===================================================================== CERT-Renater Note d'Information No. 2021/VULN440 _____________________________________________________________________ DATE : 07/09/2021 HARDWARE PLATFORM(S): / OPERATING SYSTEM(S): Systems running Cisco Enterprise NFVIS versions prior to 4.6.1. ===================================================================== https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nfvis-g2DMVVh _____________________________________________________________________ Cisco Enterprise NFV Infrastructure Software Authentication Bypass Vulnerability Critical Advisory ID: cisco-sa-nfvis-g2DMVVh First Published: 2021 September 1 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvz16015 CVSS Score: Base 9.8 CVE-2021-34746 CWE-289 Summary A vulnerability in the TACACS+ authentication, authorization and accounting (AAA) feature of Cisco Enterprise NFV Infrastructure Software (NFVIS) could allow an unauthenticated, remote attacker to bypass authentication and log in to an affected device as an administrator. This vulnerability is due to incomplete validation of user-supplied input that is passed to an authentication script. An attacker could exploit this vulnerability by injecting parameters into an authentication request. A successful exploit could allow the attacker to bypass authentication and log in as an administrator to the affected 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nfvis-g2DMVVh Affected Products Vulnerable Products This vulnerability affects Cisco Enterprise NFVIS Release 4.5.1 if the TACACS external authentication method is configured. Determine TACACS External Authentication Configuration To determine if a TACACS external authentication feature is enabled on a device, use the show running-config tacacs-server command. The following example shows the output of the show running-config tacacs-server command on Cisco Enterprise NFVIS when TACACS external authentication is enabled: nfvis# show running-config tacacs-server tacacs-server host 192.168.1.1 key 0 shared-secret "example!23" admin-priv 15 oper-priv 1 ! nfvis# If the output of the show running-config tacacs-server command is No entries found, the TACACS external authentication feature is not enabled. Alternatively, check the configuration through the GUI. Choose Configuration > Host > Security > User and Roles. If a TACACS+ host is defined under External Authentication, the device is considered to be vulnerable. Configurations that are using RADIUS or local authentication only are not affected. Products Confirmed Not Vulnerable Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability. Workarounds There are no workarounds that address this vulnerability. Fixed Software Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license: https://www.cisco.com/c/en/us/products/end-user-license-agreement.html Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades. 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. Customers Without Service Contracts Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Fixed Releases Cisco fixed this vulnerability in Cisco Enterprise NFVIS releases 4.6.1 and later. Exploitation and Public Announcements The Cisco Product Security Incident Response Team (PSIRT) is aware that proof-of-concept exploit code is available for the vulnerability described in this advisory. The Cisco PSIRT is not aware of any malicious use of the vulnerability that is described in this advisory. Source Cisco would like to thank Cyrille Chatras of Orange Group for reporting this vulnerability. URL https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nfvis-g2DMVVh Revision History Version Description Section Status Date 1.0 Initial public release. - Final 2021-SEP-01 Legal Disclaimer 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. ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 23/25 Rue Daviel | fax : 01-53-94-20-41 + + 75013 Paris | email:cert@support.renater.fr + =========================================================