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AUSCERT External Security Bulletin Redistribution
ESB-2024.1846
Cisco IOS XE Software NETCONF/RESTCONF IPv4 Access Control List Bypass
Vulnerability
28 March 2024
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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-2024-20316
Original Bulletin:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-dmi-acl-bypass-Xv8FO8Vz
Comment: CVSS (Max): 5.8 CVE-2024-20316 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
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Cisco IOS XE Software NETCONF/RESTCONF IPv4 Access Control List Bypass
Vulnerability
Priority: Medium
Advisory ID: cisco-sa-dmi-acl-bypass-Xv8FO8Vz
First Published: 2024 March 27 16:00 GMT
Version 1.0: Final
Workarounds: Yes
Cisco Bug IDs: CSCwe12169 CSCwf92391
CVE Names: CVE-2024-20316
CWEs: CWE-390
Summary
o A vulnerability in the data model interface (DMI) services of Cisco IOS XE
Software could allow an unauthenticated, remote attacker to access
resources that should have been protected by a configured IPv4 access
control list (ACL).
This vulnerability is due to improper handling of error conditions when a
successfully authorized device administrator updates an IPv4 ACL using the
NETCONF or RESTCONF protocol, and the update would reorder access control
entries (ACEs) in the updated ACL. An attacker could exploit this
vulnerability by accessing resources that should have been protected across
an affected device.
Cisco has released software updates that address this vulnerability. There
are workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-dmi-acl-bypass-Xv8FO8Vz
This advisory is part of the March 2024 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: March 2024
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 Cisco IOS XE Software and had the
NETCONF or RESTCONF feature enabled to manage configured IPv4 ACLs.
The following ACL types are affected by this vulnerability:
IPv4 standard ACLs
IPv4 extended ACLs when they include ACEs with the log or log-input
option
IPv6 ACLs are not affected by this vulnerability.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
Both the NETCONF and RESTCONF features are disabled in Cisco IOS XE
Software by default.
Determine Whether NETCONF is Enabled
To determine whether the NETCONF feature is enabled, use the show
running-config | include netconf-yang CLI command. If the output of the
command returns netconf-yang on a line by itself, the NETCONF feature is
enabled, as shown in the following example:
router#show running-config | include netconf-yang
netconf-yang
netconf-yang feature candidate-datastore
router#
If the output of this command is empty or does not contain netconf-yang on
a line by itself, the NETCONF feature is disabled.
Determine Whether RESTCONF is Enabled
To determine whether the RESTCONF feature is enabled, use the show
running-config | include restconf CLI command. If the output of the command
returns restconf on a line by itself, the RESTCONF feature is enabled, as
shown in the following example:
router#show running-config | include restconf
restconf
router#
If the output of this command is empty or does not contain restconf on a
line by itself, the RESTCONF feature is disabled.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
IOS Software
IOS XR Software
Meraki products
NX-OS Software
Indicators of Compromise
o If the following messages are seen in the device logs, the device could be
in a vulnerable state:
%DMI-5-SYNC_NEEDED: R0/0: dmiauthd: Configuration change requiring running configuration sync detected - 'Failed to rollback configuration'. The running configuration will be synchronized to the NETCONF running data store.
%DMI-5-SYNC_START: R0/0: dmiauthd: Synchronization of the running configuration to the NETCONF running data store has started.
%DMI-3-SYNC_ERR: R0/0: dmiauthd: An attempt to synchronize the running configuration to the NETCONF running data store has failed:
%DMI-3-DMI_DEGRADED: R0/0: dmiauthd: The dmi infra is operating in degraded mode. Most synchronizations from IOS to NETCONF datastore will not be performed
If these logs are seen on a device, manually compare the current
running-config to the expected configuration of the device, especially with
regard to configured ACLs.
Workarounds
o There is a workaround that addresses this vulnerability.
Manage ACLs directly on the device CLI instead of using the NETCONF or
RESTCONF protocol.
While this workaround 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 . This tool
identifies any Cisco security advisories that impact a specific software
release and the earliest release that fixes the vulnerabilities that are
described in each advisory ("First Fixed"). If applicable, the tool also
returns the earliest release that fixes all the vulnerabilities that are
described in all the advisories that the Software Checker identifies
("Combined First Fixed").
To use the tool, go to the Cisco Software Checker page and follow the
instructions. Alternatively, use the following form to determine whether a
release is affected by any Cisco Security Advisory. To use the form, follow
these steps:
1. Choose which advisories the tool will search-only this advisory, only
advisories with a Critical or High Security Impact Rating (SIR) , or
all advisories.
2. Enter a release number-for example, 15.9(3)M2 or 17.3.3.
3. Click Check .
[2 ] [ ] [Critical,High,Medium]
[Only this advisory ]
[ ] [Check]
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 Cisco would like to thank Andrej Mikus of Tronet for reporting this
vulnerability.
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.
Subscribe to Cisco Security Notifications
o Subscribe
Related to This Advisory
o Cisco Event Response: March 2024 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
URL
o https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-dmi-acl-bypass-Xv8FO8Vz
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2024-MAR-27 |
+----------+---------------------------+----------+--------+--------------+
Legal Disclaimer
o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT
OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information
or contain factual errors. The information in this document is intended for
end users of Cisco products.
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