Bob has been getting warnings that he's "overdrawn" on his MiFi data plan and wants to know if he's been struck by the Heartbleed virus. Leo says no. Heartbleed attacks servers, not mobile devices. More likely, Bob has an app that is active and downloading everything. Someone may have also commandeered the system and is using it.
When Paul is staying at a hotel, he sees other people's libraries when he's on WiFi. Leo says what Paul is seeing is everyone else that's within range of him that's on the same WiFi network. It's a security issue if people aren't aware they're computers are wide open on the network.