22 September 2015
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.2464 Cisco Nexus 9000 Series Switches Reserved VLAN Number Vulnerability 22 September 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco Nexus 9000 Series Switches Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Mitigation CVE Names: CVE-2015-6295 Original Bulletin: http://tools.cisco.com/security/center/viewAlert.x?alertId=40990 - --------------------------BEGIN INCLUDED TEXT-------------------- Vulnerability Alert Cisco Nexus 9000 Series Switches Reserved VLAN Number Vulnerability Threat Type: CWE-399: Resource Management Errors IntelliShield ID: 40990 Version: 1 First Published: 2015 September 16 16:08 GMT Last Published: 2015 September 16 16:08 GMT Port: Not available CVE: CVE-2015-6295 Urgency: Unlikely Use Credibility: Confirmed Severity: Mild Damage CVSS Base: 4.8 CVSS Temporal: 4.6 Version Summary: Cisco Nexus 9000 Series Switches contain a vulnerability that could allow an unauthenticated, adjacent attacker to cause a denial of service condition. Updates are not available. Description A vulnerability in the handling of incoming Layer 2 packets tagged with a Cisco Nexus 9000 Series Switch (N9K) reserved VLAN number could allow an unauthenticated, adjacent attacker to cause a partial denial of service (DoS) condition due to increased CPU utilization and possible control plane instability. In addition, Layer 2 packets, which should be dropped by the switch, may be incorrectly forwarded to the connected interfaces. The vulnerability is due to lack of validation of the VLAN number in the Layer 2 packet. An attacker could exploit this vulnerability by sending a crafted Layer 2 packet tagged with an N9K reserved VLAN number. An exploit could allow the attacker to cause a partial DoS condition due to increased CPU utilization and possible control plane instability. In addition, this packet should be dropped by the N9K, but could be forwarded to the attached networks. Cisco has confirmed the vulnerability; however, updates are not available. Warning Indicators At the time this alert was first published, Cisco Nexus 9000 Series Software Releases 6.1(2)I3(4) and 7.0(3)I1(1) were vulnerable. Later releases may also be affected. IntelliShield Analysis To exploit the vulnerability, an unauthenticated attacker would need access to the local network. This restriction reduces the potential for exploitation. Vendor Announcements Cisco has released bug ID CSCuw13560 for registered users, which contains additional details and an up-to-date list of affected product versions. Impact An unauthenticated, adjacent attacker could exploit this vulnerability to cause a DoS condition. A successful exploit may also impact confidentiality due to errors in handling network packets. Technical Information The vulnerability is due to lack of validation of the VLAN number in the Layer 2 packet. An unauthenticated, adjacent attacker could exploit this vulnerability by sending a crafted Layer 2 packet tagged with an N9K reserved VLAN number. An exploit could allow the attacker to cause a DoS condition due to increased CPU and control plane instability. If the Layer 2 packet is not dropped by the N9K, it could also be forwarded to the attached networks. Safeguards Administrators are advised to contact the vendor regarding future updates and releases. Administrators are advised to monitor affected systems. Administrators are advised to change the reserved VLAN range so that it does not conflict with incoming traffic. Patches/Software Updates are not available. Alert History Initial Release Product Sets The security vulnerability applies to the following combinations of products. Primary Products: Cisco Cisco NX-OS Software for Nexus 9000 Series 7.0(3)I1(1), 6.1(2)I3(4) Associated Products: N/A LEGAL DISCLAIMER The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME. - --------------------------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 firstname.lastname@example.org 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. 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On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQIVAwUBVgDgXn6ZAP0PgtI9AQI6WhAAuflhUfTFJ4w2pUdlx1eGJSwW/QWu/RTj q5t4wS310CfvjIZd1hlOiG8tv2/YIY9h4JNOjBbNp+6y2zEESYNBkSn6EJPYqQhU XdfiVAnuXo3PLKRYRazQhHkcm8WCNdAt4w46P9gGDQwpIFFANKWyUCzYYB9xRtaD 5pWYiSQg6MoRTes1YB56iZbZqDVhW3O1I1CirjypEdC/DqWCNkya2zJbN4ZW9URB EH9VcSuf/9HM03I8B3xsk+9/d3NnBZZ6dOD6Uw0uV+O5Qjw5ObUdV+tj/h1NhXph EQK3eTSoEBVftP2g5zL4MspTgJm96o5+dqfzNrUGYpSMK2cDYTcdpbmPxkWwoDv+ gf7YMKtwbD03eqEKA+5MOHBy6JD5UQ5JXwS36lFdoJ/w2OsALsQWL3YVbyCaOkt/ XzdDjWj1lwlFqPm1ALO0JA9FecgMcoMrhSctpyEXnoCLNwmBWNA/cnWcTruAPflJ 7DcZ6K+L9sTjJniSWFvryg7gfTVxehTeeCK7+ra4Krxf2wWentAojfu5R2JNLU65 SLpW80JJRTw2Wh+++XwMjlGwCq8om8fod03e4CWNbGi0xs0fmNdJMDXN/ll+aSnY I1egS0+EuwFwoN2yzeipqREczXvIWKd4N4mES1O6cH3sG68mKRiWe5PmtbU/fHe+ oLYGyaAaZss= =WVYr -----END PGP SIGNATURE-----