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Cisco Security Advisory

Cisco ASA 1000V Cloud Firewall H.323 Inspection Denial of Service Vulnerability

Advisory ID: cisco-sa-20130116-asa1000v

Revision 1.0

For Public Release 2013 January 16 16:00  UTC (GMT)

Related Resources:

View related IPS SignatureView related Alert


A vulnerability in Cisco Adaptive Security Appliance (ASA) Software for the Cisco ASA 1000V Cloud Firewall may cause the Cisco ASA 1000V to reload after processing a malformed H.323 message. Cisco ASA 1000V Cloud Firewall is affected when H.323 inspection is enabled.

Cisco has released software updates that address this vulnerability.

This advisory is posted at the following link:

Note:  Only Cisco ASA Software for the Cisco ASA 1000V Cloud Firewall is affected by the vulnerability described in this advisory. Cisco ASA 5500 Series Adaptive Security Appliances, Cisco Catalyst 6500 Series ASA Services Module or Cisco Catalyst 6500 Series Firewall Services Module (FWSM) are not affected by this vulnerability.

Affected Products

Vulnerable Products

Versions 8.7.1 and of Cisco ASA Software for the Cisco ASA 1000V Cloud Firewall are affected by this vulnerability if H.323 inspection is enabled. H.323 Inspection for both H.225 and Registration, Admission and Status (RAS) messages is enabled by default.

The vulnerability exists only if H.323 inspection for H.225 messages is enabled. H.323 inspection for RAS messages has no effect on this vulnerability.

To determine whether H.323 H.225 inspection is enabled, issue the show service-policy inspect h323 h225 command and verify that a class map is configured with the H.225 inspection engine. If H.323 inspection for H.225 messages is configured, the relevant H.323 output will appear under the referenced class map.

Example output follows:
ASA1000v# show service-policy inspect h323 h225 
Global policy: 
  Service-policy: global_policy
    Class-map: inspection_default
      Inspect: h323 h225 _default_h323_map, packet 0, lock fail 0, drop 0, reset-drop 0
               tcp-proxy: bytes in buffer 0, bytes dropped 0
        h245-tunnel-block drops 0 connection

Note: The preceding output identifies a policy map with a class map that has H.323 inspection for H.225 messages applied.

Alternatively, a device that has H.323 inspection for H.225 messages enabled has a configuration similar to the following:

class-map inspection_default 
 match default-inspection-traffic
policy-map global_policy
 class inspection_default
  inspect h323 h225
service-policy global_policy global

Note: Global application is shown in the preceding example, but the service policy could also be applied to a specific interface

Customers who use Cisco Adaptive Security Device Manager (ASDM) to manage devices can check the Service Policy section under the global or interface specific policies to determine whether the inspection is enabled.

Customers who use Cisco Virtual Network Management Center (VNMC) to manage multiple devices can locate the Packet Inspection section under Policy Management > Security Policies > Root > Tenant > Data Center > Policies to determine whether the inspection is enabled.

To determine the version of Cisco ASA Software for the Cisco ASA 1000V Cloud Firewall that is running, issue the show version command from the Cisco ASA 1000V command line.

The following example shows a system that is running an affected software version (8.7.1):

ASA1000v(config)# show version
Cisco Adaptive Security Appliance Software Version 8.7(1)
Device Manager Version 6.3(5)

Customers who use the Cisco Adaptive Security Device Manager (ASDM) to manage their devices can find the version of the software displayed in the table in the login window or in the upper left corner of the ASDM window. 

Alternatively, version information can be obtained from the Summary tab of the Cisco ASA 1000V Cloud Firewall resource in the VMware vCenter Server.

Products Confirmed Not Vulnerable

With the exception of Cisco ASA 1000V Cloud Firewall, no other Cisco products are currently known to be affected by this vulnerability.


The Cisco ASA 1000V Cloud Firewall is a virtual security appliance that secures the tenant edge in multitenant private and public cloud deployments. It runs on VMware vSphere Hypervisor software and the Cisco Nexus 1000V Series Switch exclusively.

The Cisco ASA 1000V Cloud Firewall allows virtual machines (VMs) in a virtual data center to access the Internet securely, functions as the default gateway for the VMs, and protects against network-based attacks.

Cisco ASA Software for the 1000V Cloud Firewall versions 8.7.1 and contain a vulnerability that could allow an unauthenticated, remote attacker to cause a reload of the Cisco 1000V Cloud Firewall.

The vulnerability is due to incorrect handling of malformed H.323 packets. An attacker could exploit this vulnerability by sending a crafted H.323 packet through the affected device. An exploit could allow the attacker to reload the Cisco ASA 1000V Cloud Firewall, resulting in denial of service (DoS) condition.

