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BLUFFS Bluetooth Attack: Guard Up! 🚨📲

: bluffs bluetooth attack: guard up! 🚨📲

New Bluffs Bluetooth Attack Exposes Devices to Adversary-in-the-Middle Attacks

Bluetooth Classic's forward secrecy and future secrecy guarantees have been broken by a series of novel attacks named BLUFFS. These attacks enable adversary-in-the-middle scenarios between two already connected peers, allowing device impersonation and machine-in-the-middle across sessions by only compromising one session key. The issues impact Bluetooth Core Specification 4.2 through 5.4 and are tracked under the identifier CVE-2023-24023.

The attacks leverage two new flaws in the Bluetooth standard's session key derivation mechanism that allow the derivation of the same key across sessions. This is made possible by weaponizing four architectural vulnerabilities in the specification of the Bluetooth session establishment process to derive a weak session key, and subsequently brute-force it to spoof arbitrary victims.

The attack works by allowing an AitM attacker impersonating the paired device to negotiate a connection with the other end to establish a subsequent encryption procedure using legacy encryption. In doing so, an attacker in proximity may ensure that the same encryption key is used for every session while in proximity and force the lowest supported encryption key length.

Any conforming BR/EDR implementation is expected to be vulnerable to this attack on session key establishment, however, the impact may be limited by refusing access to host resources from a downgraded session, or by ensuring sufficient key entropy to make session key reuse of limited utility to an attacker.

An attacker can take advantage of the shortcomings to brute-force the encryption key in real-time, thereby enabling live injection attacks on traffic between vulnerable peers. The success of the attack, however, presupposes that an attacking device is within the wireless range of two vulnerable Bluetooth devices initiating a pairing procedure and that the adversary can capture Bluetooth packets in plaintext and ciphertext, known as the victim's Bluetooth address, and craft Bluetooth packets.

As mitigations, the Bluetooth Special Interest Group (SIG) recommends that Bluetooth implementations reject service-level connections on an encrypted baseband link with key strengths below 7 octets, have devices operate in “Secure Connections Only Mode” to ensure sufficient key strength, and pair is done via “Secure Connections” mode as opposed to the legacy mode.

The disclosure comes as ThreatLocker detailed a Bluetooth impersonation attack that can abuse the pairing mechanism to gain wireless access to Apple macOS systems via the Bluetooth connection and launch a reverse shell.

It is important for manufacturers to address these architectural vulnerabilities and ensure that security mechanisms and capabilities are implemented in their Bluetooth versions. It is also recommended that users take necessary precautions and follow best practices, such as using secure simple pairing and ensuring that their Bluetooth devices are updated with the latest firmware.

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Frequently Asked Questions

How does the recent Bluetooth security flaw compromise device connections?

The recent Bluetooth security flaw allows attackers to intercept and manipulate data transmitted between two Bluetooth-enabled devices. The attack, known as “adversary-in-the-middle” (AiTM), enables hackers to insert themselves between two connected devices and eavesdrop on communications or inject malicious data.

What steps can users take to protect their devices from Bluetooth-based cyber threats?

To protect their devices from Bluetooth-based cyber threats, users should keep their devices updated with the latest security patches. Additionally, users should only enable Bluetooth when necessary and avoid using public or unsecured Wi-Fi networks. It is also recommended that users avoid pairing their devices with unknown or untrusted devices.

What is the impact of ‘adversary-in-the-middle' attacks on Bluetooth communications?

The impact of AiTM attacks on Bluetooth communications can be severe. Attackers can intercept sensitive information, such as passwords, credit card numbers, and other personal data, without the user's knowledge. Additionally, attackers can inject malicious data into the communication stream, potentially compromising the integrity of the data being transmitted.

In what ways can Bluetooth impersonation attacks be identified and mitigated?

Bluetooth impersonation attacks can be identified and mitigated by using strong authentication mechanisms, such as multi-factor authentication. Additionally, users should be cautious when pairing their devices with unknown or untrusted devices. Developers can also implement additional security measures, such as device fingerprinting and digital signatures, to prevent impersonation attacks.

Are certain Bluetooth versions more susceptible to the new security vulnerabilities?

Yes, certain Bluetooth versions are more susceptible to the new security vulnerabilities. The vulnerabilities affect Bluetooth Core Specification 4.2 to 5.4. Devices running these versions are vulnerable to AiTM attacks.

What measures are developers taking to address Bluetooth protocol weaknesses?

Developers are taking several measures to address Bluetooth protocol weaknesses. These measures include implementing stronger encryption algorithms, improving authentication mechanisms, and implementing additional security measures, such as device fingerprinting and digital signatures. Additionally, developers are working to improve the overall security of Bluetooth-enabled devices by releasing security patches and updates.


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