HOW EASY IS TO HACK?

It's easy to say Russians are hacking the White House and major U.S. companies. It's harder to prove it.

How easy is it to hack?

When cybersecurity firms and U.S. government officials attribute attacks to the Russian government -- or independent hackers operating with Kremlin approval -- the typical evidence they use is pretty circumstantial: A computer virus was written in Russian, created during Moscow working hours and aimed at anti-Russian targets.

Hackers remain anonymous by masking their location, bouncing their computer signals around the world. Hackers who speak one language can write malicious code in another. And they customarily work at odd hours anyway.

"They're just indicators. You never know for sure,"