LOL, there is no such thing as safe computing, there never will be unless you build you own hardware and write your own entire software stack (including compiler) FROM SCRATCH. This has been known since before outside the military since 1983, as demonstrated by Ken Thompson, with a proof:
Why You Shouldn't Trust Ken Thompson.
Original Paper:
Reflections on Trusting Trust To: what extent should one trust a statement that a program is free of Trojan horses? Perhaps it is more important to trust the people who wrote the software.
He references a much earlier finding about this know flaw, and in virtually every computer system ever produced is vulnerable.