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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.1591 Cisco IOS XR IPv6 Packet Processing Denial of Service Vulnerability 18 June 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS XR Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2015-4191 Original Bulletin: http://tools.cisco.com/security/center/viewAlert.x?alertId=39383 - --------------------------BEGIN INCLUDED TEXT-------------------- Vulnerability Alert Cisco IOS XR IPv6 Packet Processing Denial of Service Vulnerability Threat Type: CWE-399: Resource Management Errors IntelliShield ID: 39383 Version: 1 First Published: 2015 June 17 18:01 GMT Last Published: 2015 June 17 18:01 GMT Port: Not available CVE: CVE-2015-4191 Urgency: Unlikely Use Credibility: Confirmed Severity: Mild Damage CVSS Base: 5.0 CVSS Version 2.0 CVSS Temporal: 4.1 Version Summary: Cisco IOS XR Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available. Description A vulnerability in IP version 6 (IPv6) processing in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a reload of the ipv6_io service. The vulnerability is due to improper processing of a malformed IPv6 packet by a device configured to process such packets. An attacker could exploit this vulnerability by sending a malformed IPv6 packet to be processed by a device that is configured for IPv6. An exploit could allow the attacker to cause a reload of the ipv6_io service. Cisco has confirmed the vulnerability and released software updates. Warning Indicators At the time this alert was first published, Cisco IOS XR Software Release 5.2.1 was vulnerable. Later releases of Cisco IOS XR Software may also be vulnerable. IntelliShield Analysis To exploit this vulnerability, an attacker may need to acquire additional information about the targeted device, such as whether the device is configured to process IPv6 packets. A device configured to process IPv6 packets is required for a successful exploit. Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available. Vendor Announcements Cisco has released bug ID CSCuq95565 for registered users, which contains additional details and an up-to-date list of affected product versions. Impact An unauthenticated, remote attacker could exploit this vulnerability to cause the ipv6_io service on an affected device to reload, resulting in a denial of service (DoS) condition. Technical Information The vulnerability is due to improper processing of a malformed IPv6 packet by an affected device. An attacker could exploit this vulnerability by sending a malformed IPv6 packet to be processed by a device that is configured for IPv6. An exploit could allow the attacker to cause reload of the affected service, resulting in a DoS condition. Safeguards Administrators are advised to apply the appropriate updates. Administrators are advised to allow only trusted users to have network access. Administrators can help protect affected systems from external attacks by using a solid firewall strategy. Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems. Administrators are advised to monitor affected systems. Patches/Software Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com. Alert History Initial Release Product Sets The security vulnerability applies to the following combinations of products. Primary Products: Cisco Cisco IOS XR Software 5.2 .1 Associated Products: N/A Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service. This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment. 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 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. 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