[arch-security] [ASA-201507-6] bind: denial of service

[Remi Gacogne]

Arch Linux Security Advisory ASA-201507-6
=========================================

Severity: High
Date    : 2015-07-07
CVE-ID  : CVE-2015-4620
Package : bind
Type    : denial of service
Remote  : Yes
Link    : https://wiki.archlinux.org/index.php/CVE

Summary
=======

The package bind before version 9.10.2.P2-1 is vulnerable to denial of
service.

Resolution
==========

Upgrade to 9.10.2.P2-1.

# pacman -Syu "bind>=9.10.2.P2-1"

The problem has been fixed upstream in version 9.10.2.P2.

Workaround
==========

Disabling DNSSEC validation prevents exploitation of this defect but is
not generally recommended. The recommended solution is to upgrade to a
patched version. DNSSEC validation can be disabled by setting

dnssec-validation no;

in the "options" section of /etc/named.conf

Description
===========

A very uncommon combination of zone data has been found that triggers a
bug in BIND, with the result that named will exit with a "REQUIRE"
failure in name.c when validating the data returned in answer to a
recursive query.

This means that a recursive resolver that is performing DNSSEC
validation can be deliberately stopped by an attacker who can cause the
resolver to perform a query against a maliciously-constructed zone.

Impact
======

A remote attacker can crash a bind resolver performing DNSSEC validation
by querying it for a specially crafted zone.

References
==========

https://kb.isc.org/article/AA-01267/
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-4620

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