Why doesnt she have a firewall or antivirus for this sorta stuff

Zero day exploit?

Kind of, yeah, it's a work around that a lot of pirates and hackers have figured out but most of the solutions are too complicated or expensive for companies to be willing to risk it.

Basically the station has to plot incoming ship flight paths. Most of them do this by receiving data from the incoming ship that describes the planned flight path and then includes updates as the path changes or is executed. The virus makes use of the fact that the bulk of antivirus suites only check the initial signal for viruses and once that signal is confirmed it green-lights all comms from that same ship so that emergency updates won't get delayed by the check. So the virus was transmitted as a packet of updates to the incoming trajectories.

She does, in fact she has a pretty good electronic warfare system. But you know how it is, as soon as someone makes a security system someone makes a way to get around it.