Bluetooth devices are suspected of being targeted by a Bluesnarfing attack.

Bluesnarfing is a Bluetooth attack described in CEH v13 Wireless Network Hacking, where attackers exploit misconfigured Bluetooth devices to access sensitive data such as contacts, messages, and files—often without user interaction.

One of the most critical enablers of Bluesnarfing is Bluetooth discoverable mode. When devices are discoverable, attackers can easily identify them and attempt unauthorized connections or exploit vulnerabilities in Bluetooth services.

Disabling discoverable mode significantly reduces the attack surface by preventing unauthorized devices from locating Bluetooth-enabled systems. CEH v13 explicitly recommends setting Bluetooth devices to non-discoverable mode when not pairing.

While firmware updates (Option B) are important, they do not immediately prevent discoverability-based attacks. Stronger PINs (Option C) help against pairing attacks but do not stop unauthorized queries. Network-level encryption (Option D) is inherent in Bluetooth protocols and does not mitigate discovery abuse.

CEH v13 highlights that visibility control is the most immediate and effective defense against Bluesnarfing. Therefore, Option A is the correct answer.