Cisco Security Advisory
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AV:N/AC:M/Au:N/C:N/I:N/A:P/E:F/RL:OF/RC:C
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Cisco Adaptive Security Appliance (ASA) Software contains a vulnerability that could allow an unauthenticated, remote attacker to fill the connection table in the ASA preventing new connections to be established through the device.
The vulnerability is due to the ASA not honoring the idle timeout for some protocol inspected connections. An attacker could exploit this vulnerability by sending several crafted requests for one or more protocols configured for inspection on the ASA. A successful exploit could allow the attacker to force the ASA to stop accepting new connections, resulting in a denial of service (DoS) condition.
Cisco has confirmed the vulnerability in a security notice and released software updates.
To exploit this vulnerability, an attacker may require access to trusted, internal networks to send crafted requests to an affected device. This access requirement could limit the likelihood of a successful exploit.
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Customers are advised to consult Cisco bug IDs CSCuh13899 for the most complete list of affected product versions.
Vulnerable Products
At the time this alert was first published, Cisco ASA Software versions 9.1.2 and prior were vulnerable. Later releases of Cisco ASA Software 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.
Understanding activity on the network provides information and visibility that can be used to identify potential security incidents. Organizations should log events from devices and review the logged data to provide insight into anomalies or malicious activity. For logging best practices, see Cisco Guide to Harden Cisco IOS Devices.
It is critical to prevent unauthorized direct communication to network devices. Restrict network traffic destined for the network infrastructure to protect against reconnaissance and DoS attacks. For configuration details, see Protecting Your Core: Infrastructure Protection Access Control Lists.
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 2013-Aug-30
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