A new serious DOS flaw affects BIND DNS software, updates it now

A new serious denial-of-service (DoS) vulnerability was patched this week by the Internet Systems Consortium (ISC) in the BIND DNS software.

A security serious denial-of-service (DoS) vulnerability, tracked as CVE-2017-3135, was patched this week by the Internet Systems Consortium (ISC) in the BIND DNS software.

The vulnerability in the BIND DNS software was reported by Ramesh Damodaran and Aliaksandr Shubnik of Infoblox.

The DoS flaw affects BIND 9.8.8, all 9.9 releases since 9.9.3, all 9.10 releases, and all 9.11 version.

The flaw has been patched with the release of versions 9.9.9-P6, 9.10.4-P6 and 9.11.0-P3.

The flaw, rated as “high severity” (CVSS score of 7.5), is remotely exploitable in the case of servers uses certain configurations.

“Some configurations using both DNS64 and RPZ can lead to an INSIST assertion failure or a NULL pointer read; in either case named will terminate.” reads the advisory published by the ISC

“Under some conditions when using both DNS64 and RPZ [Response Policy Zones] to rewrite query responses, query processing can resume in an inconsistent state leading to either an INSIST assertion failure or an attempt to read through a NULL pointer,”

Only servers utilizing both DNS64 and RPZ at the same time are potentially vulnerable.

“When this condition occurs, it will result in either an INSIST assertion failure (and subsequent abort) or an attempt to read through a NULL pointer. On most platforms a NULL pointer read leads to a segmentation fault (SEGFAULT), which causes the process to be terminated,” ISC added.

The advisory suggests to update each vulnerable installation, it also includes possible workarounds such as removing either DNS64 or RPZ from the configuration, or restricting the contents of the policy zone.

In January 2017, the Internet Systems Consortium (ISC) has issued updates to solve four high severity flaws in the DNS software BIND. The flaw could be exploited by a remote attacker to cause a DoS condition.

An attacker can exploit the vulnerabilities to cause the BIND name server process to encounter an assertion failure and stop executing.

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Pierluigi Paganini

(Security Affairs – BIND DNS software, security)

Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.