The history of Airbus software failures seems limited to CAD/CAM software
http://www.thelightisgreen.com/2007/09/big-it-disaster.html
http://www.bloomberg.com/apps/news?pid=20601085&sid=aSGkIYVa9IZk
From http://www.aviationexplorer.com/Fly_By_Wire_Aircraft.html
...Nonetheless the top concern for computerized, digital fly-by-wire systems is reliability, even more so than for analog systems. This is because a computer running software is often the only control path between the pilot and control surfaces.
If the computer software crashes, the pilot may not be able to control the aircraft. Therefore virtually all fly-by-wire systems are triply or quadruply redundant: they have three or four computers in parallel, and three or four separate wires to each control surface.
If one or two computers crash, the others continue working. In addition most early digital fly-by-wire aircraft also had an analog electric, mechanical or hydraulic backup control system.
The Space Shuttle has, in addition to the redundant set of computers running the primary software, a backup computer running a separately developed, reduced function system that can take over in the event of a fault that affects all of the computers in the redundant set.
This is intended to reduce the risk of total failure due to a generic software fault...
While my earlier post took an immediate turn away from the Airbus crash as terrorist act and focused on the why and who of terrorism, it would not surprise me, especially after reading of the reduncy built into the Airbus, that terrorism was responsible. But like many others here, nothing has convinced me one way or the other.
And no one has convinced me that hacking into any system cannot be done. Unlikely, maybe, in a package like an Airbus but not impossible and if it’s not impossible someone will make an effort.
Just my two cents.