A Cisco ASA 1000V device that is configured to inspect H.323 through-the-box traffic may reload when a malformed H.323 IPv4 packet is received. 

The H.323 control channel handles H.225, H.245 and H.323 RAS messages. H.323 inspection uses the following well-known ports:

1718—Gatekeeper Discovery UDP port
1719—RAS UDP port
1720—TCP control port

Additional dynamic UDP and TCP ports may be negotiated during the H.323 call signaling setup procedure.

A malformed packet sent to any of the well-known ports used by H.323 inspection, or to ports dynamically negotiated by H.323 call signaling setup, may trigger this vulnerability.

Only through-the-box traffic may trigger this vulnerability. Cisco ASA 1000V Cloud Firewall is affected only if H.323 inspection for H.225 messages is enabled.

Cisco ASA 1000V Cloud Firewall does not support H.323 inspection over IPv6 transport.

This vulnerability is documented in Cisco Bug ID CSCuc42812 (registered customers only) and CSCuc88741 (registered customers only) and has been assigned CVE-2012-5419.

Vulnerability Scoring Details

Cisco has scored the vulnerability in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this security advisory is in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps organizations determine the urgency and priority of a response.

Cisco has provided a base and temporal score. Customers can also compute environmental scores that help determine the impact of the vulnerability in their own networks.

Cisco has provided additional information regarding CVSS at the following link:

Cisco has also provided a CVSS calculator to compute the environmental impact for individual networks at the following link:

CSCuc42812 and CSCuc88741

Calculate the environmental score of CSCuc42812 and CSCuc88741

CVSS Base Score - 7.8

Access Vector

Access Complexity


Confidentiality Impact

Integrity Impact

Availability Impact







CVSS Temporal Score - 6.4


Remediation Level

Report Confidence





Successful exploitation of this vulnerability may cause a reload of the affected device. Repeated exploitation could result in a sustained DoS condition.

Software Versions and Fixes

When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses archive at and review subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers. 

This vulnerability has been fixed in Cisco ASA Software for the Cisco ASA 1000V Cloud Firewall version and later.

Cisco ASA Software for the Cisco ASA 1000V Cloud Firewall can be downloaded at the following link:


If H.323 inspection is not required, it can be disabled so the device is no longer affected by the vulnerability. Administrators can disable H.323 inspection for H.225 messages by issuing the no inspect h323 h225 command in class configuration submode in the policy map configuration. H.323 inspection for H.225 messages should be disabled for the workaround to be effective.

The following example shows how to disable H.323 inspection from the default policy-map:

ASA1000v(config)# policy-map global_policy
ASA1000v(config-pmap)# class inspection_default
ASA1000v(config-pmap-c)# no inspect h323 h225

If H.323 inspection for H.225 messages is required, there are no workarounds.

Obtaining Fixed Software

Cisco has released software updates that address the vulnerability described in this advisory. Prior to deploying software, customers are advised to consult their maintenance providers or check the software for feature set compatibility and known issues that are specific to their environments.

Customers may only install and expect support for feature sets they have purchased. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license at

Customers with Service Contracts

Customers with contracts should obtain software through their regular update channels. For most customers, software patches and bug fixes should be obtained through the Software Navigator on at

Customers Using Third-Party Support Organizations

Customers with Cisco products that are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers, should contact that organization for assistance with the appropriate course of action.

The effectiveness of any workaround or fix depends on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Because of the variety of affected products and releases, customers should consult their service providers or support organizations to ensure that any applied workaround or fix is the most appropriate in the intended network before it is deployed.

Customers Without Service Contracts

Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through Cisco Authorized partners, resellers, and distributors (authorized third-party vendors) but are unsuccessful in obtaining fixed software through their point of sale should obtain software patches and bug fixes by contacting the Cisco Technical Assistance Center (TAC):

  • +1 800 553 2447 (toll free from within North America)
  • +1 408 526 7209 (toll call from anywhere in the world)
  • e-mail:

Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a software patch or bug fix. Customers without service contracts should request a software patch or bug fix through the TAC.

Refer to Cisco Worldwide Contacts at for additional TAC contact information, including localized telephone numbers, instructions, and e-mail addresses for support in various languages.

Exploitation and Public Announcements

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.

This vulnerability was found during internal testing.

Status of This Notice: Final


A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.


This advisory is posted on Cisco Security at the following link:

Additionally, a text version of this advisory is clear signed with the Cisco PSIRT PGP key and circulated among the following e-mail addresses:


Future updates of this advisory, if any, will reside on but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.

Revision History

Revision 1.0 2013-January-16 Initial public release.

Cisco Security Procedures

Complete information about reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco is available on at This web page includes instructions for press inquiries regarding Cisco Security Advisories. All Cisco Security Advisories are available at
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