navbarPDF
Strip_SecurityNotices

Cisco Applied Mitigation Bulletin: Identifying and Mitigating Exploitation of the CiscoWorks TFTP Directory Traversal Vulnerability

Document ID: 110288

http://www.cisco.com/warp/public/707/cisco-amb-20090520-cw.shtml

Revision 1.0

For Public Release 2009 May 20 1600 UTC (GMT)


Please provide your feedback on this document.


Contents

Cisco Response
Device-Specific Mitigation and Identification
Additional Information
Revision History
Cisco Security Procedures
Related Information

Cisco Response

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

Vulnerability Characteristics

CiscoWorks Common Services contains a vulnerability that could allow a remote, unauthenticated attacker to access application and host operating system files. This vulnerability can be exploited remotely without authentication and without end-user interaction. Successful exploitation of this vulnerability may allow arbitrary code execution or information disclosure, which could enable an attacker to learn information about the affected device or network. Attempts to exploit this vulnerability could result in a denial of service condition. The attack vector for exploitation is through TFTP packets using UDP port 69.

This vulnerability has been assigned CVE identifier CVE-2009-1161.

Information about vulnerable, unaffected, and fixed software is available in the PSIRT Security Advisory, which is available at the following link: http://www.cisco.com/warp/public/707/cisco-sa-20090520-cw.shtml.

Mitigation Technique Overview

Cisco devices provide several countermeasures for this vulnerability. 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 infrastructure access control lists (iACLs). This protection mechanism filters and drops packets that are attempting to exploit this vulnerability.

Effective exploit prevention can also be provided by the Cisco ASA 5500 Series Adaptive Security Appliance, the Cisco PIX 500 Series Security Appliance, and the Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers using transit access control lists (tACLs). 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 this vulnerability.

Cisco IOS NetFlow flow records can provide visibility into network-based exploitation attempts.

Cisco IOS Software, Cisco ASA appliances, Cisco PIX security appliances, and FWSM firewalls can provide visibility through syslog messages and the counter values displayed in the output from show commands.

The Cisco Security Monitoring, Analysis, and Response System (Cisco Security MARS) appliance can also provide visibility through incidents, queries, and event reporting.

Risk Management

Organizations are advised to follow their standard risk evaluation and mitigation processes to determine the potential impact of this vulnerability. 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: Infrastructure Access Control Lists

To protect infrastructure devices and minimize the risk, impact, and effectiveness of direct infrastructure attacks, administrators are advised to deploy infrastructure access control lists (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 TFTP packets on UDP port 69 that are sent to affected devices. In the following example, 192.168.60.0/24 is the IP address space that is used by the affected devices, and the host at 192.168.100.1 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. In addition, insure that access is provided to the affected devices from all network devices that require TFTP services. 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.

Additional information about iACLs is in 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 port
  !

  permit udp host 192.168.100.1 192.168.60.0 0.0.0.255 eq 69

  !
  !-- The following vulnerability-specific access control entry
  !-- (ACE) can aid in identification of attacks
  !

  deny udp any 192.168.60.0 0.0.0.255 eq 69

  !
  !-- Explicit deny ACE for traffic sent to addresses configured within
  !-- the infrastructure address space
  !

  deny ip any 192.168.60.0 0.0.0.255
  
!
  !-- Permit/deny all other Layer 3 and Layer 4 traffic in accordance
  !-- with existing security policies and configurations
  !
!-- Apply iACL to interfaces in the ingress direction
!

interface GigabitEthernet0/0
 ip access-group Infrastructure-ACL-Policy in

  

Note 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 command no ip unreachables. ICMP unreachable rate limiting can be changed from the default using the global configuration command ip icmp rate-limit unreachable interval-in-ms.

Identification: Infrastructure Access Control Lists

After the administrator applies the iACL to an interface, the show ip access-lists command will identify the number of TFTP packets on UDP port 69 that have been filtered on interfaces on which the iACL is applied. Administrators should investigate filtered packets to determine whether they are attempts to exploit this vulnerability. Example output for show ip access-lists Infrastructure-ACL-Policy follows:

router# show ip access-lists Infrastructure-ACL-Policy
Extended IP access list Infrastructure-ACL-Policy
    10 permit udp host 192.168.100.1 192.168.60.0 0.0.0.255 eq tftp (435 matches)
    20 deny udp any 192.168.60.0 0.0.0.255 eq tftp  (13 matches)
    30 deny ip any 192.168.60.0 0.0.0.255 (9 matches)
router#

In the preceding example, access list Infrastructure-ACL-Policy has dropped 13 TFTP packets on UDP port 69 (tftp) for access control list entry (ACE) line 20.

