29 June 2015
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2015.1678 Cisco IOS Software UBR Devices IPv6 to IPv4 Subsystem Denial of Service Vulnerability 29 June 2015 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2015-4199 Original Bulletin: http://tools.cisco.com/security/center/viewAlert.x?alertId=39423 - --------------------------BEGIN INCLUDED TEXT-------------------- Vulnerability Alert Cisco IOS Software UBR Devices IPv6 to IPv4 Subsystem Denial of Service Vulnerability Threat Type: CWE-362: Race Conditions IntelliShield ID: 39423 Version: 1 First Published: 2015 June 22 14:53 GMT Last Published: 2015 June 22 14:53 GMT Port: Not available CVE: CVE-2015-4199 Urgency: Unlikely Use Credibility: Confirmed Severity: Mild Damage CVSS Base: 5.4 CVSS Version 2.0 CVSS Temporal: 4.5 Version Summary: Cisco Universal Broadband Routers running Cisco IOS Software contain a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available. Description A vulnerability in the IPv6 to IPv4 subsystem of Cisco IOS Software could allow an unauthenticated, remote attacker to trigger a Performance Routing Engine (PRE) crash on a targeted system, resulting in a denial of service (DoS) condition. The vulnerability is due to a race condition that may cause a NULL pointer to be freed. An attacker could exploit this vulnerability by submitting crafted content to a targeted device designed to trigger a race condition. A successful exploit could cause a PRE module on the device to crash, resulting in a DoS condition. Cisco has confirmed the vulnerability and released software updates. Warning Indicators Cisco UBR devices running Cisco IOS Software are affected. IntelliShield Analysis An attacker would need to cause hundreds of IPv6-enabled customer premises equipment (CPE) devices to drop and reestablish connectivity with the affected UBR simultaneously and repeatedly over a period of time. This requirement would make it difficult to achieve a successful exploit. Vendor Announcements Cisco has released bug ID CSCug47366 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 a PRE module on an affected device to crash, resulting in a DoS condition. Technical Information The vulnerability is due to a race condition that may result in a NULL pointer being freed on an affected device. An attacker could exploit this vulnerability by submitting crafted content to a targeted device designed to trigger a race condition. A successful exploit could cause a PRE module on the device to crash, 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 firstname.lastname@example.org. Alert History Initial Release Product Sets The security vulnerability applies to the following combinations of products. Primary Products: Cisco IOS 15.3S 15.3(3)S 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. 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