Insecure encryption algorithm - AES

Need

Implementation of secure encryption algorithms

Context

Usage of TypeScript for type-checking and compiling JavaScript code
Usage of Express for building web applications and APIs
Usage of crypto for cryptographic operations and secure data handling

Description

Non compliant code

import express from 'express';
import crypto from 'crypto';

const app = express();

app.get('/encrypt', (req, res) => {
  const plaintext = 'Sensitive information';
  const key = 'insecurekey';

  const cipher = crypto.createCipher('aes-128-ecb', key);
  let encrypted = cipher.update(plaintext, 'utf8', 'hex');
  encrypted += cipher.final('hex');

  res.send(encrypted);
});

app.get('/decrypt', (req, res) => {
  const encrypted = req.query.encrypted as string;
  const key = 'insecurekey';

  const decipher = crypto.createDecipher('aes-128-ecb', key);
  let decrypted = decipher.update(encrypted, 'hex', 'utf8');
  decrypted += decipher.final('utf8');

  res.send(decrypted);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The vulnerability in this code lies in the insecure encryption algorithm being used, specifically the AES encryption with ECB mode and PKCS1Padding. ECB mode is considered insecure because it does not provide proper randomization of the plaintext blocks, which can lead to patterns in the encrypted data. PKCS1Padding is also vulnerable to certain attacks.

In the /encrypt route, the code creates an AES cipher using the crypto.createCipher method with the 'aes-128-ecb' algorithm and an insecure key. It then encrypts the plaintext using this cipher and sends the encrypted data as the response.

In the /decrypt route, the code retrieves the encrypted data from the query parameter and attempts to decrypt it using an AES decipher created with the same insecure key and 'aes-128-ecb' algorithm. The decrypted data is then sent as the response.

This vulnerable code allows an attacker to easily decrypt the information encrypted with this algorithm. The lack of proper randomization and the use of an insecure key make it susceptible to attacks such as known-plaintext attacks and brute-force attacks.

To mitigate this vulnerability, it is recommended to use secure encryption algorithms such as RSA/NONE/OAEPwithSHA-256andMGF1Padding or use implementations with the GCM mode encryption algorithm. Additionally, using a strong and secure key is crucial for ensuring the confidentiality of the encrypted data.

Steps

Replace the insecure encryption algorithm AES/ECB/PKCS5PADDING with a secure algorithm such as AES/GCM/NoPadding.
Generate a secure and random encryption key.
Update the code to use the new encryption algorithm and key.
Ensure that the encryption key is securely stored and not hardcoded in the code.
Update the decryption logic to use the new encryption algorithm and key.
Test the updated code to ensure it functions correctly and securely.

Compliant code

import express from 'express';
import crypto from 'crypto';

const app = express();

app.get('/encrypt', (req, res) => {
  const plaintext = 'Sensitive information';
  const key = crypto.randomBytes(32); // Generate a secure and random encryption key

  const cipher = crypto.createCipheriv('aes-256-gcm', key, null);
  const encrypted = Buffer.concat([cipher.update(plaintext, 'utf8'), cipher.final()]);

  res.send({
    encrypted: encrypted.toString('hex'),
    iv: cipher.getIV().toString('hex'),
    authTag: cipher.getAuthTag().toString('hex')
  });
});

app.get('/decrypt', (req, res) => {
  const encrypted = Buffer.from(req.query.encrypted as string, 'hex');
  const iv = Buffer.from(req.query.iv as string, 'hex');
  const authTag = Buffer.from(req.query.authTag as string, 'hex');
  const key = req.query.key as string; // Retrieve the encryption key from a secure storage

  const decipher = crypto.createDecipheriv('aes-256-gcm', key, iv);
  decipher.setAuthTag(authTag);

  let decrypted = decipher.update(encrypted);
  decrypted = Buffer.concat([decrypted, decipher.final()]);

  res.send(decrypted.toString('utf8'));
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

The fixed code addresses the vulnerability by using a secure encryption algorithm, specifically AES-256-GCM. Here is an explanation of the changes made:

The code imports the necessary modules, including the 'express' module for creating the server and the 'crypto' module for cryptographic operations.
The code creates an instance of the express application.
The '/encrypt' route is defined to handle encryption requests. Inside the route handler, a plaintext message is defined and a secure and random encryption key is generated using the 'crypto.randomBytes' function.
The 'crypto.createCipheriv' function is used to create a cipher object with the AES-256-GCM algorithm, the generated key, and a null initialization vector (IV). The 'cipher.update' and 'cipher.final' functions are then used to encrypt the plaintext message.
The encrypted message, IV, and authentication tag are sent as a response in the form of a JSON object.
The '/decrypt' route is defined to handle decryption requests. The encrypted message, IV, and authentication tag are extracted from the request query parameters.
The encryption key is retrieved from a secure storage (not shown in the code) and used to create a decipher object with the 'crypto.createDecipheriv' function, specifying the AES-256-GCM algorithm, the key, and the IV.
The authentication tag is set on the decipher object using the 'decipher.setAuthTag' function.
The 'decipher.update' and 'decipher.final' functions are used to decrypt the encrypted message.
The decrypted message is sent as a response.
The server is started and listens on port 3000.

By using the AES-256-GCM algorithm and properly handling the encryption and decryption process, the code ensures the security of the encrypted data and mitigates the vulnerability associated with insecure encryption algorithms.

References

265.Insecure encryption algorithm - AES

Need​

Context​

Description​

Non compliant code​

Steps​

Compliant code​

References​