Bug 1397341 – CVE-2016-7429 ntp: Attack on interface selection

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Bug 1397341 - (CVE-2016-7429) CVE-2016-7429 ntp: Attack on interface selection

Summary:	CVE-2016-7429 ntp: Attack on interface selection

Status:	CLOSED ERRATA

Aliases:	CVE-2016-7429

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

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

URL:
Whiteboard:	impact=low,public=20161121,reported=2...
Keywords:	Security

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

Reported:	2016-11-22 05:50 EST by Adam Mariš
Modified:	2017-02-16 12:37 EST (History)
CC List:	7 users (show)

See Also:	1422944 1422973
Fixed In Version:	ntp-4.2.8p9
Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the way ntpd running on a host with multiple network interfaces handled certain server responses. A remote attacker could use this flaw which would cause ntpd to not synchronize with the source.
Story Points:	---
Clone Of:
Environment:
Last Closed:	2017-02-06 01:50:25 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 05:50:29 EST

When ntpd receives a server response on a socket that corresponds to a different interface than was used for the request, the peer structure is updated to use the interface for new requests. If ntpd is running on a host with multiple interfaces in separate networks and the operating system doesn't check source address in received packets (e.g. rp_filter on Linux is set to 0), an attacker that knows the address of the source can send a packet with spoofed source address which will cause ntpd to select wrong interface for the source and prevent it from sending new requests until the list of interfaces is refreshed, which happens on routing changes or every 5 minutes by default. If the attack is repeated often enough (once per second), ntpd will not be able to synchronize with the source.

External References:

http://support.ntp.org/bin/view/Main/NtpBug3072

Comment 1 Adam Mariš 2016-11-22 06:09:29 EST

Created ntp tracking bugs for this issue:

Affects: fedora-all [bug 1397351]

Comment 2 Huzaifa S. Sidhpurwala 2016-12-14 03:14:30 EST

Mitigation:

If you are going to configure your OS to disable source address checks, also configure your firewall configuration to control what interfaces can receive packets from what networks.

Comment 4 Keyur Pujara 2017-01-16 06:30:01 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 01:17:34 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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