# easycrack

<div align="left"><figure><img src="/files/n0k56Ui7rmWyHeReQgyO" alt=""><figcaption></figcaption></figure></div>

{% file src="/files/VzdBIEfuVPhE7BFBUcRG" %}

first let's run the binary

<div align="left"><figure><img src="/files/FoYBhx92arAQmojVuZZM" alt=""><figcaption></figcaption></figure></div>

so we can see that this binary asking for which is the flag let's open the file using ghidra

we have one function called main

<div align="left"><figure><img src="/files/Hze3mi6VqPzg1kskXCuT" alt=""><figcaption></figcaption></figure></div>

1. first thing a user is prompted to enter a key&#x20;
2. The program calculates the sum of ASCII values of characters in the entered key
3. It checks if the sum is equal to `0x539` <mark style="color:green;">(1337)</mark> and if the length of the key is `0xc` <mark style="color:green;">(12)</mark>.
4. If the conditions are met, it prints "Nice key :)" along with the entered key; otherwise, it prints "Bad Key :(" with the entered key.

so we know that the flag starts with `flag{` and ends with `}` so we know 6 characters from the key we need to find the other 6 characters by bruteforcing them and checking if the sum is equal to 1337&#x20;

we know from the previous found flags the flag is always constructed using lowercase characters and numbers and \_

### Exploit :&#x20;

```python
def generate_key():
    # Known prefix and suffix
    prefix = "flag{"
    suffix = "}"

    # Iterate through all ASCII characters for the middle part
    for char1 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
        for char2 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
            for char3 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
                for char4 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
                    for char5 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
                        for char6 in 'abcdefghijklmnopqrstuvwxyz_0123456789':
                            middle_part = f"{char1}{char2}{char3}{char4}{char5}{char6}"

                            # Concatenate the parts to form the complete key
                            generated_key = f"{prefix}{middle_part}{suffix}"

                            # Calculate the sum of ASCII values of characters
                            key_sum = sum(ord(char) for char in generated_key)
                            
                            # Check conditions
                            if key_sum == 0x539 and len(generated_key) == 0xc:
                                return generated_key

# Generate a key and print it
generated_key = generate_key()
print(f"Generated key: {generated_key}")

```

executing the script and waiting for a couple of minutes we get the correct key

<div align="left"><figure><img src="/files/0pjVxwVWwCHjNEGpTFc1" alt=""><figcaption></figcaption></figure></div>

### Flag :&#x20;

```
flag{aawzzz}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://sayonara.gitbook.io/writeups/ctf/the-cyber-cooperative-ctf-2023/rev/easycrack.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.