Ben Seri and Gregory Vishnepolsky from the society armis recently disclosed eight vulnerabilities present in various BlueTooth stacks. Their paper “The dangers of Bluetooth implementations: Unveiling zero day vulnerabilities and security flaws in modern Bluetooth stacks” thoroughly describes these vulnerabilities and derives some interesting lessons.

Some vulnerabilities may allow taking control of the Bluetooth device. These exploits do not need the target to be in discoverable mode. They just need to know the Bluetooth MAC address (BDADDR). Contrary to common belief, it is guessable even for non-discoverable devices. If the target generates Bluetooth traffic, then it BDAADR is visible in the access code. If it is not generating traffic, the widely accepted convention to use the same MAC address for Wifi than for Bluetooth may reveal it.

Once the attacker knows the BDADDR, he can use the exploits. One powerful vulnerability is due to some lack of implementation guidelines in the specifications for the “Just Works” authentication. For Android and Windows, if the attacker claims to be “No Input No output, No Man in the middle protection required and no bonding,” the target stealthily accepts the connection with limited security capabilities for a short period of time (due to the no bonding). Of course, any service that would require MiTM protection or bonding, and verifies the requirement, will refuse to operate over such connection. For Apple, the connection requests a validation by the user.

Once the attacker is linked to the unknowing target, it can try many attacks. My preferred ones are CVE-2017-0783 and CVE-2017-8628. They use a flaw in the specification of the Personal Area Network (PAN). This service has a low-level security requirement. This means that the previous attack grants access to the PAN without any authorization! The attacker can mount a pineapple attack over Bluetooth without the target being aware. In a Wifi Pineapple, the attacker impersonates an already known WIFI public network and can act as a man in the middle. In this case, the pineapple does not need to be a known network. Redoutable.

The PAN specification dated from 2003 and was never since revised. “Just works” and the newer authentication protocols were specified more recently. They changed the trust model and trust context. The older specifications were not analyzed to identify potential impacts.

The other vulnerabilities allow either buffer overflows or data leakage by exploring more than the attributed spaces.

The disclosure was part of a coordinated disclosure with Google, Microsoft, and Linux kernel team.

Conclusion: Verify that you installed the August and September security patches for your devices. They contain patches to these vulnerabilities.


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