There are many reasons why hackers might want to get into a big tech company’s systems.

Big tech companies like Intel and Nvidia had their computers hacked, along with the departments of the US federal government, in the SolarWinds hack.

SAN FRANCISCO (Reuters)-Microsoft Corp said on Thursday it found malicious software in its systems related to a massive hacking campaign disclosed by U.S. officials this week, adding a top technology target to a growing list of attacked government agencies.

The Redmond, Washington company is a user of Orion, the widely deployed networking management software from SolarWinds Corp which was used in the suspected Russian attacks on vital U.S. agencies and others.

Microsoft also had its own products leveraged to attack victims, said people familiar with the matter. The U.S. National Security Agency issued a rare “cybersecurity advisory” Thursday detailing how certain Microsoft Azure cloud services may have been compromised by hackers and directing users to lock down their systems.

Microsoft wants you to know this hack is even bigger than you think.

Microsoft president Brad Smith warned that the wide-ranging hack of the SolarWinds’ Orion IT software is “ongoing,” and that investigations reveal “an attack that is remarkable for its scope, sophistication and impact.” The breach targeted several US government agencies and is believed to have been carried out by Russian nation-state hackers.

Smith characterized the hack as “a moment of reckoning” and laid out in no uncertain terms just how large and how dangerous Microsoft believes the hack to be. It “represents an act of recklessness that created a serious technological vulnerability for the United States and the world,” Smith argues.

He believes that it “is not just an attack on specific targets, but on the trust and reliability of the world’s critical infrastructure in order to advance one nation’s intelligence agency.” Though the post stops short of explicitly accusing Russia, the implication is very clear. “The weeks ahead will provide mounting and we believe indisputable evidence about the source of these recent attacks,” according to Smith.

As the U.S. government works to contain a sprawling hacking campaign that relies on software in technology from SolarWinds, a federal contractor, technology firms are disabling some of the hackers’ key infrastructure.

Cybersecurity giant FireEye on Wednesday said that it had worked with Microsoft and the domain registrar GoDaddy to take over one of the domains that attackers had used to send malicious code to victim machines. The move is no panacea for stopping the suspected state-sponsored hacking campaign, though it could help stem the tide of victims, which reportedly includes the departments of Treasury and Homeland Security.

The seized domain, known as a “killswitch,” will “affect new and previous” infections of the malicious code coming from that particular domain, FireEye said in a statement that was first reported by independent journalist Brian Krebs. “Depending on the IP address returned when the malware resolves avsvmcloud[.]com, under certain conditions, the malware would terminate itself and prevent further execution.”