Bug 1779566 (CVE-2019-19331) - CVE-2019-19331 knot-resolver: DNS packets taking few seconds to process with full CPU utilization leads to DoS
Summary: CVE-2019-19331 knot-resolver: DNS packets taking few seconds to process with ...
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2019-19331
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1780511 1780513
Blocks:
TreeView+ depends on / blocked
 
Reported: 2019-12-04 09:36 UTC by msiddiqu
Modified: 2019-12-06 13:04 UTC (History)
4 users (show)

Fixed In Version: knot-resolver 4.3.0
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2019-12-06 13:04:53 UTC


Attachments (Terms of Use)
big-rrset.patch (14.55 KB, patch)
2019-12-04 10:00 UTC, msiddiqu
no flags Details | Diff
cname-limit.patch (3.30 KB, patch)
2019-12-04 10:00 UTC, msiddiqu
no flags Details | Diff

Description msiddiqu 2019-12-04 09:36:34 UTC
DNS replies with very many resource records might be processed very inefficiently, in extreme cases taking even several CPU seconds for each such uncached message.  For example, a few thousand A records can be squashed into one DNS message (limit is 64kB).

To execute an attack it is enough to:
+ own a rogue authoritative server or utilize an existing name with a huge RRset, and
+ trigger DNS query for that name from the resolver to be attacked

References: 

https://gitlab.labs.nic.cz/knot/knot-resolver/tags/v4.3.0

Comment 1 msiddiqu 2019-12-04 09:56:37 UTC
From upstream:

Most of the issue can be mitigated by updating libknot dependency to >= 2.9.1. Otherwise a complete fix will be released in Knot Resolver 4.3.0, which also does not require libknot update. The attached patches are applicable to recent releases (when doc diff is stripped).

Comment 2 msiddiqu 2019-12-04 10:00:22 UTC
Created attachment 1641993 [details]
big-rrset.patch

Comment 3 msiddiqu 2019-12-04 10:00:58 UTC
Created attachment 1641994 [details]
cname-limit.patch

Comment 5 Dhananjay Arunesh 2019-12-06 09:04:18 UTC
Created knot-resolver tracking bugs for this issue:

Affects: fedora-all [bug 1780511]

Comment 6 Dhananjay Arunesh 2019-12-06 09:04:51 UTC
Created knot-resolver tracking bugs for this issue:

Affects: epel-7 [bug 1780513]

Comment 7 Product Security DevOps Team 2019-12-06 13:04:53 UTC
This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.


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