Bug 1340850 – CVE-2016-4957 ntp: crypto-NAK DoS (incorrect fix for CVE-2016-1547)

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Bug 1340850 - (CVE-2016-4957) CVE-2016-4957 ntp: crypto-NAK DoS (incorrect fix for CVE-2016-1547)

Summary:	CVE-2016-4957 ntp: crypto-NAK DoS (incorrect fix for CVE-2016-1547)

Status:	CLOSED NOTABUG

Aliases:	CVE-2016-4957

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:
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URL:
Whiteboard:	impact=moderate,public=20160602,repor...
Keywords:	Security

Depends On:
Blocks:	1302226
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Reported:	2016-05-30 08:16 EDT by Martin Prpič
Modified:	2016-07-06 06:54 EDT (History)
CC List:	5 users (show)

See Also:
Fixed In Version:	ntp-4.2.8p7
Doc Type:	If docs needed, set a value
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Last Closed:	2016-05-30 08:58:58 EDT
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RHEL 7.3 requirements from Atomic Host:
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Description Martin Prpič 2016-05-30 08:16:57 EDT

It was found that the fix for CVE-2016-1547 introduced a new issue. An attacker could send a crafted packet with crypto-NAK to a server or client that will cause ntpd to crash (segfault on NULL pointer dereference).

The issue was introduced in the original patch for CVE-2016-1547 here:

http://bk1.ntp.org/ntp-stable/?PAGE=patch&REV=56b42514rgZyUCPCWq2Uyhw4BWUpSg

Comment 1 Martin Prpič 2016-05-30 08:17:01 EDT

Acknowledgments:

Name: CERT/CC
Upstream: Nicolas Edet (Cisco)

Comment 2 Martin Prpič 2016-05-30 08:58:58 EDT

Statement:

This issue did not affect the versions of ntp as shipped with any Red Hat Enterprise Linux version as they did not include the same upstream fix for CVE-2016-1547 that introduced the issue. The fix developed by Red Hat for CVE-2016-1547 did not include this issue.

Comment 3 Martin Prpič 2016-06-02 09:41:34 EDT

Upstream bug:

http://support.ntp.org/bin/view/Main/NtpBug3046

External References:

http://support.ntp.org/bin/view/Main/SecurityNotice#June_2016_ntp_4_2_8p8_NTP_Securi

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