What was actually hacked

Orion, a popular network management software from SolarWinds, was infiltrated by hackers, who many suspect to be associated with the Russian government. The company self-reported the potential breach Monday to federal regulators, one day after alerting 33,000 customers of the hack. In total, the actual number of customers affected may be closer to 18,000.

In the filing, SolarWinds said the "cyberattack" was likely the work "of a highly sophisticated, targeted … attack by an outside nation state," although that hasn't been confirmed yet.

It also isn't clear yet to SolarWinds or its customers what data was actually accessed in the hack, only that a "vulnerability" in the software was created to help gain access without being detected between March and June. The FBI and other federal intelligence agencies are involved in the investigation, according to the company's filing.

What is SolarWinds?

SolarWinds makes "IT look easy," or at least that's how the company describes itself online. The business provides IT infrastructure management software and IT operational support.

The international company is headquartered in Southwest Austin, but its 3,200 employees and 300,000 customers span the globe. So SolarWinds may not be a household name, but its reach and reputation make it well-known in information technology circles.

According to Fortune, SolarWinds serves the U.S. military as well as the majority of all Fortune 500 companies. That means the hack itself could have wider-ranging implications beyond the federal security concerns.

Unsurprisingly, the publicly-traded company has seen its stock value plummet to the lowest of levels since SolarWinds went public in late 2018. SolarWinds is urging its customers of the popular software to follow through measures outlined in a security advisory.

Reactions so far this week

Cybersecurity experts are sounding the warning alarms. CNN Business talked to one expert who said the unknowns surrounding this hack has them particularly concerned. A former NSA hacker even called out SolarWinds on Twitter, disputing information contained in the company's public filing.

The Commerce, Homeland Security and Agriculture departments were all targeted, but military and national security operations might have been accessed, too. And that access might've been unfiltered if hackers were able to indeed open the so-called "God door," one former White House official warned about Wednesday.

Data was stolen from at least one company, cybersecurity firm FireEye, which had security assessment tools stolen as part of a hack that prompted this entire discovery. And the attack is daunting enough that one of the senior-most members of Congress, U.S. Sen. Dick Durbin, D-Illinois, called the attack "virtually a declaration of war" by Russia.