===================================================================                               CERT-Renater

                     Note d'Information No. 2023/VULN287

_____________________________________________________________________

DATE                : 01/09/2023

HARDWARE PLATFORM(S): Juniper.

OPERATING SYSTEM(S): Junos OS versions prior to 23.4R1,
                      Junos OS versions prior to 23.4R1-EVO.

====================================================================https://supportportal.juniper.net/s/article/2023-08-29-Out-of-Cycle-Security-Bulletin-Junos-OS-and-Junos-OS-Evolved-A-crafted-BGP-UPDATE-message-allows-a-remote-attacker-to-de-peer-reset-BGP-sessions-CVE-2023-4481?language=en_US
_____________________________________________________________________

2023-08-29 Out-of-Cycle Security Bulletin: Junos OS and Junos OS
Evolved: A crafted BGP UPDATE message allows a remote attacker to
de-peer (reset) BGP sessions (CVE-2023-4481)

Article ID
JSA72510

Created
2023-08-29

Last Updated
2023-08-29

Product Affected
This issue affects all versions of Junos OS prior to 23.4R1. This
issue affects all versions of Junos OS Evolved prior to 23.4R1-EVO.

Severity
High

Severity Assessment (CVSS) Score
7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem
An Improper Input Validation vulnerability in the Routing Protocol Daemon
(rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an
unauthenticated, network-based attacker to cause a Denial of Service
(DoS).

When certain specific crafted BGP UPDATE messages are received over
an established BGP session, one BGP session may be torn down with
an UPDATE message error, or the issue may propagate beyond the local
system which will remain non-impacted, but may affect one or more
remote systems. This issue is exploitable remotely as the crafted
UPDATE message can propagate through unaffected systems and
intermediate BGP speakers.


Continuous receipt of the crafted BGP UPDATE messages will create
a sustained Denial of Service (DoS) condition for impacted devices.

This issue affects eBGP and iBGP, in both IPv4 and IPv6 implementations.
This issue requires a remote attacker to have at least one established
BGP session.


Solution

The following software releases have been updated to resolve this
specific issue:

Junos OS: 23.4R1*, and all subsequent releases.

Junos OS Evolved: 23.4R1-EVO*, and all subsequent releases.

*Pending Publication – Please note: Additional releases before 23.4R1
for Junos OS and 23.4R1-EVO for Junos OS Evolved are being worked on
at this time. Please monitor PRSearch ongoing, and subscribe to this
advisory, to see  additional resolved in releases as they become
available or as this advisory is updated.

It is important that customers implement the workaround in addition
to taking any updated software as these crafted UPDATE messages may
be propagated to other devices even if non-impacted locally, thereby
protecting the network by stopping the propagation of these crafted
UPDATE messages.


The workaround is to configure BGP error tolerance by way of:

   [ protocols bgp bgp-error-tolerance ... ]

Additional details can be found at
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h...

Juniper considers configuring this option to be a Best Common
Practice (BCP) as it not only prevents this issue from happening,
but protects against similar issues as well.

This issue is being tracked as PR 1709837 which is visible on
the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are
beyond End of Engineering (EOE) or End of Life (EOL).


Workaround

The workaround is to configure BGP error tolerance by way of:

   [ protocols bgp bgp-error-tolerance ... ]

Additional details can be found at
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.h...

Juniper considers configuring this option to be a Best Common
Practice (BCP) as it not only prevents this issue from happening,
but protects against similar issues as well.


Modification History

2023-08-29: Initial Publication


Related Information

     KB16613: Overview of the Juniper Networks SIRT Quarterly
Security Bulletin Publication Process
     KB16765: In which releases are vulnerabilities fixed?
     KB16446: Common Vulnerability Scoring System (CVSS) and
Juniper's Security Advisories
     Report a Security Vulnerability - How to Contact the Juniper
Networks Security Incident Response Team
     CVE-2023-4481 at cve.mitre.org
     https://kb.juniper.net/JSA72510
 
https://www.juniper.net/documentation/us/en/software/junos/bgp/topics/topic-map/bgp-error-messages.html


Acknowledgements

The Juniper SIRT would like to acknowledge and thank Ben Cartwright-Cox
/ bgp.tools, Finder, for responsibly reporting this vulnerability.

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