They use the same broken software we all do. ssh, written in C. Perforce, written in C. Find a single memory management error in one of those programs, and Google's source code is yours.
Furthermore, they have people programming. This is the biggest security hole and every company suffers/will suffer from it.
huh? you'll need to get behind corporate firewall first. And this is non-trivial part. Once you inside, it may be easier to just get this particular bit of source code from incorrectly secured employee's computer.
So you feel that ssh should be written in Perl?
That's a disingenuous way to say c is a fine language for ssh.