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Vulnerability Alert

Cisco IPS Software Fragmented Traffic Denial of Service Vulnerability

 
Threat Type:CWE-119: Buffer Errors
IntelliShield ID:30024
Version:1
First Published:2013 July 17 16:20 GMT
Last Published:2013 July 17 16:20 GMT
Port: Not available
CVE:CVE-2013-1218
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:6.4
Related Resources:
View related Security Advisory
 
 
Version Summary: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.
 
 
Description
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.
 
Warning Indicators
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.
 
IntelliShield Analysis
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.
 
Vendor Announcements
Cisco has released a security advisory for bug ID CSCue51272 at the following link: cisco-sa-20130717-ips
 
Impact
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.
 
Technical Information
Additional technical details are not available.
 
Safeguards
Administrators are advised to apply the appropriate updates.

Administrators are advised to allow only trusted users to have network access.

The Cisco Applied Intelligence team has created the following companion document to guide administrators in identifying and mitigating attempts to exploit this vulnerability prior to applying updated software: Identifying and Mitigating Exploitation of the Multiple Vulnerabilities in Cisco Intrusion Prevention System Software

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.

It is critical to prevent unauthorized direct communication to network devices. Restrict network traffic destined for the network infrastructure to protect against reconnaissance and denial-of-service (DoS) attacks. For configuration details, see Protecting Your Core: Infrastructure Protection Access Control Lists.

Network traffic should be monitored security-related network activity. NetFlow identifies security-related network activity. For NetFlow configuration details, see Introduction to Cisco IOS NetFlow - A Technical Overview.

Administrators are advised to monitor affected systems.
 
Patches/Software
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 tac@cisco.com
 
Alert History
 
Initial Release


Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
CiscoIntrusion Prevention System (IPS) 7.1 Base

Associated Products:
N/A




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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. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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