WPA3-Personal introduced the stateful Simultane-ous Authentication of Equals (SAE) handshake protocol to achieve forward secrecy and resistance to passphrase guessing attacks during Wi-Fi connection bootstrapping, guarantees that are lacking in WPA2-Personal. However, the initial design of WPA3-Personal with SAE was susceptible to connection downgrade and denial-of-service (DoS) attacks. The current, enhanced version introduces mechanisms to mitigate these vulnerabilities. Enabling these security-enhancing mechanisms, however, results in a variable-structured, context-sensitive packet format that can be challenging to parse and interpret correctly. Misparsing SAE handshake packets can negatively impact Wi-Fi protocol security. To uncover SAE handshake packet misparsing in commercial-off-the-shelf (COTS) Wi-Fi access points (APs), we present Saecred,a packet-structure-guided, SAE-state-aware black-box fuzzer. Saecredreduces the underlying problem of misparsing discovery to a two-dimensional search problem, where the dimensions are the packet structure and the underlying SAE protocol state. It solves this search problem by combining Iterative Deepening Search (IDS) with a context-sensitive grammar-based fuzzing approach, where the latter relies on a Syntax-Guided Synthesis (SyGuS) solver. Saecred'seffectiveness is demonstrated by evaluating it on 6 COTS APs and the widely used open-source hostapd. Our evaluation discovered several instances of 4 classes of bugs. Bugs in two of these classes violate the two fundamental guarantees SAE expects to achieve (i.e., resistance to downgrade and DoS attacks). We reported our findings to the relevant stakeholders, which resulted in patches and security advisories.

We present our experience of formally verifying the desired security properties of the Uptane over-the-air (OTA) software update framework against a set of applicable threat models. Uptane is gaining traction in the automobile industry and is widely considered the next de-facto standard for OTA automobile software updates. The security of Uptane is of utmost importance because modern automobiles rely on software for their safety-critical functionalities and, especially, require OTA software updates to add new safety features or patch bugs in existing ones. Design flaws in Uptane can either violate the integrity of the updates to be installed or prevent vehicles from installing new updates, both of which can cause severe safety issues. Previous approaches to protocol verification either fail to capture the necessary features of Uptane or suffer from termination issues due to Uptane’s complexity. A key component of our approach lies in the eager combination of an infinite-state model checker and a cryptographic protocol verifier, where (in contrast to prior lazy approaches) we are able to eliminate a key manual step in the workflow while enabling reasoning over more fine-grained message structures. In addition, our approach utilizes two proven soundness- and completeness-preserving state-space-reduction optimizations for computational tractability, as well as a meta-level analysis technique that makes it feasible to reason over Uptane’s set of optional protocol features. Our approach is able to discover six new vulnerabilities while rediscovering all five known ones. While there have been previous analyses of Uptane’s security properties, they either missed design flaws identified by our approach or suffered from coverage and termination issues. The Uptane standards body has positively acknowledged our findings and has suggested updates to the protocol specification documents to address them.