Collaborative Development - PicoCTF Write-Up
A write-up on the challenge Collaborative Development.
Introduction
Today we’re going to take a look at the challenge Collaborative Development on PicoCTF by Jeffery John. The difficulty is easy.
Challenge Description
My team has been working very hard on new features for our flag printing program! I wonder how they’ll work together? You can download the challenge files here:
Solution
Let’s begin by extracting the contents of the downloaded .zip file and then navigate to the unzipped directory:
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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.
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┌──(printn㉿kali)-[~/drop-in]
└─$ ls -la
total 16
drwxr-xr-x 3 printn printn 4096 Mar 11 2024 .
drwx------ 14 printn printn 4096 Nov 7 11:40 ..
drwxr-xr-x 8 printn printn 4096 Mar 11 2024 .git
-rw-r--r-- 1 printn printn 30 Mar 11 2024 flag.py
Let’s try running the flag.py and see what we get.
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┌──(printn㉿kali)-[~/drop-in]
└─$ python3 flag.py
Printing the flag...
Hmmm, seems like something may be hidden or unfinished. We can try checking if there are other branches with different code.
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┌──(printn㉿kali)-[~/drop-in]
└─$ git branch -a
feature/part-1
feature/part-2
feature/part-3
* main
Let’s switch to the feature/part-1 branch.
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┌──(printn㉿kali)-[~/drop-in]
└─$ git checkout feature/part-1
Switched to branch 'feature/part-1'
┌──(printn㉿kali)-[~/drop-in]
└─$ ls -la
total 16
drwxr-xr-x 3 printn printn 4096 Nov 7 11:46 .
drwx------ 14 printn printn 4096 Nov 7 11:40 ..
drwxr-xr-x 8 printn printn 4096 Nov 7 11:46 .git
-rw-rw-r-- 1 printn printn 64 Nov 7 11:46 flag.py
┌──(printn㉿kali)-[~/drop-in]
└─$ python3 flag.py
Printing the flag...
picoCTF{t3@mw0rk_
Great! Now we have the first part of the flag. Instead of manually checking out each branch and assembling the flag, we can use the following command:
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┌──(printn㉿kali)-[~/drop-in]
└─$ git checkout feature/part-1 && cat flag.py && git checkout feature/part-2 && cat flag.py && git checkout feature/part-3&& cat flag.py
Switched to branch 'feature/part-1'
print("Printing the flag...")
print("picoCTF{t3@mw0rk_", end='')Switched to branch 'feature/part-2'
print("Printing the flag...")
print("m@k3s_th3_dr3@m_", end='')Switched to branch 'feature/part-3'
print("Printing the flag...")
print("w0rk_6c06cec1}")
Flag: picoCTF{t3@mw0rk_m@k3s_th3_dr3@m_w0rk_6c06cec1}