You are a cybersecurity consultant at FortiSec, advising DesertTech Innovations in Phoenix, Arizona.

The requirements map most directly to WPA3, because WPA3-Personal replaces the legacy WPA2-PSK handshake with SAE (Simultaneous Authentication of Equals). SAE is designed to resist offline dictionary attacks: even if an attacker captures the handshake, they cannot simply take it offline and test password guesses at high speed the way they can with WPA2-PSK handshakes. This directly addresses management’s concern that a captured handshake plus a weak passphrase could enable offline cracking and eventual session key recovery.

WPA3 also strengthens per-session protection by improving how keys are established and by supporting stronger cryptographic defaults. In enterprise contexts, WPA3 aligns with stronger authentication and encryption suites, and in IoT scenarios it supports modern onboarding and improved security posture compared to older WPA2/TKIP-era configurations. The “per-session encryption” and “stronger protection” goals are consistent with WPA3’s modern design focus.

Why the other options are less suitable:

MAC address filtering (A) is not a security control against credential capture or offline attacks; MACs are easily spoofed and do not provide cryptographic protection.

802.1X authentication (B) (WPA2/WPA3-Enterprise) is very strong and removes reliance on a single shared PSK by using per-user/device credentials and dynamic keys. However, the question’s key requirement explicitly calls out preventing offline dictionary attacks even if a handshake is captured—this is most directly the hallmark improvement of WPA3-Personal (SAE). (In practice, WPA3-Enterprise with 802.1X is also excellent, but “upgrade to WPA3” is the single best match to the stated offline dictionary concern.)

Disabling TKIP (D) is good hygiene (prefer AES/CCMP), but it does not prevent WPA2-PSK handshake capture and offline cracking if PSK is used.

Therefore, the best measure to meet the stated modernization goals is C. Upgrade to WPA3.