Here's a list of the US agencies and companies that were reportedly hacked in the suspected Russian cyberattack

• Thousands of companies and US government agencies were at risk of being spied on for months following a sweeping cyberattack reportedly carried out by Russian hackers.
• The full extent of the attack is not yet known, but the list of victims is said to include the Department of Homeland Security and the Pentagon, among others.
• Read below for a list of the government agencies and firms that have reportedly been breached.

A massive cyber attack reportedly executed by a Russian intelligence agency put thousands of companies and US government agencies at risk of being spied on or having data stolen for up to nine months.

The software firm SolarWinds was breached earlier this year when hackers broke into its system and inserted malicious code into one of its software platforms. Customers who updated their software from March to June added the malware to their networks, giving the hackers a backdoor into their systems.

SolarWinds has hundreds of thousands of clients across the globe, including government agencies and most Fortune 500 companies. The company said up to 18,000 of its customers downloaded the software update that contained the malicious code.

Investigating the extent of the cyberattacks may take years, but some organizations have already emerged as compromised, meaning the hackers had potential access to their networks. But it will take long-term investigations for some firms and agencies to determine what data, if any, were stolen or manipulated.

Here's a list of the major US agencies and firms that were reportedly breached:

Department of State

The State Department is among the US agencies said to have been breached, The Washington Post first reported. Russians had also hacked into part of the department's system in 2014.

Department of Homeland Security

Reuters first reported the breach at the Department of Homeland security, the agency responsible for cybersecurity, border security, and, recently, the distribution of the coronavirus vaccine. The department's Cybersecurity and Infrastructure Security Agency also oversaw the secure presidential election last month.

National Institutes of Health

The Post also reported the National Institutes of Health, housed in the Department of Health and Human Services, was also compromised. Reports emerged in the summer that the SVR, a Russian intelligence agency, had targeted the COVID-19 vaccine research.

The Pentagon

Parts of the Pentagon, the headquarters of the Department of Defense, were breached, an unnamed US official reportedly told The New York Times. The official said the extent of the attack was unknown.

Department of Energy

Politico reported the Energy Department, including its National Nuclear Security Administration, was subject to the cyber attack. In a statement, a spokesperson said the breach was "isolated to business networks only," and did not impact national security functions of the department, which includes managing the nuclear weapons stockpile.

Department of the Treasury

The Treasury Department, which manages national finances, was among the first confirmed breaches of the federal government, Reuters reported. Hackers were reportedly spying on internal emails, but the extent of the attack is still unknown.

Department of Commerce

The Commerce Department was also one of the first agencies to have confirmed a breach. Sources told Reuters hackers also appeared to be spying on department emails.

State and local governments

Sources told Bloomberg that up to three state governments were hit by the attack, though they did not name which states. The Intercept reported that the network of the city of Austin, Texas was also breached.

Microsoft

Microsoft confirmed Thursday it was compromised in the cyberattack. Reuters initially reported the breach may have made the tech giant's customers vulnerable, but Microsoft denied this. The company said there is no evidence its products or customer data were targeted.

FireEye

FireEye, one of the world's leading cybersecurity firms, announced on December 8 that its systems had been hacked by a nation-state, marking the first discovery of the sweeping cyberattack.