In 2019, cybersecurity researchers Mathy Vanhoef and Eyal Ronen disclosed a series of vulnerabilities called Dragonblood Vulnerabilities. This suite of exploits targeted the next-generation Wi-Fi security protocol, WPA3, introduced to address the well-documented weaknesses of its predecessor, WPA2. Despite its promise of enhanced security, WPA3 was susceptible to sophisticated attacks that exposed flaws in its Simultaneous Authentication of Equals (SAE) handshake- a key exchange mechanism designed to offer forward secrecy and resistance to offline dictionary attacks. This SAE handshake is also known as the DrangonFly handshake.
To improve security and reduce the risk of brute force attacks while enabling robust encryption, SAE replaced the Pre-Shared Key (PSK) method used in WPA2. However, the Dragonblood vulnerabilities demonstrated that WPA3-SAE was not impervious. The key exchange process, intended to strengthen Wi-Fi security, became the focal point of side-channel exploits.
The Primary vulnerability exploited by this attack lies in the timing side-channel leaks during the SAE handshake process. These leaks occur due to the way the protocol processes the passwords. An attacker can gain partial insights into the password or cryptographic key being used by analyzing the timing of cryptographic operations or observing cache access patterns. Later, this information can be used to compromise the network’s security.
The Dragonblood vulnerabilities affect wireless networks by targeting the WPA3-SAE handshake, leading to following primary issues:
- Timing-Based Side-Channel Attacks: These attacks exploit discrepancies in the execution time of cryptographic operations within WPA3-SAE. The differences in processing time for varying passwords or keys inadvertently leak partial information about the credentials. Attackers can use this information to refine guesses, making brute-force attacks significantly more efficient iteratively.
- Cache-based Side-Channel Attacks: The attackers observe memory access patterns on the victim’s device during the handshake process. These patterns can leak information about the password being used. This can be achieved by analyzing network traffic or controlling applications on the victim’s device.
- Downgrade Attacks: Another critical vector exploited by Dragonblood is the forced downgrade of WPA3 connections to WPA2. Many devices maintain backward compatibility for legacy support. Attackers can exploit this by triggering a fallback to WPA2, susceptible to well-documented vulnerabilities such as the KRACK exploit. This effectively bypasses the security enhancements introduced in WPA3.
- DoS Attacks: The SAE handshake’s computational demands can be exploited by sending forged commit frames to overload the access point, causing high CPU usage and denial of service.
EAP-PWD, which also uses Dragonfly or SAE handshake, is also vulnerable to similar attacks, including invalid curve and reflection attacks that allow bypassing authentication or impersonating the server.
The Dragonblood attack underlines several lessons for the community:
- Security is a Continuous Process: No protocol or system is impervious to vulnerabilities. Modern, well-designed technologies like WPA3 require ongoing evaluation, rigorous testing, and iterative updates to address newly discovered threats.
- Mitigating Side-Channel Attacks: Side-channel attacks are frequently overlooked while designing the protocol. Therefore, Developers must address these potential weaknesses by implementing constant-time cryptographic operations and securing memory access patterns to prevent inadvertent data leakage.
- Risks of Backward Compatibility: While maintaining backward compatibility is necessary for legacy device support, it can introduce significant security risks. As seen with Dragonblood attacks, these trade-offs must be carefully managed to avoid undermining the security of modern systems.
Significant efforts have been made to fortify WPA3 against such attacks. The Wi-Fi Alliance and other stakeholders have implemented updates to mitigate the timing leaks and harden the SAE handshake process. These mitigations aim to close the gaps that Dragonblood exposed to ensure WPA3 evolved into a more resilient standard than it is now.
Adopting the best practices in wireless security remains essential for organizations and individuals. Some actionable steps include:
- Regular Firmware Updates
- Strong Password Management
- Disable Legacy Compatibility
- Comprehensive Security Audits
The Dragonblood attack was a reminder of the complexities of securing wireless communication. Even though the Dragonblood attack revealed weaknesses in WPA3, it also provided an opportunity to strengthen the protocol and reinforce the foundational principles of wireless security.
