Flaw in Broadcom Wi-Fi Chipsets Illuminates Importance of Wireless Dependability and Business Continuity
A wireless vulnerability affecting Broadcom Wi-Fi chipsets represents a timely warning for organizations that need always-on wireless access and a prime example of how easy it is for one bad actor to upset the apple cart for every user connected to a n
StrongestLayer: Top ‘Trusted’ Platforms are Key Attack Surfaces
A wireless vulnerability affecting Broadcom Wi-Fi chipsets represents a timely warning for organizations that need always-on wireless access and a prime example of how easy it is for one bad actor to upset the apple cart for every user connected to a network. “The vulnerability can be exploited by sending a single frame over the air to the router within range, regardless of the configured network security level. The immediate effect is the loss of connection for all clients on the 5 GHz network, preventing reconnection until the router is manually restarted. This includes guest networks as well,” according to Black Duck researchers who discovered the vulnerability. “Ethernet connections and the 2.4 GHz network remain unaffected. After the restart, the attacker can immediately repeat the attack.” Black Duck’s CyRC team spotted the flaw during fuzz testing when they found Defensics anomaly test cases in which the network would stop working and require a manual reset of the router. If the vulnerability is exploited, attackers can make it so that an access point doesn’t respond to clients and can end client connections underway. The potential for widespread damage from exploitation of the vulnerability is even greater because of the popularity of Broadcom Wi-Fi chipsets. “Given the huge dependence on connectivity for personal devices and ever increasing numbers of IoT and smart devices, the impacts could be significant,” says James Maude, field CTO at BeyondTrust.The flaw also “has the potential to open the door to evil twin attacks where the real access point is knocked offline and a rogue one with the same name and password replaces it,” says Maude. “While the risks of network traffic interception have decreased thanks to the widespread adoption of HTTPS encryption, there is still the risk of captive portals,” he says. “When the user tries to restore their network connection, they are presented with a captive phishing portal requesting their personal or corporate credentials, leading to identity compromise.” Putting a more dangerous edge on the flaw is the fact that it doesn’t require authentication and encryption settings don’t thwart it. Noting that “implementation-level flaws in protocols, such as 802.11, are often more difficult to detect than cryptographic weaknesses” while “cryptographic weaknesses are easier to find because there are often only software dependencies,” Ben Ronallo, principal cybersecurity engineer at Black Duck, explains that “a researcher can build the code with breakpoints and watch the memory as the software executes.” But in that scenario, hardware dependencies are needed for testing. “The access point and a compatible antenna are required to perform this type of testing,” says Ronallo. “Further complicating things, the access point firmware is almost always closed source, which makes introspection much more difficult.” An attack from exploiting the flaw “is both easy to execute and highly disruptive, underscoring that even mature and widely deployed network technologies can still yield new and serious attack vectors,” says Saumitra Das, vice president of engineering at Qualys. “Because the attack can be launched by an unauthenticated client, encryption alone offers little protection.” And while this vulnerability initially “seems scary because it lets one unverified wireless frame keep disrupting a 5 GHz network until someone has to step in,” Randolph Barr, CISO at Cequence Security, says “the main risk isn’t simply the outage itself; it’s what long-term instability allows and how deeply it affects how the organization runs.” Past experience says “problems like this don’t usually stay limited to ‘IT issues,’” says Barr. “Most offices today use wireless connections more than traditional ones. Imagine being on a Zoom escalation call with a customer and the network goes down,” he says. “Even worse, imagine a board meeting where the CEO is discussing financial results, strategy, or an acquisition update, and the connection drops in the middle of the presentation.” That’s not just annoying, “it can hurt your credibility, slow down decision-making, and make consumers, partners, and executives lose trust in you,” says Barr. Fuzz testing has proven crucial in “validating protocol-stack implementations such as Wi-Fi,” over the years, uncovering “a wide range of vulnerabilities, including buffer overflows in drivers, denial-of-service conditions, remote code execution, and performance instability,” says Das. “Wi-Fi stacks are inherently complex, combining multiple state machines, cryptographic operations, and timing-dependent behaviors, which make them especially prone to subtle and dangerous implementation flaws.” Broadcom has issued a patch for the vulnerability, but that doesn’t mean protection will come quickly. “Remediation of vulnerabilities in hardware/firmware are always slower due to the downstream effects needing to be fully tested,” says Ronallo. That testing requires time from multiple, independent parties to ensure any changes don’t introduce additional bugs into their products.” While the industry says the deadline is 90 days, in reality, for hardware/firmware it’s closer to 180-plus days,” he explains. While the flaw is serious, Barr says it “doesn’t mean that someone can immediately take over the router or spy on it.” It does show, however, he says, “that the wireless control plane’s trust limits have broken down. This kind of issue is an area that many companies think is safe just because it is encrypted.” To counter these threats, security teams “must start with strong visibility into their environments through accurate asset inventory and continuous scanning, combined with the ability to tag assets by business criticality,” says Das. “It is not enough to know that access points are vulnerable; teams must understand where they are deployed and how much they matter to the business,” Das explains. “An access point supporting a small innovation lab carries very different risks than one embedded in a core manufacturing or logistics operation.” And Barr advises, “If you’re building networking in a hospital or your own home, segment your networks to prevent a direct path to your critical systems” and “audit for end of life/support systems (e.g., access points) and replace them when possible.” If the latter isn’t possible, “lock them down, have redundant logging in place, and monitor network edges with intrusion detection/prevention,” he says. And, of course, patch systems and consider setting up honeypots “to understand what attacks you could be facing.”
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