Bug puts net's most popular DNS app in Bind

Rare but remote

Makers of Bind have warned of a security vulnerability in versions of the domain name resolution application that could allow attackers to trick servers into returning unauthorized results.

The bug in the Berkeley Internet Name Domain program surfaces only when the DNSSEC security implementation is enabled and the name server accepts queries from the internet at large, a designation known as recursive. The combination of name servers being both recursive and using DNSSEC to validate records is rare, according to this advisory from the Internet Systems Consortium, which maintains Bind.

But DNS servers that are so configured may at risk of attacks that can be remotely launched. "A nameserver with DNSSEC validation enabled may incorrectly add records to its cache from the additional section of responses received during resolution of a recursive client query," ISC representatives wrote.

Bind is the internet's most widely used domain name system software. It is used to translate domain names into numeric IP addresses. DNSSEC is designed to cryptographically authenticate servers that provide DNS look-up information to ensure it is authentic.

Administrators are advised to upgrade Bind to version 9.4.3-P4, 9.5.2-P1, or 9.6.1-P2. There are no fixes for versions 9.0 through 9.3, which are being phased out. Those not able to immediately patch can restrict recursion. ®

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