That caution aside, speculation about alien cyberwars takes gigantic leaps in logic that push at the boundary of plausibility.
The aliens would somehow have to glean an intimate knowledge of our computer technology. That's no small trick, unless they can teleport one of our personal computers to their home planet.
What's more, only civilizations orbiting stars within 90 light-years of Earth would even suspect we had a SETI program. That's because it has been less than a century since artificially produced electromagnetic radiation has been leaking off into space from our society.
If we assume that one of these hypothetical nearby civilizations is bent on pulling off an interstellar cyber-terror attack, it could take dozens of years for their signal to reach our radio telescopes at the speed of light. By the time the transmission arrived our computer technology would have substantially evolved from what it is today.
The barriers of time and space ensure a cosmic firewall from cyberattacks.
That is unless the extraterrestrials developed some sort of quantum faster-that-light eavesdropping capability that would allow for their malware to be instantaneously adjusted to blow through the latest Microsoft security update.