Products & Services
Support

Product Categories


Popular Downloads


Manage Software

How to Buy

For Home

Linksys Products Store
Linksys is now part of Belkin
Products for everyone

All Ordering Options

Training & Events Partners
Guest

Cisco Applied Mitigation Bulletin

Identifying and Mitigating Exploitation of the Cisco TelePresence Video Communication Server SIP Denial of Service Vulnerability

 
Threat Type:IntelliShield: Applied Mitigation Bulletin
IntelliShield ID:32409
Version:1
First Published:2014 January 22 16:00 GMT
Last Published:2014 January 22 16:00 GMT
Port: Not available
CVE:CVE-2014-0662
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
Related Resources:
View related IPS SignatureView related Alert
 
 
Version Summary:Cisco Applied Mitigation Bulletin initial public release.
 

Cisco Response

This Applied Mitigation Bulletin is a companion document to the PSIRT Security Advisory and provides identification and mitigation techniques that administrators can deploy on Cisco network devices.

Vulnerability Characteristics

Repeated attempts to exploit this vulnerability could result in a sustained DoS condition.

The attack vectors for exploitation are through IPv4 packets using the following protocols and ports:

  • SIP using TCP 5060
  • SIP using TCP 5061
  • SIP using UDP 5060
An attacker could exploit this vulnerability using spoofed packets.

This vulnerability has been assigned Common Vulnerabilities and Exposures (CVE) identifier CVE-2014-0662.

Mitigation Technique Overview

Cisco devices provide several countermeasures for these vulnerabilities. Administrators are advised to consider these protection methods to be general security best practices for infrastructure devices and the traffic that transits the network. This section of the document provides an overview of these techniques.

Cisco IOS Software can provide effective means of exploit prevention using the following methods:

  • Transit access control lists (tACLs)
  • Unicast Reverse Path Forwarding (uRPF)
  • IP source guard (IPSG)

These protection mechanisms filter and drop, as well as verify the source IP address of, packets that are attempting to exploit these vulnerabilities.

The proper deployment and configuration of IPSG provides an effective means of protection against spoofing attacks at the access layer.

Effective exploit prevention can also be provided by the Cisco ASA 5500 Series Adaptive Security Appliance, Cisco Catalyst 6500 Series ASA Services Module (ASASM), and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers using the following methods:

  • Transit access control lists (tACLs)
  • Unicast Reverse Path Forwarding (uRPF)

These protection mechanisms filter and drop, as well as verify the source IP address of, packets that are attempting to exploit this vulnerability.

Risk Management

Organizations are advised to follow their standard risk evaluation and mitigation processes to determine the potential impact of these vulnerabilities. Triage refers to sorting projects and prioritizing efforts that are most likely to be successful. Cisco has provided documents that can help organizations develop a risk-based triage capability for their information security teams. Risk Triage for Security Vulnerability Announcements and Risk Triage and Prototyping can help organizations develop repeatable security evaluation and response processes.

Device-Specific Mitigation and Identification

Caution: The effectiveness of any mitigation technique depends on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. As with any configuration change, evaluate the impact of this configuration prior to applying the change.

Specific information about mitigation and identification is available for these devices:

Cisco IOS Routers and Switches

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy transit access control lists (tACLs) to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against this vulnerability when the attack originates from a trusted source address.

The tACL policy denies unauthorized IPv4 packets on TCP ports 5060 and 5061 and UDP port 5060 that are sent to affected devices. In the following example, 192.168.60.0/24 and represents the IP address space that is used by the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic. Additional information about tACLs is in Transit Access Control Lists: Filtering at Your Edge.
!
!-- Include explicit permit statements for trusted sources that
!-- require access on the vulnerable TCP and UDP ports
!
access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 5060
access-list 150 permit tcp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 5061
access-list 150 permit udp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 5060
!
!-- The following vulnerability-specific access control entries
!-- (ACEs) can aid in identification of attacks
!
access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 5060
access-list 150 deny tcp any 192.168.60.0 0.0.0.255 eq 5061
access-list 150 deny udp any 192.168.60.0 0.0.0.255 eq 5060
!
!-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
!-- with existing security policies and configurations
!
!-- Explicit deny for all other IP traffic
!
access-list 150 deny ip any any
!
!
!-- Apply tACL to interface in the ingress direction
!
interface GigabitEthernet0/0
 ip access-group 150 in 

For information about how to use the Cisco IOS Software command-line interface to gauge the effectiveness of spoofing protection, see the Cisco Security Intelligence Operations white paper Identifying the Effectiveness of Security Mitigations Using Cisco IOS Software.

