Cisco Security Advisory
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AV:N/AC:L/Au:N/C:N/I:N/A:P/E:F/RL:OF/RC:C
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A vulnerability in the DHCP process of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper processing of crafted DHCP messages on a targeted interface of an affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending large amounts of crafted DHCP messages to a targeted interface on an affected device. A successful exploit could cause the device to stop responding to DHCP requests on that interface, resulting in a DoS condition.
Cisco has confirmed the vulnerability and released software updates.
To exploit this vulnerability, an attacker may need access to trusted, internal networks behind a firewall to send large amounts of crafted DHCP messages to an interface on the device. This access requirement may reduce 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.
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Cisco has released bug ID CSCup67822 for registered users that contains additional details and an up-to-date list of affected product versions.
Vulnerable Products
At the time this alert was first published, Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers version 5.2.2 was vulnerable. Later versions of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers may also be vulnerable.Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by these vulnerabilities.
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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 can help protect affected systems from external attacks by using a solid firewall strategy.
Administrators are advised to monitor affected systems.
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Cisco customers with active contracts should contact their Cisco support team for assistance in upgrading to a software version that includes fixes for this vulnerability. Cisco customers without contracts may contact the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com for assistance.
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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.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial Release NA Final 2015-Mar-24
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