Handshake Attacks
WiFi handshake attacks refer to a category of security exploits that target vulnerabilities in the process of establishing a secure connection (handshake) between a WiFi client device (such as a laptop or smartphone) and an access point (AP). The handshake process is a crucial step in WiFi Protected Access (WPA and WPA2) protocols for establishing encrypted communications between devices on a wireless network. Hereβs how WiFi handshake attacks work and their implications:
Overview of WiFi Handshake:
Purpose: The WiFi handshake process involves several key steps:
Association: The client sends a request to associate with an AP.
Authentication: The AP verifies the client's credentials.
Four-Way Handshake: Once authenticated, the client and AP perform a four-way handshake to negotiate encryption keys (Pairwise Transient Key, or PTK) used for securing subsequent data transmissions.
Security Goals: The handshake process aims to ensure:
Mutual authentication between client and AP.
Establishment of a shared encryption key (PTK) for secure data transmission using AES-CCMP (in WPA2) or TKIP (in WPA).
Types of WiFi Handshake Attacks:
Capture and Replay Attacks:
Description: An attacker captures the handshake packets exchanged during the initial association and authentication phases between the client and the AP.
Objective: The captured handshake can be replayed later to attempt offline brute-force attacks to recover the passphrase (Pre-Shared Key, or PSK) used for encrypting WiFi communications.
Brute-Force Attacks:
Description: Attackers use captured handshake packets to attempt to guess or crack the PSK through brute-force methods (trying multiple combinations of passwords).
Objective: Successful recovery of the PSK allows attackers to decrypt WiFi traffic, potentially gaining unauthorized access to the network.
Evil Twin Attacks:
Description: Attackers set up a rogue AP with the same SSID (network name) as a legitimate AP to trick clients into connecting to it.
Objective: By capturing handshake packets from clients connecting to the rogue AP, attackers can launch similar capture and replay or brute-force attacks to compromise client credentials or decrypt their traffic.
Deauthentication and Disassociation Attacks:
Description: Attackers send deauthentication or disassociation frames to force clients to disconnect from the legitimate AP and reconnect, triggering a new handshake process.
Objective: Capturing handshake packets during reconnection attempts allows attackers to exploit vulnerabilities in the handshake process or attempt to force the use of weaker encryption protocols (e.g., TKIP instead of AES-CCMP).
Mitigation Strategies:
To defend against WiFi handshake attacks, consider implementing these mitigation strategies:
Use Strong Passwords: Employ complex and unique PSKs to resist brute-force attacks.
Enable WPA3: Transition to the latest WiFi security protocol (WPA3) if supported, as it provides stronger protections against handshake attacks.
Network Monitoring: Continuously monitor WiFi networks for suspicious activity or unauthorized APs.
Firmware Updates: Keep APs and client devices updated with the latest firmware to patch known vulnerabilities.
Segmentation: Segment networks and apply access controls to limit the impact of compromised devices.
Intrusion Detection Systems (IDS): Deploy IDS to detect anomalies in WiFi traffic that could indicate handshake attacks.
By understanding and proactively addressing the vulnerabilities inherent in WiFi handshake protocols, organizations can better safeguard their wireless networks against exploitation and unauthorized access.
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