Washington (CNN)Hackers linked with the governments of China, Iran, North Korea and Turkey have moved to exploit a critical flaw in software used by big tech firms around the world, Microsoft warned late Tuesday. The activity from the foreign hacking groups includes experimentation with the vulnerability, integration into existing hacking tools and “exploitation against targets to achieve the actor’s objectives,” Microsoft said in a blog post . Microsoft did not say which organizations have been targeted by the hackers; a spokesperson could not be immediately reached for comment. It’s the latest fallout from the recently revealed software flaw, which the...