Protect yourself against future threats.
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2020.2406 libssh vulnerability CVE-2020-1730 16 July 2020 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: BIG-IP AFM SSH Proxy Publisher: F5 Networks Operating System: Network Appliance Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2020-1730 Reference: ESB-2020.1293 ESB-2020.1290 Original Bulletin: https://support.f5.com/csp/article/K05295501 - --------------------------BEGIN INCLUDED TEXT-------------------- K05295501:libssh vulnerability CVE-2020-1730 Security Advisory Original Publication Date: 15 Jul, 2020 Security Advisory Description A flaw was found in libssh versions before 0.8.9 and before 0.9.4 in the way it handled AES-CTR (or DES ciphers if enabled) ciphers. The server or client could crash when the connection hasn't been fully initialized and the system tries to cleanup the ciphers when closing the connection. The biggest threat from this vulnerability is system availability. (CVE-2020-1730) Impact An attacker may be able to compromise the availability of the system. Security Advisory Status F5 Product Development has assigned ID 921777 (BIG-IP) to this vulnerability. To determine if your product and version have been evaluated for this vulnerability, refer to the Applies to (see versions) box. To determine if your release is known to be vulnerable, the components or features that are affected by the vulnerability, and for information about releases, point releases, or hotfixes that address the vulnerability, refer to the following table. For more information about security advisory versioning, refer to K51812227: Understanding Security Advisory versioning. +-------------------+------+----------+----------+----------+------+----------+ | | |Versions |Fixes | |CVSSv3|Vulnerable| |Product |Branch|known to |introduced|Severity |score^|component | | | |be |in | |1 |or feature| | | |vulnerable| | | | | +-------------------+------+----------+----------+----------+------+----------+ | |16.x |16.0.0 |None | | | | | +------+----------+----------+ | | | | |15.x |15.0.0 - |None | | | | | | |15.1.0 | | | | | | +------+----------+----------+ | | | | |14.x |14.1.0 - |None | | | | | | |14.1.2 | | | | | |BIG-IP AFM +------+----------+----------+Medium |5.3 |AFM SSH | | |13.x |13.1.0 - |None | | |Proxy | | | |13.1.3 | | | | | | +------+----------+----------+ | | | | |12.x |12.1.0 - |None | | | | | | |12.1.5 | | | | | | +------+----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ | |16.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | | |15.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | |BIG-IP (LTM, AAM, |14.x |None |Not | | | | |Analytics, APM, | | |applicable|Not | | | |ASM, DNS, FPS, GTM,+------+----------+----------+vulnerable|None |None | |Link Controller, |13.x |None |Not | | | | |PEM) | | |applicable| | | | | +------+----------+----------+ | | | | |12.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | | |11.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ | |7.x |None |Not | | | | | | | |applicable| | | | | +------+----------+----------+ | | | |BIG-IQ Centralized |6.x |None |Not |Not |None |None | |Management | | |applicable|vulnerable| | | | +------+----------+----------+ | | | | |5.x |None |Not | | | | | | | |applicable| | | | +-------------------+------+----------+----------+----------+------+----------+ |Traffix SDC |5.x |None |Not |Not |None |None | | | | |applicable|vulnerable| | | +-------------------+------+----------+----------+----------+------+----------+ ^1The CVSSv3 score link takes you to a resource outside of AskF5, and it is possible that the document may be removed without our knowledge. Security Advisory Recommended Actions If you are running a version listed in the Versions known to be vulnerable column, you can eliminate this vulnerability by upgrading to a version listed in the Fixes introduced in column. If the table lists only an older version than what you are currently running, or does not list a non-vulnerable version, then no upgrade candidate currently exists. Mitigation To mitigate this vulnerability, you can disable the use of AES-CTR and DES-CTR ciphers on the clients and servers. For example, to disable AES-CTR ciphers, you can remove the aes128-ctr, aes192-ctr, and aes256-ctr ciphers from the Ciphers keyword in the following SSH configuration files: o /etc/ssh/ssh_config (clients) o /etc/ssh/sshd_config (servers) If the Ciphers keyword is not already specified in the listed configuration files, you can disable the affected ciphers by adding the Ciphers keyword to the configuration files and specifying the allowed ciphers as arguments. For more information about configuring allowed ciphers for SSH clients and servers, refer to the SSH documentation for your software. Supplemental Information o K41942608: Overview of Security Advisory articles o K4602: Overview of the F5 security vulnerability response policy o K4918: Overview of the F5 critical issue hotfix policy o K9502: BIG-IP hotfix and point release matrix o K13123: Managing BIG-IP product hotfixes (11.x - 16.x) o K167: Downloading software and firmware from F5 o K9970: Subscribing to email notifications regarding F5 products o K9957: Creating a custom RSS feed to view new and updated documents - --------------------------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). On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBXw+EhuNLKJtyKPYoAQjo4xAAp5tmumJOE3uBBxTcXcPPtPw0zf1wtUXJ IYg1xGjxkZv844/JbeZXxWd8GohdcZfmmFGnQz2uDV31S4jWPeDoSQcsfBVudLAO VcBq1njVsEGaw37LOB3rE4XC1WU9P/SlBjNPWBqsyaKpSXGnAU9/fKCSvgn9lvmv bRC5jx1Plt77GRel4POjl3ewJ1gUPJpS3bS5vX3xMkvHfmK/1LiAxhKbyJm+edw7 DkxtBSy5ouPaxouxMEimyiNGpzqvBpuSdz0e4F00BVXZ5Lb9RqD59iWdNeYF0Lo7 C6y5tAIKyOnngLB+RmhkoQLyDHGKfT4TUwzSIzy5cavaGCJSafBuvf1vkVlag947 I8qdF+ECsU3HsOpR5rR/0hCD5Tjt1YlVIVKT/VSgfqiegkfBiHeo1GygPWhaobYr xvxrgA6K3f5GZke/JX/mV8iAWAyfWznXBZr9SR2QY8jyDGmxp2j6/aJ/0GBEJhhT nyqk3PKngMn9OUIwr8/px4qV66JnUpqtUR8rk67cvwGH+cMuSx5fCqCQ+XsDdALq 65U+6HsYmlpbK0I0B0+CdLhX2z0MOESnMhu3fOffHgpEbzvXm3g5u42sqRlp6rh1 Emo/vQHVF7l+td7n5JnpSLJyfdg4HcwlohZyWbHUQzLK+8BCLYGYCEeNjLxZAp72 pQnWeiKtjLk= =QjVm -----END PGP SIGNATURE-----