Bug 1297471 (CVE-2015-7974)

Summary:	CVE-2015-7974 ntp: missing key check allows impersonation between authenticated peers (VU#357792)
Product:	[Other] Security Response	Reporter:	Martin Prpič <mprpic>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	jrusnack, mlichvar, sardella, security-response-team, slawomir
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:	A flaw was found in the way NTP verified trusted keys during symmetric key authentication. An authenticated client (A) could use this flaw to modify a packet sent between a server (B) and a client (C) using a key that is different from the one known to the client (A).	Story Points:	---
Clone Of:		Environment:
Last Closed:	2016-01-20 14:32:57 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1300277, 1317795
Bug Blocks:	1297474, 1323912

Description Martin Prpič 2016-01-11 15:33:45 UTC

The following flaw was found in NTP:

Symmetric key encryption requires a single trusted key to be specified for each server configuration. A key specified only for one server should only work to authenticate that server, other trusted keys should be refused.

However, when symmetric key authentication is verified, there is no check that the key used is the key specified for the address, any trusted key can be used as long as the keyid references another key the systems share and that key is used to compute the MAC.

An authenticated client (A) could use this flaw to modify a packet sent between a server (B) and a client (C) using a key that is different from the one known to the client (A).

Comment 2 Martin Prpič 2016-01-20 09:00:59 UTC

Upstream commit:

https://github.com/ntp-project/ntp/commit/71a962710bfe066f76da9679cf4cfdeffe34e95e

Comment 3 Martin Prpič 2016-01-20 11:49:36 UTC

External References:

http://support.ntp.org/bin/view/Main/NtpBug2936
http://www.talosintel.com/reports/TALOS-2016-0071/

Comment 4 Martin Prpič 2016-01-20 12:01:30 UTC

Created ntp tracking bugs for this issue:

Affects: fedora-all [bug 1300277]

Comment 5 Martin Prpič 2016-01-20 14:32:57 UTC

Statement:

Red Hat Product Security has rated this issue as having Low security impact. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.

Comment 6 Fedora Update System 2016-01-30 18:21:07 UTC

ntp-4.2.6p5-36.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Comment 7 Fedora Update System 2016-02-21 02:24:39 UTC

ntp-4.2.6p5-36.fc22 has been pushed to the Fedora 22 stable repository. If problems still persist, please make note of it in this bug report.

Comment 9 errata-xmlrpc 2016-11-03 19:33:15 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2583 https://rhn.redhat.com/errata/RHSA-2016-2583.html