Bug 987869 (CVE-2016-6171) - VUL-0: CVE-2016-6171: knot: malicious primary DNS servers can crash secondaries
Summary: VUL-0: CVE-2016-6171: knot: malicious primary DNS servers can crash secondaries
Status: RESOLVED WONTFIX
Alias: CVE-2016-6171
Product: SUSE Security Incidents
Classification: Novell Products
Component: Incidents (show other bugs)
Version: unspecified
Hardware: Other openSUSE 42.1
: P3 - Medium : Major
Target Milestone: ---
Assignee: Petr Gajdos
QA Contact: Security Team bot
URL:
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Blocks:
 
Reported: 2016-07-06 12:28 UTC by Andreas Stieger
Modified: 2016-08-04 07:54 UTC (History)
2 users (show)

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Found By: Security Response Team
Services Priority:
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Blocker: ---
Marketing QA Status: ---
IT Deployment: ---

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Description Andreas Stieger 2016-07-06 12:28:18 UTC 
via oss-sec http://seclists.org/oss-sec/2016/q3/19

"most DNS server implementations do not implement reasonable restrictions for zone sizes. This allows an explicitly configured primary DNS server for a zone to crash a secondary DNS server, affecting service of other zones hosted on the same secondary server."

from https://lists.dns-oarc.net/pipermail/dns-operations/2016-July/015058.html

> * [ For [LT] Secondary DNS Service ]
> 
>   See https://github.com/sischkg/xfer-limit
> 
>   Most of authoritative DNS server softwares do not have size limit of
>   zone transfer. He generated unlimited zone information at master
>   server, and transfered to slave servers. BIND 9, knot DNS and Power
>   DNS slave servers received unlimited zone informataion and died.
>   NSD slave DNS server received unlimited zone data and /tmp became full.
> 
>   He generated zone transfer size limit patch for BIND 9, Knot, NSD,
>   PowerDNS.

Third party patches at https://github.com/sischkg/xfer-limit

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-6171
http://seclists.org/oss-sec/2016/q3/20
Comment 1 Andreas Stieger 2016-07-06 12:31:42 UTC 
openSUSE only.
Comment 2 Swamp Workflow Management 2016-07-06 22:00:38 UTC 
bugbot adjusting priority
Comment 3 Petr Gajdos 2016-08-04 07:54:48 UTC 
According to upstream and maintainer for opensuse (Ondrej Sury), this does not deserve attention it has (and should not have a CVE assigned).

'We believe that master and slave servers should have appropriate trust
relationship.' [1]

The bug is more like feature request and, if you want, feed it trough fate and we can consider update to 1.6.8 as soon as it is out.

[1] https://lists.nic.cz/pipermail/knot-dns-users/2016-July/000915.html