Tensions have risen in Ukraine this month, as its military has confronted heavily armed, pro-Russian forces that took control of Crimea. But as of now, some of most serious attacks to be alleged are ones hitting websites on both sides of the disagreement.
The strategy the various groups of hackers used was reportedly a distributed denial-of-service attack, a common approach that seeks to overload a server with huge traffic demands from a variety of sources.
Voice of Russia goes on to quote organizers of today's vote, which asks people in Crimea to decide whether to join Russia:
"A new wave of a massive D-Dos attack hit our site at 1 o'clock pm last night.
"Our IT safety experts managed to find out where those attacks came from. It is University of Illinois at Urbana Champaign. The most powerful scanning of servers before the attack was carried out exactly from there."
The agency says of Urbana, "the technological and technical potentialities of this city exceed by thousands of times the needs of its residents."
News of that attack came after NATO reported its main homepage and other websites were attacked Saturday and Sunday.
NATO Spokesperson Oana Lungescu said on Twitter that a "significant DDoS attack" had hit the organization's website. She added that while the attack crippled several websites, it had not affected the integrity of NATO's systems or data. The attack continued into Sunday afternoon, she said.
From German newspaper Deutsche-Welle:
"A Ukrainian group claimed responsibility for the DDoS attacks on the www.cyber-berkut.org website, a claim that could not be verified immediately. The authors, writing in Russian not Ukrainian, said patriotic Ukrainians were angry with NATO for interfering in its affairs."
The newspaper explains that "Berkut" is the name of Ukraine's special police, which was disbanded after President Viktor Yanukovych fled his post and traveled to Russia.
Recent attacks also struck websites in Russia. On Friday, the Kremlin's site was brought down.
From a Reuters report:
"'A powerful cyber attack is under way on the (Kremlin) site,' a spokeswoman for the Russian president's press service said by telephone as security experts struggled to curtail disruption."
Sites of the Central Bank of Russia and the foreign ministry were also attacked Friday, with at least one of those denial-of-service attacks exceeding capacity by more than 10 times, according to the state-run Itar-Tass news agency.
The agency quoted a Kremlin source saying that the attack had nothing to do with events in Crimea.
"Such spamming happens regularly, but to varying degrees of activity. It is not right to link it with developments in Ukraine," the source is quoted as saying.
Some hacking attacks followed an order by Russian regulators Thursday that blocked access to several websites that have criticized President Vladimir Putin and his policies regarding Crimea and the Ukraine.
Russians who tried to access the website Grani.ru, which Radio Free Europe calls "a popular opposition news portal," were met with this message: "Dear users! We apologize, but access to the requested site is restricted."
The top story on the Grani site today describes the referendum in Crimea as taking place under occupation and in violation of Ukraine's constitution.
"Putin has taken the next big step, both in his crackdown on Russian liberty and, possibly, the next phase of his preparations for war on Ukraine," opposition figure and former chess champion Garry Kasparov wrote on his Facebook page. Speaking of his own news portal and several other sites, Kasparov added, "The last source of truth available in Putin's police state is going dark."