For additional information about investigating incidents using ACE counters and syslog events, reference the Identifying Incidents Using Firewall and IOS Router Syslog Events Applied Intelligence white paper.

Administrators can use Embedded Event Manager to provide instrumentation when specific conditions are met, such as ACE counter hits. The Applied Intelligence white paper Embedded Event Manager in a Security Context provides additional details about how to use this feature.

Identification: Access List Logging

The log and log-input access control list (ACL) option will cause packets that match specific ACEs to be logged. The log-input option enables logging of the ingress interface in addition to the packet source and destination IP addresses and ports.

Caution: Access control list logging can be very CPU intensive and must be used with extreme caution. Factors that drive the CPU impact of ACL logging are log generation, log transmission, and process switching to forward packets that match log-enabled ACEs.

For Cisco IOS Software, the ip access-list logging interval interval-in-ms command can limit the effects of process switching induced by ACL logging. The logging rate-limit rate-per-second [except loglevel] command limits the impact of log generation and transmission.

The CPU impact from ACL logging can be addressed in hardware on the Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers with Supervisor Engine 720 or Supervisor Engine 32 using optimized ACL logging.

For additional information about the configuration and use of ACL logging, reference the Understanding Access Control List Logging Applied Intelligence white paper.

Cisco IOS NetFlow

Identification: Traffic Flow Identification Using NetFlow Records

Administrators can configure Cisco IOS NetFlow on Cisco IOS routers and switches to aid in the identification of traffic flows that may be attempts to exploit the vulnerability. Administrators are advised to investigate flows to determine whether they are attempts to exploit the vulnerability or whether they are legitimate traffic flows.

router# show ip cache flow
IP packet size distribution (32736 total packets):
   1-32   64   96  128  160  192  224  256  288  320  352  384  416  448  480
   .089 .556 .353 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

    512  544  576 1024 1536 2048 2560 3072 3584 4096 4608
   .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 278544 bytes
  124 active, 3972 inactive, 18349 added
  341664 ager polls, 0 flow alloc failures
  Active flows timeout in 30 minutes
  Inactive flows timeout in 15 seconds
IP Sub Flow Cache, 34056 bytes
  0 active, 1024 inactive, 0 added, 0 added to flow
  0 alloc failures, 0 force free
  1 chunk, 1 chunk added
  last clearing of statistics never
Protocol         Total    Flows   Packets Bytes  Packets Active(Sec) Idle(Sec)
--------         Flows     /Sec     /Flow  /Pkt     /Sec     /Flow     /Flow
TCP-WWW             99      0.0        13    40      0.0       0.0      15.4
TCP-BGP          17517      0.0         1    69      0.0       2.7      15.3
TCP-other          285      0.0         8    40      0.0       0.0      15.5
UDP-NTP              1      0.0         1    29      0.0       0.0      15.3
UDP-TFTP            87      0.0         3    28      0.0       0.0      15.5
UDP-other          206      0.0        10    28      0.0       0.0      15.5
ICMP                30      0.0        39    56      0.0       0.3      15.5
Total:           18225      0.0         1    61      0.0       2.6      15.3

