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AUSCERT External Security Bulletin Redistribution
ESB-2022.1605
Cisco IOS XE Software Border Gateway Protocol Resource
Public Key Infrastructure Denial of Service Vulnerability
14 April 2022
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2022-20694
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-rpki-dos-2EgCNeKE
Comment: CVSS (Max): 6.8 CVE-2022-20694 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
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Cisco IOS XE Software Border Gateway Protocol Resource Public Key
Infrastructure Denial of Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-iosxe-rpki-dos-2EgCNeKE
First Published: 2022 April 13 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvz55292
CVE Names: CVE-2022-20694
CWEs: CWE-617
Summary
o A vulnerability in the implementation of the Resource Public Key
Infrastructure (RPKI) feature of Cisco IOS XE Software could allow an
unauthenticated, remote attacker to cause the Border Gateway Protocol (BGP)
process to crash, resulting in a denial of service (DoS) condition.
This vulnerability is due to the incorrect handling of a specific RPKI to
Router (RTR) Protocol packet header. An attacker could exploit this
vulnerability by compromising the RPKI validator server and sending a
specifically crafted RTR packet to an affected device. Alternatively, the
attacker could use man-in-the-middle techniques to impersonate the RPKI
validator server and send a crafted RTR response packet over the
established RTR TCP connection to the affected device. A successful exploit
could allow the attacker to cause a DoS condition because the BGP process
could constantly restart and BGP routing could become unstable.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-rpki-dos-2EgCNeKE
This advisory is part of the April 2022 release of the Cisco IOS and IOS XE
Software Security Advisory Bundled Publication. For a complete list of the
advisories and links to them, see Cisco Event Response: April 2022
Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
Publication.
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco devices if
they were running a vulnerable release of IOS XE Software and had the RPKI
feature configured and in use .
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine Whether RPKI is Enabled
To determine whether RPKI is enabled, issue the show bgp rpki servers
command. If the command returns output, RPKI is enabled and the device is
vulnerable. The following example shows the output of a device with RPKI
configured with a server at the IP address 10.10.10.10 on port 10000:
Router# show bgp rpki servers
% Command accepted but obsolete, unreleased or unsupported; see documentation.
BGP SOVC neighbor is 10.10.10.10/10000 connected to port 10000
Flags 0, Refresh time is 600, Serial number is 0, Session ID is 0
InQ has 0 messages, OutQ has 0 messages, formatted msg 0
Session IO flags 0, Session flags 4000
Neighbor Statistics:
.
.
.
Router#
Note : The IP addresses displayed for configured neighbors depend on the
device configuration.
If the command returns no output, the device is not affected.
Products Confirmed Not Vulnerable
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
IOS Software
IOS XR Software
Meraki products
NX-OS Software
Workarounds
o There are no workarounds that address this vulnerability.
However, administrators can remove the RPKI configuration as a mitigation.
If RPKI servers are either not in use or removed from the configuration,
the device is considered not vulnerable. The decision to remove the RPKI
configuration needs careful consideration.
While this mitigation has been deployed and was proven successful in a test
environment, customers should determine the applicability and effectiveness
in their own environment and under their own use conditions. Customers
should be aware that any workaround or mitigation that is implemented may
negatively impact the functionality or performance of their network based
on intrinsic customer deployment scenarios and limitations. Customers
should not deploy any workarounds or mitigations before first evaluating
the applicability to their own environment and any impact to such
environment.
Fixed Software
o When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories page , to determine exposure and a complete
upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance
providers.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
following ways:
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
Source
o This vulnerability was reported to the Cisco PSIRT for resolution by the
U.S. National Security Agency (NSA).
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy . This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
Related to This Advisory
o Cisco Event Response: April 2022 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-rpki-dos-2EgCNeKE
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2022-APR-13 |
+----------+---------------------------+----------+--------+--------------+
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