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
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
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 |
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
This vulnerability applies to both IPv4 and IPv6 ACLs.
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.
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.
For information about fixed software releases, see the Details section in the bug ID(s) at the top of this advisory.
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.
This vulnerability was found during the resolution of a Cisco TAC support case.
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.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.0 | Initial public release. | - | Final | 2020-JUN-17 |
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