The Lucky Thirteen vulnerability is a type of attack that exploits a timing vulnerability in the implementation of the TLS (Transport Layer Security) protocol, particularly in its handling of certain cipher modes. Specifically, it targets the way certain block ciphers handle padding in the encryption process, allowing an attacker to gain insights into encrypted messages through timing measurements.

Key security impacts of the Lucky Thirteen attack include:

- **Timing Attack**: Attackers can exploit timing discrepancies in how the server processes encrypted messages, revealing information about the plaintext.
- **Message Recovery**: Through repeated observations of timing differences, attackers can recover portions of the encrypted message, potentially leading to full plaintext recovery.
- **Confidentiality Compromise**: Successful execution of the attack can result in exposure of sensitive information, undermining the confidentiality guarantees of SSL/TLS.

Example of a scenario:

- An attacker monitors the time it takes for a server to respond to encrypted messages, making small modifications to the ciphertext to deduce information about the original plaintext based on response times.

This attack primarily affects implementations of TLS that do not properly handle padding and timing checks during decryption.