For information about how to use the Cisco IOS Software command-line interface to gauge the effectiveness of the spoofing protection methods, see the Cisco Security Intelligence Operations white paper Identifying the Effectiveness of Security Mitigations Using Cisco IOS Software.

Mitigation: Spoofing Protection

Unicast Reverse Path Forwarding

The vulnerabilities that are described in this document can be exploited by spoofed IP packets. Administrators can deploy and configure Unicast Reverse Path Forwarding (uRPF) as a protection mechanism against spoofing.

uRPF is configured at the interface level and can detect and drop packets that lack a verifiable source IP address. Administrators should not rely on uRPF to provide complete spoofing protection because spoofed packets may enter the network through a uRPF-enabled interface if an appropriate return route to the source IP address exists. Administrators are advised to take care to ensure that the appropriate uRPF mode (loose or strict) is configured during the deployment of this feature because it can drop legitimate traffic that is transiting the network. In an enterprise environment, uRPF may be enabled at the Internet edge and the internal access layer on the user-supporting Layer 3 interfaces.

For additional information about the configuration and use of uRPF, see the Understanding Unicast Reverse Path Forwarding Cisco Security Intelligence Operations white paper.

IP Source Guard

IP source guard (IPSG) is a security feature that restricts IP traffic on nonrouted, Layer 2 interfaces by filtering packets based on the DHCP snooping binding database and manually configured IP source bindings. Administrators can use IPSG to prevent attacks from an attacker who attempts to spoof packets by forging the source IP address and/or the MAC address. When properly deployed and configured, IPSG coupled with strict mode uRPF provides the most effective means of spoofing protection for the vulnerabilities that are described in this document.

Additional information about the deployment and configuration of IPSG is in Configuring DHCP Features and IP Source Guard.

For information about how to use the Cisco IOS Software command-line interface to gauge the effectiveness of spoofing protection, see the Cisco Security Intelligence Operations white paper Identifying the Effectiveness of Security Mitigations Using Cisco IOS Software.

Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls

Mitigation: Transit Access Control Lists

To protect the network from traffic that enters the network at ingress access points, which may include Internet connection points, partner and supplier connection points, or VPN connection points, administrators are advised to deploy tACLs to perform policy enforcement. Administrators can construct a tACL by explicitly permitting only authorized traffic to enter the network at ingress access points or permitting authorized traffic to transit the network in accordance with existing security policies and configurations. A tACL workaround cannot provide complete protection against these vulnerabilities when the attack originates from a trusted source address.

  !
  !-- Include explicit permit statements for trusted sources
  !-- that require access on the vulnerable TCP and UDP ports
  !
  access-list tACL-Policy extended permit tcp host 192.168.100.1 
     192.168.60.0 0.0.0.255 eq 5060
  access-list tACL-Policy extended permit tcp host 192.168.100.1 
     192.168.60.0 0.0.0.255 eq 5061
  access-list tACL-Policy extended permit udp host 192.168.100.1 
     192.168.60.0 0.0.0.255 eq 5060
  !
  !-- The following vulnerability-specific access control entries
  !-- (ACEs) can aid in identification of attacks
  !
  access-list tACL-Policy extended deny tcp any 192.168.60.0 0.0.0.255 eq 5060
  access-list tACL-Policy extended deny tcp any 192.168.60.0 0.0.0.255 eq 5061
  access-list tACL-Policy extended deny udp any 192.168.60.0 0.0.0.255 eq 5060
  !
  !-- Permit or deny all other Layer 3 and Layer 4 traffic in accordance
  !-- with existing security policies and configurations
  !
  !-- Explicit deny for all other IP traffic
  !
  access-list tACL-Policy extended deny ip any 192.168.60.0 0.0.0.255
  !
  !
  !-- Apply tACL to interfaces in the ingress direction
  !
  access-group tACL-Policy in interface outside

For information about using the Cisco firewall command-line interface to gauge the effectiveness of tACLs, see the Cisco Security Intelligence Operations white paper Identification of Security Exploits with Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls.

