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AUSCERT External Security Bulletin Redistribution
ESB-2021.2393
JSA11179 - 2021-07 Security Bulletin: Junos OS Evolved:
Authenticated denial of service in ntpd (CVE-2019-8936)
15 July 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Junos OS Evolved
Publisher: Juniper Networks
Operating System: Juniper
Impact/Access: Denial of Service -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2019-8936
Reference: ESB-2021.1346
ESB-2021.1255
ESB-2020.3427
Original Bulletin:
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA11179
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2021-07 Security Bulletin: Junos OS Evolved: Authenticated denial of service in ntpd (CVE-2019-8936)
Article ID : JSA11179
Last Updated: 14 Jul 2021
Version : 2.0
Product Affected:
This issue affects Junos OS Evolved All versions prior to 20.4, 21.1, 21.2.
Problem:
On Juniper Networks Junos OS Evolved devices where ntp is enabled a crafted
malicious authenticated mode 6 packet from a permitted network address can
trigger a NULL pointer dereference. Note for this attack to work, the sending
system must be on an address from which the target ntpd accepts mode 6 packets,
and must use a private key that is specifically listed as being used for mode 6
authorization. The ntpd daemon can crash due to the NULL pointer dereference,
causing a Denial of Service (DoS).
Continued receipt and processing of these crafted malicious packets will create
a sustained Denial of Service (DoS) condition.
This issue affects:
Juniper Networks Junos OS Evolved
o All versions prior to 20.4R2-S2-EVO;
o 21.1 versions prior to 21.1R2-EVO;
o 21.2 versions prior to 21.2R1-EVO.
The following minimal configuration example is provided:
[system ntp]
Juniper SIRT is not aware of any malicious exploitation of this vulnerability.
This issue was discovered during external security research.
This issue has been assigned CVE-2019-8936 .
Solution:
The following software releases have been updated to resolve this specific
issue: Junos OS Evolved: 20.4R2-S2-EVO, 21.1R2-EVO, 21.2R1-EVO, and all
subsequent releases.
This issue is being tracked as 1589449 .
Workaround:
Use 'restrict noquery' options in the ntpd configuration to limit addresses
that can send mode 6 queries.
Implementation:
Software releases or updates are available for download at https://
support.juniper.net/support/downloads/
Modification History:
2021-07-14: Initial Publication.
CVSS Score:
7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
High
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common
Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."
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