Introduction

Wireless networks are the backbone of modern connectivity, yet they remain vulnerable to a range of attacks due to the complexity and openness of the 802.11 protocol stack. Fuzzing automated testing with malformed or unexpected inputs has proven to be an effective method for uncovering these vulnerabilities. Penzzer, a comprehensive fuzzing tool, offers targeted modules for fuzzing management, control, and data frames, as well as the Simultaneous Authentication of Equals (SAE) exchange in WPA3 networks. Additionally, it includes a Denial-of-Service (DoS) attack module that leverages findings from the fuzzing process.

Unlike other tools such as OwFuzz, which require specialized hardware for operation, Penzzer works with common WiFi devices capable of packet injection. For instance, devices from Alfa Network are fully compatible, making Penzzer accessible to a broader range of security professionals and researchers.

Furthermore, Penzzer supports flexible deployment scenarios: it can operate as an Access Point (fuzzing WiFi clients) or as a Station (fuzzing WiFi servers), depending on the target of the fuzzing campaign.

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Understanding the 802.11 Frame Types

The IEEE 802.11 standard defines three primary types of frames, each serving distinct roles in wireless communication:

1. Management Frames: These frames establish and maintain connections between devices. They include beacons, probes, authentication, and association frames.
2. Control Frames: Used to facilitate the delivery of data frames, control frames manage access to the medium and include acknowledgments and request-to-send/clear-to-send (RTS/CTS) frames.
3. Data Frames: These carry the actual payload data between devices.

Each frame type has its own structure and significance, making them critical targets for fuzzing to identify potential vulnerabilities.

Penzzer tests various packet fields across these types, including Auth, Association, DeAssociation, DeAuth, EAP, Probe, Beacon, and Data, ensuring comprehensive coverage of the 802.11 protocol.

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Penzzer's Fuzzing Capabilities

Penzzer offers a suite of modules designed to fuzz different components of the 802.11 protocol:

1. Fuzzing Management Frames

Management frames are essential for network operation, and their manipulation can lead to significant disruptions. Penzzer allows fuzzing of these frames in two modes:

• Standard Mode: Frames are constructed with valid size values, adhering to the 802.11 standard. This ensures that frames are well-formed and less likely to be dropped by the target device.
• Random Mode: Size values are randomized, potentially creating malformed frames that can test the robustness of the target's frame parsing logic.

This module can be executed against any Access Point (AP), regardless of whether it supports WPA2 or WPA3.

2. Fuzzing Control Frames

Control frames manage the access to the wireless medium. Despite their simplicity, they are critical for network stability. Penzzer's control frame fuzzing module operates similarly to the management frame module, offering both standard and random modes.

3. Fuzzing Data Frames

Data frames carry the actual user data. Penzzer's data frame fuzzing module allows for the injection of malformed data frames to assess how devices handle unexpected payloads.

4. Fuzzing SAE Exchange

The Simultaneous Authentication of Equals (SAE) protocol is a key component of WPA3, providing a more secure authentication mechanism. Penzzer's SAE fuzzing module targets the SAE Commit and Confirm frames, which are crucial for establishing a secure connection.

This module offers two modes:

• Standard Mode: Uses specific, cherry-picked values for fuzzing, focusing on known edge cases.
• Extensive Mode: Performs exhaustive testing over the entire range of possible values, making it more time-consuming but thorough.

The module also includes a burst frame sending mode, which transmits multiple frames simultaneously to test the target's resilience under high-load conditions.

5. DoS Attack Module

Based on the data collected during the fuzzing process, Penzzer's DoS module can launch targeted attacks to exploit identified vulnerabilities. It offers two options:

1. Single Frame Replay: Replays individual frames that previously caused disruptions to confirm their impact.
2. Sequence Replay: Replays a sequence of frames leading up to a disruption, aiming to replicate complex attack scenarios.

This module is crucial for validating the real-world applicability of the fuzzing findings.

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Protocol Support

Penzzer supports fuzzing across multiple WiFi security protocols. Currently, it is capable of testing WEP, WPA, and WPA2 configurations. Support for WPA3 is under active development, with ongoing improvements to the SAE fuzzing module aimed at full compatibility.