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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.1334 Cisco ASR 9000 Series Aggregation Services Routers ACL Bypass Vulnerability 18 April 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco ASR 9000 Series Publisher: Cisco Systems Operating System: Cisco Impact/Access: Reduced Security -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2019-1686 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190417-iosxracl - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco ASR 9000 Series Aggregation Services Routers ACL Bypass Vulnerability Priority: Medium Advisory ID: cisco-sa-20190417-iosxracl First Published: 2019 April 17 16:00 GMT Version 1.0: Final Workarounds: Yes Cisco Bug IDs: CSCvm01102 CVE-2019-1686 CWE-284 CVSS Score: 5.8 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X Summary o A vulnerability in the TCP flags inspection feature for access control lists (ACLs) on Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to bypass protection offered by a configured ACL on an affected device. The vulnerability is due to incorrect processing of the ACL applied to an interface of an affected device when Cisco Express Forwarding load balancing using the 3-tuple hash algorithm is enabled. An attacker could exploit this vulnerability by sending traffic through an affected device that should otherwise be denied by the configured ACL. An exploit could allow the attacker to bypass protection offered by a configured ACL on the affected device. There are workarounds that address this vulnerability. This advisory is available at the following link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20190417-iosxracl Affected Products o Vulnerable Products This vulnerability affects Cisco ASR 9000 Series Aggregation Services Routers only when Cisco Express Forwarding load balancing using the 3-tuple hash algorithm is enabled. This capability is not enabled by default. For information about affected configurations and software releases, consult the Cisco bug ID(s) at the top of this advisory. 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 If the 5-tuple hash algorithm is used for load balancing, the device is not affected by the vulnerability described in this advisory. If the 3-tuple hash algorithm is required, enabling ACL compression for the ACL on the interface is a workaround for this vulnerability. Fixed Software o For information about fixed software releases , consult the Cisco bug ID(s) at the top of this advisory. 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. 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-20190417-iosxracl Revision History o +---------+--------------------------+---------+--------+----------------+ | Version | Description | Section | Status | Date | +---------+--------------------------+---------+--------+----------------+ | 1.0 | Initial public release. | - | Final | 2019-April-17 | +---------+--------------------------+---------+--------+----------------+ - --------------------------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 iQIVAwUBXLe7VmaOgq3Tt24GAQh8PRAA0Lr9n06c1w/BJW7m7grqe2OgvonDK6/i Faqy6mtPagxQzQDQhn1f2o2E02qrNJV8XvMcvcMuw167IM/YgwhGudPN6Bx2YVvw 8g3OtkaTzJX9/CGt4PMKRQmbqxLjaYVAQkhPLswfTNjZ45Vox95/SQqDd0Iol2rS RTdWKI3AjpcGWXarm8zkPITLoRFy5Zxr8lUimBK+3rMBLsjWaTiLTOVXQnmhMmLy do3Kuu7j+S+lHQ9Sij9n9ZTfoOWsp+GPGPebjcxdD2jK2A18+2/iXb8xVZDlyZ0H 9MIHvzsV4LzEmU5bbTmoZV7Edp4dS7ForaUS/traHZsVbOUtno55NTxtr5bCYRgw xwwJRbV+pSD2zZsau/zFRwTOU7PYeRsWCwv3/Br8uULMRLITTifyjjp38AsNEBbL 8kA92o4IR2etU7YYzJ6L2TCtqV3EQSbbFODqIA5K1xnxqwU6Y2VAXJlDXcYDEzQm kuEn2j0iYethS1AmEjqS11kQtanJ2MPaBctENOaziAsOSLs3rG3cRjtpNCtNrl2r kr8dxPNAqa1oY49qCRWmtw1R35DMMIS3iH88BfxeUXF6xDU4WdZj0eALh6aoUCcu a1MHIbpV/lpI2WHJj/SK7vxSwnhaAYzvyPjIVWbpExEzE186Bdj1Y485iNDMGn+D kN7hrneAwDg= =KPrf -----END PGP SIGNATURE-----