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Vulnerability Alert

Cisco ASA Next-Generation Firewall Fragmented Traffic Denial of Service Vulnerability

 
Threat Type:CWE-20: Input Validation
IntelliShield ID:29708
Version:1
First Published:2013 June 26 16:17 GMT
Last Published:2013 June 26 16:17 GMT
Port: Not available
CVE:CVE-2013-3382
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:6.8
 
Version Summary:Cisco ASA Next-Generation Firewall contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
 
 
Description
A vulnerability in fragmented traffic processing on Cisco ASA NGFW could allow an unauthenticated, remote attacker to cause a reload of the affected device.

The vulnerability is due to invalid parsing of reassembled packet data. An attacker could exploit this vulnerability by sending fragmented traffic to be processed by one of the ASA NGFW deny policies.

Cisco has confirmed the vulnerability in a security advisory and has released software updates.
 
Warning Indicators
The following Cisco products are vulnerable:
  • Cisco ASA NGFW versions prior to 9.1.1.9
  • Cisco NGFW versions prior to 9.1.2.12
 
IntelliShield Analysis
To exploit this vulnerability, an affected Cisco ASA NGFW, also known as Cisco ASA CX Context-Aware Security in versions prior to 9.1.2, needs a configured policy that denies user traffic. In addition, an attacker may require access to trusted, internal networks to send fragmented traffic to an affected device. These requirements 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 Cisco bug ID CSCue88387 at the following link: cisco-sa-20130626-ngfw
 
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause an affected device to reload or stop processing user traffic, resulting in a denial of service (DoS) condition. In addition, if an affected device with a Cisco ASA NGFW module running an affected version of the software is configured in High-Availability (HA) mode, a failover event may occur when the Cisco ASA NGFW reloads or stops forwarding traffic. Repeated exploitation could result in a sustained failover condition of the parent Cisco ASA and lead to a sustained DoS condition.
 
Technical Information
The vulnerability is due to invalid parsing of reassembled packet data processed by the affected software.

An unauthenticated, remote attacker could exploit this vulnerability by sending fragmented traffic to be processed by one of the ASA NGFW deny policies. If successful, the attacker can cause an affected device to reload or stop processing user traffic, resulting in a DoS condition.
 
Safeguards
Administrators are advised to apply the appropriate updates.

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

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 may consider disabling the Modular Policy Framework (MPF) configuration on the Cisco ASA that is used to direct the user traffic toward the Cisco ASA NGFW. Details on disabling this configuration are in the "Workarounds" section of the security advisory.

Administrators are advised to monitor affected systems.
 
Patches/Software
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. 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:
CiscoCisco ASA CX Context-Aware Security Software 9.0 Base, .1, .1-40, .2, .2-68

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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