Quartet Writeup

Solve by thewhiteh4t

Four files are given with .z01 extension, running file command on them shows the following output :

quartet.z01:  Zip multi-volume archive data, at least PKZIP v2.50 to extract
quartet.z02:  data
quartet.z03:  data
quartet.z04:  Zip archive data, made by v3.0 UNIX, extract using at least v2.0, last modified, last modified Sun, May 10 2025 04:28:04, uncompressed size 2035495, method=deflate

Unzipping them leads to another file named quartet.jpeg. By running strings command on the image and grepping for flag string we can get the flag :

strings quartet.jpeg | grep flag
flag{8f667b09d0e821f4e14d59a8037eb376}

Key Learning & Takeaways

• Run strings : You’d be surprised how often a flag or a crucial hint is just sitting there in plain text.
• Check the file type with file : A simple file command can tell you a lot about what you’re dealing with. Knowing this helps you pick the right tools for the job.
• Keep an eye out for flag formats : Most CTFs use a consistent flag format (like flag{...}).