Mitigation: Spoofing Protection Using Unicast Reverse Path Forwarding

The vulnerabilities that are described in this document can be exploited by spoofed IP packets. Administrators can deploy and configure uRPF as a protection mechanism against spoofing.

uRPF is configured at the interface level and can detect and drop packets that lack a verifiable source IP address. Administrators should not rely on uRPF to provide complete spoofing protection because spoofed packets may enter the network through a uRPF-enabled interface if an appropriate return route to the source IP address exists. In an enterprise environment, uRPF may be enabled at the Internet edge and at the internal access layer on the user-supporting Layer 3 interfaces.

For additional information about the configuration and use of uRPF, see the Cisco Security Appliance Command Reference for ip verify reverse-path and the Understanding Unicast Reverse Path Forwarding Cisco Security Intelligence Operations white paper.

For information on how to use the firewall command-line interface to gauge the effectiveness of spoofing protection, see the Cisco Security Intelligence Operations white paper Identification of Security Exploits with Cisco ASA, Cisco ASASM, and Cisco FWSM Firewalls.

Mitigation: Cisco IPS Signature Table

Administrators can use the Cisco IPS appliances and services modules to provide threat detection and help prevent attempts to exploit several of the vulnerabilities described in this document. The following table provides an overview of CVE identifiers and the respective Cisco IPS signatures that will trigger events on potential attempts to exploit these vulnerabilities.

CVE ID Signature Release Signature ID Signature Name Enabled Severity Fidelity* Notes
CVE-2014-0662 S764 3571-0 Cisco TelePresence Video Communications Service SIP Denial of Service No Medium 70

* Fidelity is also referred to as Signature Fidelity Rating (SFR) and is the relative measure of the accuracy of the signature (predefined). The value ranges from 0 through 100 and is set by Cisco Systems, Inc.

Administrators can configure Cisco IPS sensors to perform an event action when an attack is detected. The configured event action performs preventive or deterrent controls to help protect against an attack that is attempting to exploit the vulnerabilities listed in the preceding table.

Cisco IPS sensors are most effective when deployed in inline protection mode combined with the use of an event action. Automatic Threat Prevention for Cisco IPS 7.x and 6.x sensors that are deployed in inline protection mode provides threat prevention against an attack that is attempting to exploit the vulnerability that is described in this document. Threat prevention is achieved through a default override that performs an event action for triggered signatures with a riskRatingValue greater than 90.

For additional information about the risk rating and threat rating calculation, see Risk Rating and Threat Rating: Simplify IPS Policy Management.

For information about using Cisco Security Manager to view the activity from a Cisco IPS sensor, see the Cisco Security Intelligence Operations white paper Identification of Malicious Traffic Using Cisco Security Manager.

Additional Information

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

Cisco Security Procedures

Complete information on reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco, is available on Cisco's worldwide website at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.

Related Information

  • Cisco Applied Mitigation Bulletins
  • Cisco Security Intelligence Operations
  • Cisco Security IntelliShield Alert Manager Service
  • Cisco Guide to Harden Cisco IOS Devices
  • Cisco IOS NetFlow - Home Page on Cisco.com
  • Cisco IOS NetFlow White Papers
  • NetFlow Performance Analysis
  • Cisco Network Foundation Protection White Papers
  • Cisco Network Foundation Protection Presentations
  • A Security-Oriented Approach to IP Addressing
  • Cisco Firewall Products - Home Page on Cisco.com
  • Cisco Catalyst 6500 Series ASA Services Module
  • Unicast Reverse Path Forwarding Enhancements for the Internet Service Provider
  • Cisco Intrusion Prevention System
  • Cisco IPS Signature Downloads
  • Cisco IPS Signature Search Page
  • Cisco Security Manager
  • Common Vulnerabilities and Exposures (CVE)
  • Subscribe to Cisco Applied Mitigation Bulletins
  •  
    Alert History
     
    Initial Release


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

    Primary Products:
    CiscoCisco TelePresence Video Communication Server (VCS) X5.2 Base | X6.0 Base | X6.1 Base | X7.0 .0, .1, .2, .3 | X7.1 Base | X7.2 Base, .1, .2

    Associated Products:
    N/A




    Alerts and bulletins on the Cisco Security Intelligence Operations Portal are highlighted by analysts in the Cisco Threat Operations Center and represent a subset of the comprehensive content that is available through Cisco Security IntelliShield Alert Manager Service. This customizable threat and vulnerability alert service provides security staff with access to timely, accurate, and credible information about threats and vulnerabilities that may affect their environment.


    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.
    Powered by  IntelliShield