81 lines
3.1 KiB
XML
81 lines
3.1 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<?xml-stylesheet href="/xsl/glsa.xsl" type="text/xsl"?>
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<?xml-stylesheet href="/xsl/guide.xsl" type="text/xsl"?>
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<!DOCTYPE glsa SYSTEM "http://www.gentoo.org/dtd/glsa.dtd">
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<glsa id="200708-13">
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<title>BIND: Weak random number generation</title>
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<synopsis>
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The ISC BIND random number generator uses a weak algorithm, making it
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easier to guess the next query ID and perform a DNS cache poisoning attack.
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</synopsis>
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<product type="ebuild">bind</product>
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<announced>August 18, 2007</announced>
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<revised>August 18, 2007: 01</revised>
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<bug>186556</bug>
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<access>remote</access>
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<affected>
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<package name="net-dns/bind" auto="yes" arch="*">
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<unaffected range="ge">9.4.1_p1</unaffected>
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<vulnerable range="lt">9.4.1_p1</vulnerable>
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</package>
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</affected>
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<background>
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<p>
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ISC BIND is the Internet Systems Consortium implementation of the
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Domain Name System (DNS) protocol.
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</p>
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</background>
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<description>
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<p>
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Amit Klein from Trusteer reported that the random number generator of
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ISC BIND leads, half the time, to predictable (1 chance to 8) query IDs
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in the resolver routine or in zone transfer queries (CVE-2007-2926).
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Additionally, the default configuration file has been strengthen with
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respect to the allow-recursion{} and the allow-query{} options
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(CVE-2007-2925).
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</p>
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</description>
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<impact type="normal">
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<p>
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A remote attacker can use this weakness by sending queries for a domain
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he handles to a resolver (directly to a recursive server, or through
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another process like an email processing) and then observing the
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resulting IDs of the iterative queries. The attacker will half the time
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be able to guess the next query ID, then perform cache poisoning by
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answering with those guessed IDs, while spoofing the UDP source address
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of the reply. Furthermore, with empty allow-recursion{} and
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allow-query{} options, the default configuration allowed anybody to
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make recursive queries and query the cache.
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</p>
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</impact>
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<workaround>
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<p>
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There is no known workaround at this time for the random generator
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weakness. The allow-recursion{} and allow-query{} options should be set
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to trusted hosts only in /etc/bind/named.conf, thus preventing several
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security risks.
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</p>
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</workaround>
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<resolution>
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<p>
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All ISC BIND users should upgrade to the latest version:
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</p>
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<code>
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# emerge --sync
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# emerge --ask --oneshot --verbose ">=net-dns/bind-9.4.1_p1"</code>
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</resolution>
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<references>
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<uri link="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2925">CVE-2007-2925</uri>
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<uri link="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-2926">CVE-2007-2926</uri>
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</references>
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<metadata tag="requester" timestamp="Sun, 05 Aug 2007 10:40:49 +0000">
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aetius
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</metadata>
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<metadata tag="submitter" timestamp="Mon, 13 Aug 2007 23:06:16 +0000">
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falco
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</metadata>
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<metadata tag="bugReady" timestamp="Tue, 14 Aug 2007 23:00:40 +0000">
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falco
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</metadata>
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</glsa>
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