Replay Attacks - CompTIA Security+ SY0-701- 2.4

Understanding Replay Attacks and Session Hijacking

Overview of Network Traffic

• Network traffic typically flows from a client to a server, with potential sensitive information being exchanged that attackers may seek to intercept.

• Attackers can perform replay attacks if they obtain the necessary information, which can be challenging. Techniques include using physical network taps or malware.

Mechanics of Replay Attacks

• A replay attack allows an attacker to impersonate a victim by resending captured data, often requiring prior on-path attacks for data collection.

• One specific type of replay attack is "pass the hash," where an attacker captures username and hashed password during authentication.

Preventing Replay Attacks

• To mitigate replay attacks, encryption should be employed to obscure traffic and prevent unauthorized access to sensitive information.

• Implementing salting techniques for passwords ensures unique hashes are generated each time, making it difficult for attackers to reuse captured hashes.

Risks Associated with Browser Cookies

• Attackers target browser cookies as they store valuable session management information but do not contain executable code.

• Cookies can reveal usernames and other details that could compromise user privacy and security.

Session Hijacking Explained

• An attacker can exploit session IDs obtained from cookies to gain unauthorized access without needing login credentials.

• Once in possession of a session ID, attackers can interact with web servers as if they were the legitimate user.

Tools and Techniques for Exploitation

• Packet capture tools like Wireshark or Kismet allow attackers to gather headers containing sensitive information such as session IDs.

• Cross-site scripting (XSS) exploits can also facilitate the extraction of sensitive data from client machines.

Mitigation Strategies Against Session Hijacking

• Encrypting all communications between devices prevents interception of session IDs and personal data during transmission.