picoCTF2019 plumbing [General Skills]

picoCTF 2019 - Homepage

Sometimes you need to handle process data outside of a file. Can you find a way to keep the output from this program and search for the flag? Connect to 2019shell1.picoctf.com 21957.

Hints: Remember the flag format is picoCTF{XXXX} / What's a pipe? No not that kind of pipe... This kind

指定されたサーバに繋ぐと、大量のメッセージが表示される。

$ nc 2019shell1.picoctf.com 21957
This is defintely not a flag
I don't think this is a flag either
I don't think this is a flag either
This is defintely not a flag
I don't think this is a flag either
I don't think this is a flag either
Not a flag either
I don't think this is a flag either
I don't think this is a flag either
Not a flag either
I don't think this is a flag either
This is defintely not a flag
Not a flag either
This is defintely not a flag
I don't think this is a flag either
Not a flag either
Not a flag either
Not a flag either
Again, I really don't think this is a flag
Again, I really don't think this is a flag
Again, I really don't think this is a flag
Again, I really don't think this is a flag
Not a flag either
This is defintely not a flag
Not a flag either
I don't think this is a flag either
This is defintely not a flag
Not a flag either
Again, I really don't think this is a flag
Not a flag either
.......

この中からフラグを見つけ出すのは大変なので、パイプを使ってコマンドを連結して検索する。検索にはこの問題でも使用したgrepを使用する。

$ nc 2019shell1.picoctf.com 21957 | grep pico
picoCTF{digital_plumb3r_c1082838}

答え：picoCTF{digital_plumb3r_c1082838}

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