Cisco IPS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted device. Updates are available.
A vulnerability in the IP stack could allow an unauthenticated, remote attacker to cause the MainApp process to become unresponsive. This creates a denial of service (DoS) condition because the Cisco IPS sensor is not able to execute several critical tasks including alert notification, event store management, and sensor authentication. The Cisco IPS web server will also be unavailable while the MainApp process is unresponsive. Additionally, due to this general system failure, other processes such as the Analysis Engine may not work properly. The vulnerability is due to improper handling of malformed IP packets from the management interface of the affected system. An attacker may exploit this vulnerability by sending malformed IP packets to the management interface.
The vulnerability can be triggered only by IPv4 traffic directed to the management interface. Traffic passing through the sensing interfaces will not trigger this vulnerability. If the Cisco IPS is configured in promiscuous mode, mitigation actions that require MainApp processing such as shun or rate-limit may be unavailable. If the Cisco IPS is configured in inline mode, the sensor may not correctly perform inspection and mitigation actions because the Analysis Engine process may not be working properly.
Cisco has confirmed the vulnerability in a security advisory and has released software updates.
The following Cisco products are affected:
Cisco IPS Software versions 7.1 to 7.1(4)E4 when running on Cisco ASA 5500-X Series IPS Security Services Processor (IPS SSP)
Cisco IPS Software version 7.1(4)E4 when running on Cisco IPS 4500 Series Sensors
Cisco IPS Software versions 7.1(3)E4 and 7.1(4)E4 when running on Cisco IPS 4300 Series Sensors
To exploit this vulnerability, an attacker may require access to trusted, internal networks to send crafted requests to the affected software. This access requirement could limit 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.
Prevent disruption of communication between devices by reducing the impact of attacks which may directly impact the CPU performance of the individual devices. For control plane hardening best practices, see Cisco Guide to Harden Cisco IOS Devices.
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.
Administrators are advised to monitor affected systems.
Cisco customers with active contracts can obtain updates through the Software Center. 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.
The security vulnerability applies to the following combinations of products.
Intrusion Prevention System (IPS)
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