Bug 1397345 – CVE-2016-7426 ntp: Client rate limiting and server responses

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Bug 1397345 - (CVE-2016-7426) CVE-2016-7426 ntp: Client rate limiting and server responses

Summary:	CVE-2016-7426 ntp: Client rate limiting and server responses

Status:	CLOSED ERRATA

Aliases:	CVE-2016-7426

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=moderate,public=20161121,repor...
Keywords:	Security

Depends On:	1397351 1411642 1411643 1411644 1411645
Blocks:	1397349
	Show dependency tree / graph

Reported:	2016-11-22 05:56 EST by Adam Mariš
Modified:	2017-02-06 01:50 EST (History)
CC List:	6 users (show)

See Also:
Fixed In Version:	ntp-4.2.8p9
Doc Type:	If docs needed, set a value
Doc Text:	It was found that when ntp is configured with rate limiting for all associations the limits are also applied to responses received from its configured sources. A remote attacker who knows the sources can cause a denial of service by preventing ntpd from accepting valid responses from its sources.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2017-02-06 01:50:32 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2017:0252	normal	SHIPPED_LIVE	Moderate: ntp security update	2017-02-06 06:16:56 EST

Groups: None (edit)

Description Adam Mariš 2016-11-22 05:56:41 EST

When ntpd is configured with rate limiting for all associations (restrict default limited in ntp.conf), the limits are applied also to responses received from its configured sources. An attacker who knows the sources (e.g., from an IPv4 refid in server response) and knows the system is (mis)configured in this way can periodically send packets with spoofed source address to keep the rate limiting activated and prevent ntpd from accepting valid responses from its sources.

External References:

http://support.ntp.org/bin/view/Main/NtpBug3071

Comment 1 Adam Mariš 2016-11-22 06:09:12 EST

Created ntp tracking bugs for this issue:

Affects: fedora-all [bug 1397351]

Comment 2 Huzaifa S. Sidhpurwala 2016-12-14 03:14:56 EST

Mitigation:

If you choose to use restrict default limited ..., be sure to use restrict source ... (without limited) to avoid this attack.

Comment 4 Keyur Pujara 2017-01-16 06:30:27 EST

Is an RPM released with fix for this. I haven't seen one @ http://mirror.centos.org. 

If not released, what is ETA for same?

Thanks, Keyur

Comment 5 errata-xmlrpc 2017-02-06 01:17:42 EST

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6
  Red Hat Enterprise Linux 7

Via RHSA-2017:0252 https://rhn.redhat.com/errata/RHSA-2017-0252.html

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