Learning from Prism in US, I think it&#x27;s highly possible. 
Remember the state also has control over ISPs and internet access. They can inject binary into files you download.
It is very unlikely that you operate in an air-gapped computer.
I&#x27;ve been learning some reverse engineering lately and the possibilities for injecting malicious code seem endless.
If such a practice happens, people will have to live in paranoia.