Authentication / Key Exchange without Entity Authentication

Description

Key Exchange without Entity Authentication is a type of authentication vulnerability (CWE-287) that occurs when an application does not authenticate the entities involved in a key exchange. This can allow an attacker to impersonate the legitimate entity, gain access to the system, and manipulate the key exchange. This vulnerability is commonly seen in web and API applications (OWASP Testing Guide).

Risk

This vulnerability can cause a major security breach in the system, as the attacker can gain access to the system and manipulate the key exchange. This can lead to unauthorized access to sensitive data and damage to the system as a whole.

Solution

The best solution to this vulnerability is to implement an authentication protocol that checks the identity of both entities involved in the key exchange. This can be accomplished by using Transport Layer Security (TLS) or Public Key Infrastructure (PKI).

Example

The following example code shows how an attacker can exploit the vulnerability of key exchange without entity authentication:

// attacker code
PublicKey attackerPublicKey = new PublicKey();

// legitimate code
PublicKey legitimatePublicKey = new PublicKey();

// malicious code
byte[] keyBytes = new byte[32];
SecureRandom.nextBytes(keyBytes);
SecretKey secret = new SecretKeySpec(keyBytes, "AES");

// attacker code
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, legitimatePublicKey);
byte[] encryptedSecret = cipher.doFinal(secret.getEncoded());

// legitimate code
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, attackerPublicKey);
byte[] decryptedSecret = cipher.doFinal(encryptedSecret);

// attacker code
SecretKey secret = new SecretKeySpec(decryptedSecret, "AES");
// attacker can use the secret key to gain access to the system