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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.2632 ConfD CLI Secure Shell Server Privilege Escalation Vulnerability 5 August 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco ConfD Publisher: Cisco Systems Operating System: Cisco Impact/Access: Execute Arbitrary Code/Commands -- Existing Account Increased Privileges -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2021-1572 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-confd-priv-esc-LsGtCRx4 - --------------------------BEGIN INCLUDED TEXT-------------------- ConfD CLI Secure Shell Server Privilege Escalation Vulnerability Priority: High Advisory ID: cisco-sa-confd-priv-esc-LsGtCRx4 First Published: 2021 August 4 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvy43896 CVE Names: CVE-2021-1572 CWEs: CWE-266 Summary o A vulnerability in ConfD could allow an authenticated, local attacker to execute arbitrary commands at the level of the account under which ConfD is running, which is commonly root . To exploit this vulnerability, an attacker must have a valid account on an affected device. The vulnerability exists because the affected software incorrectly runs the SFTP user service at the privilege level of the account that was running when the ConfD built-in Secure Shell (SSH) server for CLI was enabled. If the ConfD built-in SSH server was not enabled, the device is not affected by this vulnerability. An attacker with low-level privileges could exploit this vulnerability by authenticating to an affected device and issuing a series of commands at the SFTP interface. A successful exploit could allow the attacker to elevate privileges to the level of the account under which ConfD is running, which is commonly root . Note: Any user who can authenticate to the built-in SSH server may exploit this vulnerability. By default, all ConfD users have this access if the server is enabled. Software updates that address this vulnerability have been released. 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-confd-priv-esc-LsGtCRx4 Affected Products o Vulnerable Products This vulnerability affects the following releases of ConfD if the built-in SSH server for CLI is enabled: Releases 7.4 through 7.4.3 Releases 7.5 through 7.5.2 To determine whether the built-in SSH server is enabled, see Section 4.1.1, "Disable built-in support for SSH in ConfD," in the ConfD and High Security Applications V2 application note. Products Confirmed Not Vulnerable Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability. Workarounds o There are no workarounds that address this vulnerability. However, a mitigation is available. Administrators can disable the ConfD built-in SSH server and use an external SSH server such as OpenSSH. For guidance on disabling the built-in support of SSH in ConfD, see Section 4.1.1, "Disable built-in support for SSH in ConfD," in the ConfD and High Security Applications V2 application note. 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. Fixed Software o Tail-f, a Cisco company, has released 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 a current license and have a valid support and maintenance agreement. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of their license agreement with Tail-f Systems AB. Security software updates do not entitle customers to a new software license or additional software feature sets. 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. Customers who have a current license and have a valid support and maintenance agreement can download the fixed version of software from their existing Tail-f delivery server download account. 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 open a support ticket in the Tail-f Support system. Fixed Releases This vulnerability is fixed in ConfD releases 7.4.3.1 and later and releases 7.5.2.1 and later. 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-confd-priv-esc-LsGtCRx4 Revision History o +----------+---------------------------+----------+--------+--------------+ | Version | Description | Section | Status | Date | +----------+---------------------------+----------+--------+--------------+ | 1.0 | Initial public release. | - | Final | 2021-AUG-04 | +----------+---------------------------+----------+--------+--------------+ - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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