Federal agencies have been asked to download the latest software update by Friday noon.

In response to Microsoft's statement about catching Chinese hackers trying to get access to its Mail and Calendar Server program, called Exchange, US has recently issued an emergency warning to the Chinese Government.

The hackers, as Microsoft says, is a group working for the Chinese Government and spies primarily on American organizations. Microsoft, later, released a software update for Exchange that blocks the hackers, prompting the US cybersecurity, Infrastructure Security Agency, and the CISA to issue an emergency directive that requires all government agencies to update their systems as well.

Although CISA, the US's primary defensive cybersecurity agency, exercises its authority rarely, it said the move was necessary to protect systems from data breach. All federal agencies have been directed to download and install the latest software update by Friday noon.

In another blog post, Microsoft's VP Tom Burt wrote that the hackers had recently targeted different American agencies including law firms, defense contractors, NGOs, policy think tanks, and disease researchers as well.

Contacted via email, a spokesperson at the Chinese Embassy in Washington reiterated the comments of Wang Wenbin. "China has reiterated on multiple occasions that given the virtual nature of cyberspace and the fact that there are all kinds of online actors who are difficult to trace, tracing the source of cyber attacks is a complex technical issue," he said."We hope that relevant media and companies will adopt a professional and responsible attitude and underscore the importance to have enough evidence when identifying cyber-related incidents, rather than make groundless accusations." he further added.

Although there was no news about the hack leading to significant exploitation of the federal computer networks, the announcement is the second time the US has scrambled to address a widespread hacking campaign of foreign government spies.