Twitter, The New York Times and other prominent Websites were struck by a powerful cyberattack that continued affecting other Websites into Tuesday evening, directing visitors to a site purportedly controlled by the Syrian Electronic Army (SEA).

The attackers apparently struck an Australian IT services company, Melbourne IT, which provides domain name registration services. The pro-Syrian government SEA has recently conducted several high-profile attacks against media and other Websites.

It appears that the hackers modified master DNS (Domain Name System) entries, allowing them to replace the correct IP addresses for Twitter.com and NYTimes.com with their own, said David Ulevitch, CEO and founder of the security company OpenDNS.

OpenDNS monitors when domains are redirected, and it appeared the attack was continuing into the evening U.S. time, Ulevitch said.

DNS is a distributed address book for Websites. It allows a domain name, such as idg.com, to be translated into an IP addresses that can be called into a browser. Attacks against DNS can be powerful, as it can shift lots of traffic suddenly to a Website controlled by an attacker, which could then pose further risk for visitors inadvertently pushed there.

The Twitter.com and NYTimes.com domains are listed as being registered with Melbourne IT, according to “whois,” the domain name registration database.

Redirecting The New York Times’ domain name also means email to and from the company could have been redirected to the server controlled by the attacker.

As a domain name registrar, Melbourne IT holds the master DNS record, Ulevitch said. It would appear that the affected sites, some of which were listed by security vendor AlienVault Labs, have their master DNS records with Melbourne IT.

There are a few ways hackers could modify a DNS record. A hacker could obtain the access credentials needed to modify an organization’s DNS record with a registrar such as Melbourne IT. Ulevitch said that kind of hack is unlikely in this case since so many Websites were redirected.

It is more likely that the attackers gained access to Melbourne IT’s infrastructure, he said. Melbourne IT officials could not be immediately reached on Wednesday morning.

Beyond pranks

DNS hacks can have other serious consequences. Redirecting The New York Times’ domain name also means email to and from the company could have been redirected to the server controlled by the attacker.

“If you’re a confidential source for The New York Times and sending an email that’s rerouted to another mail server, you’ve just blown your cover,” Ulevitch said.

In a news story, the newspaper wrote that “the attack also forced employees of The Times to take care in sending emails.”

Also, the Website that people are being redirected to could also be engineered to check if visitors have unpatched software vulnerabilities that could be used to infect their computers with malware.

Since the Websites in this attack have high traffic, “you can infect millions of people in minutes,” Ulevitch said.

The SEA’s Website is based in Russia, said Jamie Blasco, director of AlienVault. That Website was not responding, which was likely the result of an overwhelming amount of redirected traffic. The SEA could not immediately be reached for comment.

Eileen M. Murphy, vice president of corporate communications for the New York Times, said the newspaper’s Website appeared down to people browsing from within the U.S. but was working for those outside the country.

“We’re working on resolving it as we speak,” Murphy said.

Twitter said one of its domains used for serving images, twimg.com, was affected starting at 20:49 UTC and disrupted the viewing of some images. The domain was restored at 22:29 UTC, Twitter wrote in a service update.

“No Twitter user information was affected by this incident,” the company said.