picoCTF 2025: hashcrack

Problem

Solution

Upon connecting to this endpoint, we’re given a series of hashes which we must identify and crack. I like cats so Hashcat is my top choice :)

Hash 1

482c811da5d5b4bc6d497ffa98491e38

This first hash is 32 hexadecimal characters, which is 128 bits. The most popular 128-bit hash is MD5 (mode 0 in Hashcat), so let’s run it with the RockYou dataset:

hashcat -m 0 -a 0 ciphertext1 /usr/share/wordlists/rockyou.txt

Within moments, we find 482c811da5d5b4bc6d497ffa98491e38:password123. Entering password123 into the oracle takes us to the next hash.

Hash 2

b7a875fc1ea228b9061041b7cec4bd3c52ab3ce3

This next hash is 40 hexadecimal characters, or 192 bits. Very few hashes are of this length, SHA-1 (mode 100) being one of the most popular, so let’s try that:

hashcat -m 100 -a 0 ciphertext2 /usr/share/wordlists/rockyou.txt

Once again, the hash is cracked in moments: b7a875fc1ea228b9061041b7cec4bd3c52ab3ce3:letmein. Inputting letmein leads us to the final hash.

Hash 3

916e8c4f79b25028c9e467f1eb8eee6d6bbdff965f9928310ad30a8d88697745

The final hash is 64 characters, or 256 bits. SHA-256 (mode 1400) is the most common. Once again:

hashcat -m 1400 -a 0 ciphertext3 /usr/share/wordlists/rockyou.txt

And similarly, we find 916e8c4f79b25028c9e467f1eb8eee6d6bbdff965f9928310ad30a8d88697745:qwerty098. After submitting qwerty098, we are given the flag.