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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.1636 Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers Denial of Service Vulnerability 24 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-2015-4205 Original Bulletin: http://tools.cisco.com/security/center/viewAlert.x?alertId=39455 - --------------------------BEGIN INCLUDED TEXT-------------------- Vulnerability Alert Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers Denial of Service Vulnerability Threat Type: CWE-399: Resource Management Errors IntelliShield ID: 39455 Version: 1 First Published: 2015 June 22 19:31 GMT Last Published: 2015 June 22 19:31 GMT Port: Not available CVE: CVE-2015-4205 Urgency: Unlikely Use Credibility: Confirmed Severity: Mild Damage CVSS Base: 5.7 CVSS Temporal: 4.7 Version Summary: Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers contains a vulnerability that could allow an unauthenticated, adjacent attacker to cause a denial of service condition. Updates are available. Description A vulnerability in flow control processing of Cisco IOS XR Software for Cisco ASR 9000 Series Routers could allow an unauthenticated, adjacent attacker to cause a Network Processing Unit (NPU) chip reset and potentially a reload of the affected line card. The vulnerability is due to improper processing of crafted IEEE 802.3x flow control pause frames. An attacker could exploit this vulnerability by sending a number of crafted IEEE 802.3x flow control pause frames to an affected device. An exploit could allow the attacker to cause an NPU chip reset and potentially a reload of the affected line card. Cisco has confirmed the vulnerability and released software updates. Warning Indicators At the time this alert was first published, Cisco ASR 9000 Series Aggregation Services Routers running Cisco IOS XR Software release 5.3.1 was vulnerable. Later releases of Cisco IOS XR Software may also be vulnerable. IntelliShield Analysis To exploit this vulnerability an attacker must have access to the same broadcast or collision domain as the targeted device. This access requirement decreases the likelihood of 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 CSCut19959 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 an NPU chip reset and potentially a reload of the line card on an affected device, resulting in a denial of service (DoS) condition. Technical Information The vulnerability is due to improper processing of crafted IEEE 802.3x flow control pause frames by an affected device. An attacker could exploit this vulnerability by sending a number of crafted IEEE 802.3x flow control pause frames to an affected device. An exploit could allow the attacker to cause an NPU chip reset and potentially a reload of the affected line card, 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 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 5.3 .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. 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: http://www.auscert.org.au/render.html?cid=1980 =========================================================================== 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 iQIVAwUBVYpFkn6ZAP0PgtI9AQKVPg//YlHDJC8KCZnq4ZHgzeX0DSrZcJoalVgB z8pP5BGvnxokpzZBQN9tCy4Id/eRTu/GUKbp2oyGlqC1rN98P04ZRs/sJCN0pHJD 08QSBefXF6uUt4DXvNSSwdS8LHSW124dg6pQ2k8Y2nRVW1Pty1ZYFVxBlXOF9KoI DiZyLlSLNLB4l0iPDdv/mm0rM2YT3O3JkH+EYOYeYmMqavvOwcpEWMfzlVv8/tSD YW+lGYQYZ2VuzQYBtxKurj5wlKcy4vlHuyP76S3VR/A853ZzA/PWOlSFOumkPxaV PMae75RtcsuCRN4DJFiV8ocYTk5AzmZu+4JhU3idE8i3cLbNoMnBhO7AJ3HI7SyN Dh3uryB9RyJk9VTvrcobZcRhQB0HWwlelDsMdpfrzZsYX7UoI5e7pk6nA5ItvfZm cFZ7t5Gbm/J0AdX6NFe64Kf/2lPpguAYK3IVcIDkA+h3GsqKc5r7TpQgjEV4doBy EbWVF6EqTU86TW8cUbTbxCBirRgNt9bkNLR7VsqckWd1vNPYv3IcIBmSnFZXkE/w 0aPrEmMyWV4s7ZFWkeTsYzZyY5RmDI9tLJGHVXmk00k4sG/bc4hTg4hhrqftFeqO zjwkDsV/48sTE6Qi1O5imLoWD/InmCmYtMINYiLoKzyk93n6AaT/+6HHKK7lgVjg RA/DtftcMyE= =4mv8 -----END PGP SIGNATURE-----