Chris Strohm

Bloomberg News

Hillary Clinton’s presidential campaign confirmed Friday that one of its data programs was accessed by hackers, the latest development in what cybersecurity experts call a broad campaign by Russian operatives to infiltrate U.S. political organizations.

“An analytics data program maintained by the DNC, and used by our campaign and a number of other entities, was accessed as part of” a previously disclosed attack on the Democratic National Committee, campaign spokesman Nick Merrill said Friday in an emailed statement. “Our campaign computer system has been under review by outside cyber security experts. To date, they have found no evidence that our internal systems have been compromised.”

The FBI has begun a review of whether the Clinton campaign was hacked, according to a person familiar with the probe who asked not to be identified discussing an internal inquiry.

The campaign’s announcement came hours after the Democratic Congressional Campaign Committee, which raises funds to elect House Democrats, said that it, too, was “the target of a cybersecurity incident.”

Meredith Kelly, press secretary for the organization, said the DCCC was “cooperating with the federal law enforcement agencies with respect to their ongoing investigation.”

Attacks on Democratic organizations, including the DNC, have roiled the 2016 political campaigns. The disclosure by WikiLeaks of purloined party emails forced the head of the DNC to resign as Democrats gathered for their presidential convention. The breach has stirred allegations that Russia is seeking to meddle in the U.S. election, an assertion Russian officials have repeatedly denied.

“Any of the allegations that circulate here in the U.S. about Russia’s involvement are groundless,” Yury Melnik, a spokesman for Russia’s embassy in Washington, said Friday in a phone interview. “There’s no attempts whatsoever to meddle with the political process or the results of the election. The Russian government is ready and willing to work with the current administration and any future administration.”

In a statement Friday, the Federal Bureau of Investigation said it’s “aware of media reporting on cyber intrusions involving multiple political entities, and is working to determine the accuracy, nature and scope of these matters.”

“The cyber threat environment continues to evolve as cyber actors target all sectors and their data,” the agency said. “The FBI takes seriously any allegations of intrusions, and we will continue to hold accountable those who pose a threat in cyberspace.”

The attack on the Democrats’ House campaign committee affected visitors who went to its website from June 19 to June 27, cybersecurity company FireEye Inc. concluded, based on an analysis of internet traffic.

Those visitors were steered to a server controlled by a hacking group known as APT 28,said John Hultquist, FireEye’s manager of cyber espionage intelligence. Other cybersecurity researchers have said APT 28 is an arm of Russia’s military intelligence service GRU, he said.

The DCCC website was altered so that visitors seeking to make a donation were redirected to a server controlled by hackers linked to the Russian government, Hultquist said.The cybersecurity company hasn’t been able to determine if the hackers intercepted the donations or succeeded in planting malware on the computers of those visitors, Hultquist said.

The attack on the DNC resulted in the theft of e-mail and internal reports, some of which have since been published by WikiLeaks. Russia is a leading suspect in that intrusion, according to a U.S. official with knowledge of the probe who asked to not be identified because the inquiry is continuing. Private cybersecurity companies have said they traced the DNC attack to groups in Russia.

DNC Chair Debbie Wasserman Schultz was forced to resign after a firestorm over leaked emails that showed committee staffers favored Clinton and attempted to undermine Senator Bernie Sanders for the Democratic presidential nomination.

In response to speculation that Russia is attempting to influence the outcome of the U.S. presidential race — and might even seek ways to tamper with electronic voting — Eric Schultz, a White House spokesman, said Friday, “As we’ve seen in the past, Russia has tried to influence elections in Europe. We take seriously their past record on this. We also take seriously the integrity of our voting system.”

Clinton adviser Jake Sullivan said Wednesday that the nominee has been briefed on hacking of the DNC and has been told that the weight of expert opinion is that Russia was involved.

“She does not view this as a political issue, she views this as a national security issue,” he told reporters gathered in Philadelphia for this week’s Democratic National Convention. Russia has a history of interfering in elections in other countries, he said.

“Unlike Donald Trump, who praises Putin” and adopts his positions, “Secretary Clinton will stand up to Putin,” Sullivan said.

Trump, the Republican presidential nominee, this week urged Russia to make public “30,000 emails that are missing” from the private server that Clinton maintained when she was secretary of state. He later said he was being “sarcastic.”