Cisco Security Advisory
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CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:N/E:X/RL:X/RC:X
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A vulnerability in the web UI of Cisco IOS XE Software could allow an authenticated, remote attacker to execute arbitrary code with root privileges on the underlying operating system of an affected device.
The vulnerability exists because the affected software improperly sanitizes values that are parsed from a specific configuration file. An attacker could exploit this vulnerability by tampering with a specific configuration file and then sending an API call. A successful exploit could allow the attacker to inject arbitrary code that would be executed on the underlying operating system of the affected device. To exploit this vulnerability, the attacker would need to have a privileged set of credentials to the device.
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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-os-cmd-inj-Ef6TV5e9
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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 HTTP Server feature enabled. The default state of the HTTP Server feature in Cisco IOS XE Software is version and platform dependent.
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine the HTTP Server Configuration
To determine whether the HTTP Server feature is enabled for a device, log in to the device and use the show running-config | include ip http server|secure|active command in the CLI to check for the presence of the ip http server command or the ip http secure-server command in the global configuration. If either command is present and configured, the HTTP Server feature is enabled for the device.
The following example shows the output of the show running-config | include ip http server|secure|active command for a device that has the HTTP Server feature enabled:
Router# show running-config | include ip http server|secure|active
ip http server
ip http secure-serverNote: The presence of either command or both commands in the device configuration indicates that the web UI feature is enabled.
If the ip http server command is present and the configuration also contains ip http active-session-modules none, the vulnerability is not exploitable over HTTP.
If the ip http secure-server command is present and the configuration also contains ip http secure-active-session-modules none, the vulnerability is not exploitable over HTTPS.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
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There are no workarounds that address this vulnerability.
Disabling the HTTP Server feature eliminates the attack vector for this vulnerability and may be a suitable mitigation until affected devices can be upgraded. To disable the HTTP Server feature, use the no ip http server or no ip http secure-server command in global configuration mode. If both the HTTP server and HTTPS server are in use, both commands are required to disable the HTTP Server feature.
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.
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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.
Customers can also use the following form to determine whether a release is affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE Software release—for example, 15.1(4)M2 or 3.13.8S:
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.
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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.
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This vulnerability was found by X.B. of Cisco during internal security testing.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2021-MAR-24
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