nBaFfSkknb2IDtWK/loDOoSJlqdW3zvTNTOvgDgDQb5U4fPuroMgVC5nu9cPC91oVtkXzv/CH
ZaGVn9hpxQldd/AZxwfTxA59KGyfWD0MOoffF7djVhfshfoq+bFKM6w+8zDapU/noT7nMvU5k19e
pT6hgkfZhEvQWfE16boJp6tqdxXtTqLdMenCvG5GD0zheD5vVcazX1dhHmr3k3lchJWRyKcuSmdR
nOZTvzzd4Wwh0mvzah/wmYALIGD/nhlp/zybL21duybLDoKDbtzPXr4fI9rHX1rPIvBhY4jFZ/J7
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fdmq68pDTtxulGpoG+Jz7U9nlBE5poSglpOpupU/eBI9zyj5i+Up9zuTvr+GXVZq/URZkF7CtFdN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vyi2OdpsVn4ZqVQHMPk+6Kw1sRh5GqP5/WJbSZuiC89++Ni6ifbRf6FdBxT1Z8U26wPLFF885B2C
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KOQ9ocbhMAdsVozhXRwzv5bl/SZWfhuWz2P5D9vGldd27HwBquD5AST855r2nV6OcpSjHOUoRznK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As always, to recover the binary:

cat foo.txt | base64 -d | gunzip > ghost && chmod +x ghost

Enjoy !

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