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AUSCERT External Security Bulletin Redistribution
ESB-2020.2125
Cisco IOS XR Software Standby Route Processor Gigabit Ethernet Management
Interface Access Control List Bypass Vulnerability
18 June 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XR Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Unauthorised Access -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3364
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xracl-zbWSWREt
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XR Software Standby Route Processor Gigabit Ethernet Management
Interface Access Control List Bypass Vulnerability
Priority: Medium
Advisory ID: cisco-sa-xracl-zbWSWREt
First Published: 2020 June 17 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds availableCisco Bug IDs: CSCvt55079
CVE-2020-3364
CWE-284
CVSS Score:
5.3 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:X/RL:X/RC:X
Summary
o A vulnerability in the access control list (ACL) functionality of the
standby route processor management interface of Cisco IOS XR Software could
allow an unauthenticated, remote attacker to reach the configured IP
addresses on the standby route processor management Gigabit Ethernet
Management interface.
The vulnerability is due to a logic error that was introduced in the Cisco
IOS XR Software, which prevents the ACL from working when applied against
the standby route processor management interface. An attacker could exploit
this vulnerability by attempting to access the device through the standby
route processor management interface.
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-xracl-zbWSWREt
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 XR Software and had
dual route processors and an ACL configured on the standby route processor
management interface.
At the time of publication, the release information in the following table
(s) was accurate. See the Details section in the bug ID(s) at the top of
this advisory for the most complete and current information.
Cisco IOS XR Software Train Affected Releases
6.7 6.7.1
7.0 7.0.2, 7.0.11, 7.0.12
7.1 7.1.1, 7.1.15
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Details
o This vulnerability applies to both IPv4 and IPv6 ACLs.
Workarounds
o There are no workarounds that address this vulnerability.
However, administrators can choose one of the following mitigation options
to help decrease any attack surface:
For features that leverage the TTYs, apply an ACL to all VTY lines. This
will mitigate this vulnerability for those applications, as shown in the
following example:
line template vty
access-class ingress MGMT_ACL_V4
!
vty-pool default 0 9 line-template vty
For features that leverage a feature-specific ACL, apply an ACL to the
feature itself. This will mitigate this vulnerability for those
applications as shown in the following examples:
NETCONF
ssh server netconf ipv4 access-list MGMT_ACL_V4
SSH
ssh server ipv4 access-list MGMT_ACL_V4
Telnet
telnet ipv4 server max-servers 3 access-list MGMT_ACL_V4
For features that are controlled through management plane protection, apply
an out-of-band management plane protection policy, as shown in the
following example:
control-plane
management-plane
out-of-band
interface MgmtEth0/RSP0/CPU0/0
allow all peer
address ipv4 192.168.1.1
!
!
interface MgmtEth0/RSP1/CPU0/0
allow all peer
address ipv4 192.168.1.1
!
!
Note: Applications that are accessible on the device that do not require a
TTY to be allocated and do not support application-specific ACLs are still
exposed.
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 and Alerts 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.
Fixed Releases
For information about fixed software releases, see the Details section in
the bug ID(s) at the top of this advisory.
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 found during the resolution of a Cisco TAC support
case.
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.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-xracl-zbWSWREt
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-JUN-17 |
+----------+---------------------------+----------+--------+--------------+
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