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)
Keywords:
Status: CLOSED NOTABUG
Alias: CVE-2016-4957
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:
Blocks: 1302226
TreeView+ depends on / blocked
 
Reported: 2016-05-30 12:16 UTC by Martin Prpič
Modified: 2021-02-17 03:48 UTC (History)
5 users (show)

Fixed In Version: ntp-4.2.8p7
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Environment:
Last Closed: 2016-05-30 12:58:58 UTC
Embargoed:

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Description Martin Prpič 2016-05-30 12:16:57 UTC 
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 12:17:01 UTC 
Acknowledgments:

Name: CERT/CC
Upstream: Nicolas Edet (Cisco)
Comment 2 Martin Prpič 2016-05-30 12:58:58 UTC 
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 13:41:34 UTC 
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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