DNS loophole could allow hackers to carry out “nation-state level spying”

Security researchers have discovered a flaw within major DNS-as-a-Service (DNSaaS) providers that could allow hackers to access confidential data within corporate networks.

Shir Tamari and Ami Luttwak, researchers at cyber security firm Wiz, found a loophole that allowed them to intercept a portion of worldwide dynamic DNS traffic going through managed DNS providers like Amazon and Google.

“Essentially, we “wiretapped” the internal network traffic of 15,000 organizations (including Fortune 500 companies and government agencies) and millions of devices,” said Tamari.

“It was a bottomless well of valuable intel - computer names, employee names and locations, and details about organizations’ web domains including entry points that are exposed to the internet.”

He added that there is no way of knowing whether hackers have already exploited the loophole and collected data undetected for over a decade. Leaked information from the flaw can contain internal and external IP addresses, computer names, and, sometimes, NTLM / Kerberos tickets.

“The root cause of the problem is the non-standard implementation of DNS resolvers that, when coupled with specific unintended edge cases on the DNS service provider's side, cause major information leakage from internal corporate networks,” said Tamari.

In a presentation at this year’s Black Hat conference in Las Vegas, researchers showed how Microsoft Windows endpoints revealed sensitive customer information when performing DNS update queries.

“The security risk is high. If an organization's DNS Updates are leaked to a malicious 3rd party, they reveal sensitive network information that can be used to map the organization and make operational goals,” added the researchers.

Internal IP addresses reveal the organization’s network segments; computer names hint at the potential content they may hold; external IP addresses expose geographical locations and the organization's sites throughout the world; and internal IPv6 addresses are sometimes accessible from the outside and allow an entry point into the organization, according to researchers.

“The impact is huge. Out of six major DNSaaS providers we examined, three were vulnerable to nameserver registration,” said Tamari.

Researchers added that any cloud provider, domain registrar, and website host who provides DNSaaS could be vulnerable. Tamari said that while two major DNS providers (Amazon and Google) have fixed the issue, others may still be vulnerable. “As a result, millions of devices are potentially vulnerable,” he said.