Blame Game - PicoCTF Write-Up

Introduction

Hello👋 Today we’re going to take a look at the challenge Blame Game on PicoCTF by Jeffery John. The difficulty is easy.

Challenge Description

Someone’s commits seems to be preventing the program from working. Who is it?

You can download the challenge files here:

• challenge.zip

Solution

Let’s begin by extracting the contents of the downloaded .zip file and then navigate to the unzipped directory:

unzip challenge.zip
cd drop-in/

Inside this folder, we notice the presence of a .git directory, which indicates that Git version control has been initialized.

┌──(printn㉿printn)-[~/Downloads/drop-in]
└─$ ls -la
total 16
drwxr-xr-x 3 printn printn 4096 Mar 11  2024 .
drwxr-xr-x 3 printn printn 4096 Oct  6 07:24 ..
drwxr-xr-x 8 printn printn 4096 Mar 11  2024 .git
-rw-r--r-- 1 printn printn   22 Mar 11  2024 message.py

The challenge description says that someone made a mistake in the code and we must find out who did it. To check all the changes made to the message.py file in every commit, we can use this command:

git log -p message.py  

This command provides the commit history along with patches, showing the modifications made to the specified file.

┌──(printn㉿printn)-[~/Downloads/drop-in]
└─$ git log -p message.py  
commit 8c83358c32daee3f8b597d2b853c1d1966b23f0a
Author: picoCTF{@sk_th3_1nt3rn_2c6bf174} <ops@picoctf.com>
Date:   Tue Mar 12 00:07:11 2024 +0000

    optimize file size of prod code

diff --git a/message.py b/message.py
index 7df869a..326544a 100644
--- a/message.py
+++ b/message.py
@@ -1 +1 @@
-print("Hello, World!")
+print("Hello, World!"

commit caa945839a2fc0fb52584b559b4e89ac7c46bf54
Author: picoCTF <ops@picoctf.com>
Date:   Tue Mar 12 00:07:11 2024 +0000

    create top secret project

diff --git a/message.py b/message.py
new file mode 100644
index 0000000..7df869a
--- /dev/null
+++ b/message.py
@@ -0,0 +1 @@
+print("Hello, World!")

Flag: picoCTF{@sk_th3_1nt3rn_2c6bf174}