picoCTF 2022: binary-exploitation – basic-file-exploit

Ulli Weichert/ April 4, 2022/ IT-Security, Write-Ups/ 0Kommentare

basic-file-exploit Description The program provided allows you to write to a file and read what you wrote from it. Try playing around with it and see if you can break it! Connect to the program with netcat: $ nc saturn.picoctf.net 49698 The program’s source code with the flag redacted can be downloaded here. Solving Netcat into the service via given

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picoCTF 2022: Crypto – substitution challenges

Ulli Weichert/ April 4, 2022/ IT-Security, Write-Ups/ 0Kommentare

Substitution Challenges Because this challenges are all very similar, we will not describe them in own articles 🙂 . Solving Substitutions cypher replace the 26 letters of an alphabet with other letters (one letter matches only one other). If you can find out which letter was replaced with which letter, then you can crack this cypher relatively easily. The best

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picoCTF 2022: Crypto – Diffie Hellman

Ulli Weichert/ April 3, 2022/ IT-Security, Write-Ups/ 0Kommentare

diffie-hellman Description Alice and Bob wanted to exchange information secretly. The two of them agreed to use the Diffie-Hellman key exchange algorithm, using p = 13 and g = 5. They both chose numbers secretly where Alice chose 7 and Bob chose 3. Then, Alice sent Bob some encoded text (with both letters and digits) using the generated key as

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picoCTF 2022: Crypto – Morse Code

Ulli Weichert/ April 3, 2022/ IT-Security, Write-Ups/ 0Kommentare

morse-code Description Morse code is well known. Can you decrypt this? Download the file here. Wrap your answer with picoCTF{}, put underscores in place of pauses, and use all lowercase. Solving The soundfile is a morse code You could either translate it by your self with the morse alphabet or use this link Change all characters to lowercase and replace

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picoCTF 2022: Crypto – basic_mod2

Ulli Weichert/ April 2, 2022/ IT-Security, Write-Ups/ 0Kommentare

basic-mod2 Description A new modular challenge! Download the message here. Take each number mod 41 and find the modular inverse for the result. Then map to the following character set: 1-26 are the alphabet, 27-36 are the decimal digits, and 37 is an underscore. Wrap your decrypted message in the picoCTF flag format (i.e. picoCTF{decrypted_message}) Solving This challenge is similar

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picoCTF 2022: Crypto – basic_mod1

Ulli Weichert/ März 30, 2022/ IT-Security, Write-Ups/ 0Kommentare

basic-mod1 Description We found this weird message being passed around on the servers, we think we have a working decrpytion scheme. Download the message here. Take each number mod 37 and map it to the following character set: 0-25 is the alphabet (uppercase), 26-35 are the decimal digits, and 36 is an underscore. Wrap your decrypted message in the picoCTF

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