In a filing with the Securities and Exchange Commission, FireEye said it believes the attack was state-sponsored given its characteristics and were “different from the tens of thousands of incidents we have responded to throughout the years,” and “used a novel combination of techniques not witnessed by us or our partners in the past.”

The breach accessed the company’s “Red Team” assessment tools that FireEye uses to test a client’s cybersecurity.

“These tools mimic the behavior of many cyber threat actors and enable FireEye to provide essential diagnostic security services to our customers,” the company said in the filing. “Consistent with our goal to protect the community, we are proactively releasing methods and means to detect the use of our stolen Red Team tools.”

In its investigation to date, FireEye said it does not appear that customer data was accessed. If customer data is found to be compromised, FireEye said it will contact the customer directly.

Most recently, FireEye was in the news as one of the big stocks that Republican Sen. David Perdue of Georgia reportedly bought and sold while he was a member of the Senate’s subcommittee on cybersecurity,

In November, FireEye shares gained ground on an announcement that Blackstone Group Inc. BX, +0.76% made a significant investment in the company. In October, the company reported record earnings amid “an escalation of cyberattacks.” That was just prior to a warning from U.S. officials that Russian hackers have been targeting state and local governments.

Back in March, FireEye told MarketWatch that Iran-backed hackers had “the most active” over the past 12 months.

At Tuesday close, shares of FireEye were down 6% for the year, versus a 28% gain on the ETFMG Prime Cyber Security ETF HACK, +1.48%, a 15% gain on the S&P 500 index SPX, +0.28%, and a 40% surge in the Nasdaq Composite Index COMP, +0.50%.