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Project Structure

project-directory/
├── generate_flag.py
├── image.py
├── fetch_flag.py
├── flag.txt
├── images/
├── temp_images/

Setup

1. Create Required Files and Directories

Run the following commands to set up the structure:

mkdir temp_images
touch flag.txt

2. Restrict Permissions

Ensure that flag.txt and the folders images/ and temp_images/ can only be accessed with sudo privileges:

sudo chown root:root flag.txt
sudo chmod 600 flag.txt

sudo chmod 700 images
sudo chmod 700 temp_images
sudo chown root:root images
sudo chown root:root temp_images

For Symbolic Link

ln -s [target_file] [link_name]

If you open file/folder direct without sudo access then:

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ cat flag.txt          
cat: flag.txt: Permission denied

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ cd temp-images 
cd: permission denied: temp-images

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ cd images      
cd: permission denied: images

Python Scripts

1. generate_flag.py

This script generates a flag, writes it to flag.txt, and removes the flag after sending it.

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ python3 generate_flag.py
Done.
Done.

flag.txt file:

┌──(root㉿kali)-[/home/V3c70r/Desktop]
└─# cat flag.txt
flag{6107274195}  

Symbolic link file also save the same flag that store in flag.txt

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ sudo cat symbolic_flag.txt                    
flag{6107274195}  

2. Image.py

This script handles moving an image from the images folder to the temp_images folder and deletes it after processing.

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ python3 image.py
Image added
Image added
Image added

temp-images folder:

┌──(root㉿kali)-[/home/naahl/Desktop/temp-images]
└─# ls
3.png

3. fetch_flag.py

• Option 1

┌──(V3c70r㉿kali)-[~/Desktop]
└─$ sudo python3 fetch_flag.py

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         ░ ░                                                 

Select an option:
1 - Kill the generate_flag.py process and fetch the flag
2 - Fetch the flag without killing the process
3 - Fetch Image from temp-images folder
4 - Exit
Enter your choice (1, 2, 3, or 4): 1

[+] Option 1 Selected: Killing the process...
[+] Searching for generate_flag.py process...
[+] Killing process with PID: 6453
[+] generate_flag.py process terminated successfully.
[+] Reading flag from flag.txt...
[+] Flag: flag{6107274195}

• Option 2

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      ░  ░ ░            ░          ░  ░ ░           ░ ░  ░   
         ░ ░                                                 

Select an option:
1 - Kill the generate_flag.py process and fetch the flag
2 - Fetch the flag without killing the process
3 - Fetch Image from temp-images folder
4 - Exit
Enter your choice (1, 2, 3, or 4): 2

[+] Option 2 Selected: Fetching the flag without killing the process...
[+] Reading flag from flag.txt...
[+] Flag: flag{6107274195}

• Option 3

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         ░ ░                                                 

Select an option:
1 - Kill the generate_flag.py process and fetch the flag
2 - Fetch the flag without killing the process
3 - Fetch Image from temp-images folder
4 - Exit
Enter your choice (1, 2, 3, or 4): 3

[+] Option 3 Selected: Fetching Image from temp-images...
[+] Checking temp-images folder for images...
[+] Image fetched: /home/naahl/Desktop/temp-images/3.png
[+] Image size: 6939636 bytes
[+] Image permissions: 744
[+] Image opened successfully.

The image saved in temp-image pops up on your screen like this:

• Option 4

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      ░  ░ ░            ░          ░  ░ ░           ░ ░  ░   
         ░ ░                                                 

Select an option:
1 - Kill the generate_flag.py process and fetch the flag
2 - Fetch the flag without killing the process
3 - Fetch Image from temp-images folder
4 - Exit
Enter your choice (1, 2, 3, or 4): 4

[+] Exiting. Goodbye!

Usage

• Run the scripts with to ensure proper access to restricted files and folders.
• Start the fetch_flag.py script to interact with the system.

python3 fetch_flag.py

• Follow the menu to fetch flags or images.

Notes

• Ensure you have the necessary permissions to run these scripts.
• Use this system responsibly and in compliance with your organization's security policies.