What techniques are there for preventing radio-signal replay attacks

Question

Replay attacks capture and retransmit wireless signals to bypass authentication. What security measures can be used to prevent replay attacks in wireless communication?

Answer 1

​Replay attacks in wireless communications occur when an attacker intercepts and retransmits valid data transmissions to gain unauthorized access or disrupt network operations. Implementing robust security measures is essential to prevent such attacks. Key techniques include:​

1. Nonces (Numbers Used Once): Incorporate unique, random values in each communication session to ensure that captured data cannot be reused. Nonces are effective in challenge-response authentication protocols, where the server issues a nonce, and the client responds with a value derived from it, verifying authenticity.

2. Timestamps: Attach timestamps to transmitted messages to verify their freshness. The receiver checks that the timestamp falls within an acceptable time window, rejecting messages outside this range to thwart replay attempts. ​

3. Message Authentication Codes (MACs): Utilize MACs to ensure data integrity and authenticity. By including a MAC in each message, any alteration or unauthorized retransmission can be detected, as the MAC will no longer be valid.

4. Challenge-Response Protocols: Implement protocols where the server sends a challenge (e.g., a random number) to the client, which must respond with the correct answer. This method verifies that the client is legitimate and prevents replay attacks, as the challenge is different for each session.

5. Secure Communication Protocols: Adopt protocols like SSL/TLS and IPsec that incorporate mechanisms to prevent replay attacks. These protocols use sequence numbers and other techniques to ensure the authenticity and integrity of transmitted data.

6. One-Time Passwords (OTPs): Employ OTPs that are valid for a single session or transaction. Even if an attacker captures the OTP, it cannot be reused, effectively mitigating replay attacks. ​

7. Protected Management Frames (IEEE 802.11w): Implement the IEEE 802.11w standard to protect management frames in Wi-Fi networks. This standard enhances security by providing data confidentiality, integrity, and replay protection for management frames, preventing attackers from exploiting unprotected frames.

Combining these techniques can significantly enhance the security of wireless communications, effectively mitigating the risk of replay attacks.