Internal security measures used by the Republican National Committee blocked Russian hackers from penetrating the organization's computer networks with phishing emails, keeping the RNC from being susceptible to the same types of techniques employed to hack the Democratic National Committee.
U.S. officials briefed on the matter said that Russian intelligence tried to gain access to the RNC's system but failed, unlike the DNC where hackers successfully breached its networks, the Wall Street Journal reported Friday.
An email filter meant to detect spam and potentially malicious traffic flagged the phishing emails sent by hackers before they reached their intended recipient. U.S. officials said that the methods utilized to target RNC officials were much less aggressive than those used against the DNC.
The news comes amid a national debate over the role of Russian influences on election-related hacks, the Journal noted.
The Central Intelligence Agency has concluded that Russian hackers, whom analysts say work for that country's military and intelligence apparatus, stole emails from the DNC, as well as another Democratic organization and the chairman of Hillary Clinton's presidential campaign, to harm her candidacy and boost Republican Donald Trump's chances of winning. Russia has denied the allegations.
The possibility that Russians tried and failed to infiltrate the RNC doesn't necessarily conflict with the CIA's conclusion. A senior U.S. official said analysts now believe what started as an information-gathering campaign aimed at both parties later took on a focus of leaked emails about Mrs. Clinton and Democrats.
President Obama promised Thursday that the United States would retaliate against the Russians for their role in the hacks.
President-elect Donald Trump has castigated reports that Russia directed and executed hacks targeting the DNC and Clinton campaign officials to help his White House run, calling them "ridiculous."
Unlike the DNC, RNC officials called in a security review as soon as they became aware of the hacking attempt, the Journal reported.
RNC officials, concerned they too might have been compromised, called a private computer security firm, which in turn called the FBI and obtained information about what kinds of malicious emails to look for, the person said. Upon inspection, the RNC found that its electronic filters had blocked emails sent to a former employee matching the description they'd been warned about.
It was reported earlier this week that DNC officials failed to notify superiors when they were first contacted by the FBI about possible hacking attempts.
The DNC data breach marks the second time in 44 years that the organization has been the subject of a break-in. The DNC's headquarters were infamously broken into by individuals working on behalf of President Richard Nixon during the 1972 presidential campaign.