The Trump Organisation denied the domain names were ever compromised. But a review of internet records by the AP and cybersecurity experts shows otherwise.
And it was not until this past week, after the Trump camp was asked about it by the AP, that the last of the tampered- with addresses were repaired.
A further mystery is who the hackers were and why they did it. The discovery represents a new twist in the Russian hacking story, which up to now has focused mostly on what US intelligence officials say was a campaign by the Kremlin to try to undermine Democrat Hillary Clinton's candidacy and benefit Trump's.
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The affected addresses, or domain names, included donaldtrump.org, donaldtrumpexecutiveoffice.com, donaldtrumprealty.com and barrontrump.com.
They were compromised in two waves of attacks in August and September 2013, according to the review of internet records.
Many of the addresses were not being used by Trump. Businesses and public figures commonly buy addresses for possible future use or to prevent them from falling into the hands of rivals or enemies. The Trump Organization and its affiliates own at least 3,300 in all.
Computer users who entered or clicked on one of those Trump addresses probably would have had no idea they were redirected to servers in Russia.
Within days after the AP asked the Trump Organization about the tampering, the affected web addresses were all corrected.
GoDaddy spokesman Nick Fuller said the company had no breaches of its system in 2013 and has measures in place to monitor for malicious activity. Fuller would not discuss any customers in particular.
Some cybersecurity experts said there is an outside chance the tampering was a probe, an attempt to test security for an eventual effort to gather information on Trump or his business dealings. But those experts were only guessing.
There was no evidence the hackers ultimately broke into server computers at the Trump Organization or other Trump interests.
Vixie said the Trump Organization's apparent failure to detect what was happening probably suggests inadequate cybersecurity at the company.
"There's no way something like this could go by in the Bloomberg empire without this being seen," Vixie said.