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 implementation of the code that processes fragmented traffic could allow an unauthenticated, remote attacker to cause the Analysis Engine process to become unresponsive or cause the affected system to reload.
The vulnerability is due to improper handling of fragmented IP packets sent from the Cisco ASA data plane to the Cisco IPS processor for inspection and processing. An attacker could exploit this vulnerability by sending a combination of fragmented and other IP packets through the affected system. An exploit could allow the attacker to cause a reload of the affected system or cause the Analysis Engine process to become unresponsive. When the Analysis Engine process is unresponsive, the affected system will not process traffic, which will cause that traffic to be dropped. Additionally, if the Cisco ASA with a Cisco IPS SSP software module running an
affected version of software is configured in High-Availability mode (HA), a failover event may be triggered when the Cisco IPS SSP reloads or stops forwarding traffic.
The vulnerability can be triggered by IPv4 and IPv6 fragmented packets passing through the affected system. Traffic directed to the management IP address of the Cisco IPS software module will not trigger this vulnerability.
Cisco has confirmed the vulnerability in a security advisory and has released software updates.
Cisco IPS Software versions 7.1(4)E4 through 7.1(7)E4 are affected when running on Cisco ASA 5500-X Series (IPS SSP) software modules.
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.
An unauthenticated, remote attacker could exploit the vulnerability to cause the Analysis Engine process to become unresponsive to legitimate user requests, or cause the targeted device to reload abnormally, leading to a DoS condition.
Additional technical details are not available.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider disabling the Modular Policy Framework (MPF) configuration on the Cisco ASA that is used to direct the user traffic toward the Cisco IPS SSP. Details on disabling this configuration are in the "Workarounds" section of the security advisory.
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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