Big Zip writeup - Pico CTF ( General skills )

Solution -

Step 1: Download challenge files - First, download the big-zip-files.zip file provided by the challenge. Once downloaded, extract the contents: unzip big-zip-files.zip

After extraction, you’ll find an extensive hierarchy of directories and files. It would be impractical to open each file manually, so let’s move on to using command-line tools to automate the search process.

Step 2: Grepping the flag - Given that CTF flags typically follow a predictable pattern (e.g., picoCTF{}), we can use the grep command to search for files containing the flag.

Here’s the command I used:
grep -irl "picoctf*" ./

Explanation:
• grep is a command-line tool for searching text.
• -i makes the search case-insensitive.
• -r enables recursive searching through all directories and subdirectories.
• -l only prints the names of files that contain the matching pattern.

The output of this command provided the location of the file containing the flag.

Step 3 : Retrieve the Flag - Now that we know which file contains the flag, the next step is to open and read the file. Use the cat command to display its contents:cat ./big-zip-files/folder_pmbymkjcya/folder_cawigcwvgv/folder_ltdayfmktr/folder_fnpfclfyee/whzxrpivpqld.txt

Inside the file, you’ll find the hidden flag.