Cisco Applied Mitigation Bulletin-
Cisco Response
This Applied Mitigation Bulletin is a companion document to the following PSIRT Security Advisories:
This document provides identification and mitigation techniques that administrators can deploy on Cisco network devices.
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Vulnerability Characteristics
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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 . This protection mechanism filters and drops packets that are attempting to exploit this vulnerability.
Effective use of Cisco Intrusion Prevention System (IPS) event actions provides visibility into and protection against attacks that attempt to exploit these vulnerabilities.
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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.
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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 ASA, Cisco ASASM, and Cisco FWSM Firewalls
- Cisco Intrusion Prevention System
- Sourcefire Intrusion Prevention System
- Cisco Ironport Cloud Security
Cisco IOS Routers and Switches
Mitigation: Infrastructure Access Control Lists
To protect infrastructure devices and minimize the risk, impact, and effectiveness of direct infrastructure attacks, administrators are advised to deploy iACLs to perform policy enforcement of traffic sent to infrastructure equipment. Administrators can construct an iACL by explicitly permitting only authorized traffic sent to infrastructure devices in accordance with existing security policies and configurations. For the maximum protection of infrastructure devices, deployed iACLs should be applied in the ingress direction on all interfaces to which an IP address has been configured. An iACL workaround cannot provide complete protection against this vulnerability when the attack originates from a trusted source address.
The iACL policy denies unauthorized IPv4 and IPv6 packets on and that are sent to affected devices. In the following example, 192.168.60.0/242001:DB8:1:60::/64 represent the IP address space that is used by the affected devices, and the host at 192.168.100.1 2001:DB8::100:1 is considered a trusted source that requires access to the affected devices. Care should be taken to allow required traffic for routing and administrative access prior to denying all unauthorized traffic. Whenever possible, infrastructure address space should be distinct from the address space used for user and services segments. Using this addressing methodology will assist with the construction and deployment of iACLs.
For additional information about iACLs, see Protecting Your Core: Infrastructure Protection Access Control Lists.
ip access-list extended Infrastructure-ACL-Policy
! !-- Include explicit permit statements for trusted sources that !-- require access on the vulnerable TCP and UDP ports ! ! !-- The following vulnerability-specific access control entries !-- (ACEs) can aid in identification of attacks ! ! !-- 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 ! deny ip any 192.168.60.0 0.0.0.255 ! ! !-- Create the corresponding IPv6 tACL ! ipv6 access-list IPv6-Infrastructure-ACL-Policy ! !-- Include explicit permit statements for trusted sources that !-- require access on the vulnerable TCP and UDP ports ! ! !-- The following vulnerability-specific ACEs can !-- aid in identification of attacks to global and !-- link-local addresses ! ! !-- Permit or deny all other Layer 3 and Layer 4 traffic in !-- accordance with existing security policies and configurations !-- and allow IPv6 neighbor discovery packets, which !-- include neighbor solicitation packets and neighbor !-- advertisement packets ! permit icmp any any nd-ns permit icmp any any nd-na ! !-- Explicit deny for all other IPv6 traffic ! deny ipv6 any 2001:DB8:1:60::/64 ! ! !-- Apply tACLs to interface in the ingress direction ! interface GigabitEthernet0/0 ip access-group Infrastructure-ACL-Policy in ipv6 traffic-filter IPv6-Infrastructure-ACL-Policy inNote that filtering with an interface access list will elicit the transmission of ICMP unreachable messages back to the source of the filtered traffic. Generating these messages could have the undesired effect of increasing CPU utilization on the device. In Cisco IOS Software, ICMP unreachable generation is limited to one packet every 500 milliseconds by default. ICMP unreachable message generation can be disabled using the interface configuration commands no ip unreachables and no ipv6 unreachables. ICMP unreachable rate limiting can be changed from the default using the global configuration commands ip icmp rate-limit unreachable interval-in-ms and ipv6 icmp error-interval interval-in-ms.
For information about how to use the Cisco IOS Software command line interface to gauge the effectiveness of the iACL, see the Cisco Security Intelligence Operations white paper Identifying the Effectiveness of Security Mitigations Using Cisco IOS Software.
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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.
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Show LessVersion Description Section Date 1 Alert History
Initial Release2014-March-05 16:02 GMT
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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 https://sec.cloudapps.cisco.com/security/center/resources/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.
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The security vulnerability applies to the following combinations of products.
Primary Products Cisco Cisco Wireless LAN Controller (WLC) 4.0 (.108, .155.0, .155.5, .179.8, .179.11, .196, .206.0, .217.0, .219.0) | 4.1 (Base, .171.0, .181.0, .185.0) | 4.2 (Base, .61.0, .99.0, .112.0, .117.0, .130.0, .173.0, .174.0, .176.0, .182.0) | 5.0 (.148.0, .148.2) | 5.1 (.151.0, .152.0, .160.0) | 5.2 (.157.0, .169.0) | 6.0 (Base, 182.0, 188.0, 196.0, 199.4, 202.0) | 7.0 (Base, 98.0, 98.218, 116.0, 220.0) | 7.1 (Base, 91.0) | 7.2 (Base, 103.0) | 7.3 (Base, .101.0, .112) | 7.4 (Base, 1.54, .100, .100.60, .110.0) | 7.5 (Base, .102.0)
Associated Products
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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 ALERTS AT ANY TIME.
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