- Broadcom fixed a high severity DoS flaw in the chipset software
- ASUS RT-BE86U confirmed vulnerable; other models may be affected
- Attack crashes 5G Wi-Fi and requires manual restart of router
Broadcom has fixed a bug in its chipset software that allowed malicious actors to trigger denial of service (DoS) attacks on specific routers.
The vulnerability, which has not yet been assigned a CVE, was assigned a severity score of 8.4/10 (High), and customers are encouraged to contact Broadcom for more details on the affected products, versions, and fixes.
Recently, security researchers from the Black Duck Cybersecurity Research Center (CyRC) were testing the interoperability of Defensics® Fuzzing with 802.11 protocol test suites against ASUS routers.
Denial of service on the router
Defensics Fuzzing is an automated software security testing method that sends large volumes of random, malformed input to a system to see how it behaves. CyRC generated malformed 802.11 (Wi-Fi) protocol traffic and sent it to the Asus routers to see what would happen, and the router failed.
“During testing, the CyRC team found test cases of Defensics anomalies that caused the network to stop working until the router was manually rebooted,” the researchers said in a security advisory.
“This vulnerability allows an attacker to cause the access point to become unresponsive to all clients and terminate any client connections in progress. If data transmission to downstream systems is in progress, the data may become corrupted or, at a minimum, the transmission will be interrupted.”
In theory, a threat actor could send a single frame over the air to the router, regardless of the configured network security level. Almost instantly, all 5G network clients will lose their signal and will not be able to reconnect until the router is manually reset. It was said that Ethernet connections and the 2.4 GHz network are not affected by this bug.
Further investigation determined that the problem was in the Broadcom chipset software, and after contacting the manufacturer, the company came back with a patch.
So far, at least one model has been found vulnerable: the Asus RT-BE86U. However, CyRC said other devices using the same wireless chipset and/or associated software “could be similarly affected.” However, users are certainly advised to contact Broadcom, as a complete list of affected products is not publicly available.
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