Twitter later reported that its DNS records, not its servers, had instead been temporarily compromised. "As some noticed, Twitter.com was redirected for a while but API and platform applications were working. We will update with more information and details once we've investigated more fully," read Twitter's blog post.
Security experts say it appears to have been a DNS hijacking attack and was mostly used for hacktivism. Twitter users were just redirected to the hacktivists' site, but it could have been much worse. "These sorts of attacks are usually limited to hacktivism activities like this one today, but imagine the potential to criminals if they could pull this off against any site requiring log in credentials, such as PayPal, eBay, MSN, Facebook," blogged Rik Ferguson, solutions architect for Trend Micro. "One has to wonder how quickly the attack would be noted if the dummy site was an exact replica of the victim and was simply there to harvest credentials and redirect the user then into the real site."
Beth Jones, security analyst at Sophos, says the "Iranian Cyber Army" site contained no malware, and it's very likely that Twitter's servers remained untouched in the attack. "It looks like they just hacked the registrar to redirect traffic," says Jones, who notes that Sophos sees a new Website compromise every 3.6 seconds.
Just how the hackers changed the DNS records for twitter.com remains a mystery. And apparently Twitter was just one site affected by the compromise. Trend Micro's Ferguson says he found via a search other Websites displaying the same content.
Gary Warner, director of research in computer forensics at the University of Alabama at Birmingham, blogged today that it appears the hosting company for the DNS servers, BlueHost, may have been compromised. "In my opinion, it looks like that server was compromised via WordPress vulnerabilities, but that is just an educated guess based on content at this time. So, it looks like the hacker first hacked one of the sites on the Bluehost box, other mowjcamp.org, wpcrowd.com, or coventryri.com, then redirected all the twitter traffic to that IP by changing the Nameserver entries for Twitter to point away from their normal Google-provided IP addresses to 18.104.22.168 instead," he blogged.
But Rod Rasmussen, president at Internet Identity, says his firm watched the attackers move the redirect from server to server several times, so it was not just BlueHost servers that were affected. Rasmussen says it appears the attackers had a user name and password for a DynDNS account, from which they changed the DNS record resolution for Twitter.
"On the face of it, it seems more like hacktivism. But it could be a cover for doing something more -- it's hard to tell," he says.
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