Users first began complaining of slow response times at the end of May, according to online bulletin boards. Some users also complained that their Web queries were being redirected to other sites. Many of those queries ended up at the same advertising site, which suggests a DNS compromise, according to a blog by Rik Ferguson, a security researcher at Trend Micro.
Complaints from Eircom users reportedly intensified at the beginning of July, and last week the ISP issued a statement that confirmed the problem:
"Customers may have recently experienced delays in web browsing and may have been unable to access the Internet," the statement said. "In some cases, customers may have been redirected to incorrect Websites. This issue has been caused by an unusual and irregular volume of internet traffic being directed onto our network, and this impacted the systems and servers that provide access to the Internet for our customers.
"Eircom is working continuously to minimize the impact for customers and has taken a number of steps, including software updates and hardware interventions, to fully restore Internet service."
But this week, users again are reporting problems using the ISP's services. In a second statement issued July 14, the ISP conceded that the problem may be a second attack. "While it is too early to confirm, Eircom believes that [this week's performance issues are] related to an unprecedented volume of traffic deliberately directed at our network which has caused difficulties for customers over recent days," the company says.
Eircom stopped short of discussing the actual nature of the attacks, but both Ferguson's blog and multiple bulletin board users are reporting that the performance problems and site redirections can be mitigated if users switch to another Domain Name Server (DNS) service, such as OpenDNS. These reports provide further evidence that Eircom has become the victim of DNS poisoning, possibly more than once.
The problems at Eircom reinforce the need for a solution to the DNS vulnerabilities that came to light two years ago, necessitating an industrywide patching effort, researchers say. Many ISPs and large enterprises are moving to DNS SEC, which may help alleviate the problem, they say.
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