SrcIf         SrcIPaddress    DstIf         DstIPaddress    Pr SrcP DstP  Pkts
Et0/0         192.168.139.166 Et0/1         192.168.206.68  06 F6AF 4E72     8 
Et0/0         192.168.1.40    Et0/0         192.168.85.93   11 4E50 250E     3 
Et0/0         192.168.0.122   Et0/1         192.168.60.113  06 A67B 0050    23 
Et0/0         192.168.255.20  Et0/1         192.168.60.255  11 799B 0045     5 
Et0/0         192.168.18.15   Et0/1         192.168.60.205  11 A31C 0045     3 
Et0/0         192.168.240.104 Et0/0         192.168.37.168  06 0C86 8047     5 
Et0/0         192.0.2.1       Local         192.0.2.2       06 811B 00B3     2 
Et0/0         192.168.129.180 Et0/0         192.168.92.129  06 CF89 6995    13 
Et0/0         192.168.0.216   Et0/1         192.168.60.233  06 9444 01BB     1 
Et0/0         192.168.0.113   Et0/1         192.168.60.140  06 354B 01BB     2 
Et0/0         192.168.0.208   Et0/1         192.168.60.103  06 059F 0050    28 
Et0/0         192.168.0.198   Et0/1         192.168.60.198  06 A486 01BB     2 
Et0/0         192.168.159.227 Et0/0         192.168.255.250 06 A06C 8F7C    11 
Et0/0         192.168.18.248  Et0/0         192.168.209.2   11 B215 D644     2 
Et0/0         192.168.207.220 Et0/0         192.168.209.35  11 EE87 31C2    10 
Et0/0         192.168.0.77    Et0/1         192.168.60.247  06 32EF 0050    10 
Et0/0         192.168.0.240   Et0/1         192.168.60.20   06 A316 01BB     3 
Et0/0         192.168.146.58  Et0/1         192.168.60.214  11 A413 0045     1 
Et0/0         192.168.0.227   Et0/1         192.168.60.177  06 DF6C 01BB     2 
Et0/0         192.168.0.146   Et0/1         192.168.60.93   06 8E77 01BB     6 
Et0/0         192.168.0.127   Et0/1         192.168.60.59   06 0FE9 0050    25 
Et0/0         192.168.225.244 Local         192.168.60.1    11 2967 0045     1 
Et0/0         192.168.0.76    Et0/1         192.168.60.131  06 2F1E 0050    33 
Et0/0         192.168.241.66  Et0/1         192.168.60.203  11 7AC4 0045     3 
Et0/0         192.168.208.227 Et0/1         192.168.60.158  11 F81A 0045     4 
Et0/0         192.168.253.214 Et0/0         192.168.57.1    06 89C2 6543     3 
Et0/0         192.168.88.77   Et0/1         192.168.60.164  11 A0AE 0045     4 
Et0/0         192.168.17.123  Et0/0         192.168.244.101 11 9762 C77B     2 
Et0/0         192.168.255.69  Et0/1         192.168.60.80   11 0B53 0045     6 
Et0/0         192.168.0.53    Et0/1         192.168.60.215  06 082E 0050    30 
Et0/0         192.168.163.175 Et0/1         192.168.60.167  11 0B36 0045     2 
Et0/0         192.168.174.128 Et0/0         192.168.235.9   11 99AF B3F1     7 
Et0/0         192.168.194.152 Et0/0         192.168.85.59   06 5760 33EA     5 
Et0/0         192.168.97.137  Et0/0         192.168.49.202  11 3AAD D2AD    13 
router#

In the preceding example, there are multiple flows for TFTP on UDP port 69 (hex value 0045).

This traffic is sent to addresses within the 192.168.60.0/24 address block which is used by affected devices. The packets in these flows may be spoofed and may indicate an attempt to exploit this vulnerability. Administrators are advised to compare these flows to baseline utilization for TFTP traffic sent on UDP port 69 and also investigate the flows to determine whether they are sourced from untrusted hosts or networks.

To view only the traffic flows for TFTP packets on UDP 69 (hex value 0045), the command show ip cache flow | include SrcIf|_11_.*0045 will display the related NetFlow records as shown here:

router# show ip cache flow | include SrcIf|_11_.*0045
SrcIf         SrcIPaddress    DstIf         DstIPaddress    Pr SrcP DstP  Pkts
Et0/0         192.168.255.20  Et0/1         192.168.60.255  11 799B 0045     5 
Et0/0         192.168.18.15   Et0/1         192.168.60.205  11 A31C 0045     3 
Et0/0         192.168.146.58  Et0/1         192.168.60.214  11 A413 0045     1 
Et0/0         192.168.225.244 Local         192.168.60.1    11 2967 0045     1 
Et0/0         192.168.241.66  Et0/1         192.168.60.203  11 7AC4 0045     3 
Et0/0         192.168.208.227 Et0/1         192.168.60.158  11 F81A 0045     4 
Et0/0         192.168.88.77   Et0/1         192.168.60.164  11 A0AE 0045     4 
Et0/0         192.168.255.69  Et0/1         192.168.60.80   11 0B53 0045     6 
Et0/0         192.168.163.175 Et0/1         192.168.60.167  11 0B36 0045     2 
router#

Cisco ASA, PIX, and 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 this vulnerability when the attack originates from a trusted source address.

The tACL policy denies unauthorized TFTP packets on UDP port 69 that are sent to affected devices. In the following example, 192.168.60.0/24 is the IP address space that is used by the affected devices, and the host at 192.168.100.1 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.

Additional information about tACLs is in Transit Access Control Lists: Filtering at Your Edge.


!
!-- Include any explicit permit statements for trusted sources
!-- that require access on the vulnerable port
!

access-list tACL-Policy extended permit udp host 192.168.100.1 192.168.60.0 255.255.255.0 eq 69

!
!-- The following vulnerability-specific access control entry
!-- (ACE) can aid in identification of attacks
!

access-list tACL-Policy extended deny udp any 192.168.60.0 255.255.255.0 eq 69

!
!-- Permit/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 any

!
!-- Apply tACL to interface(s) in the ingress direction
!

access-group tACL-Policy in interface outside

Identification: Transit Access Control Lists

After the tACL has been applied to an interface, administrators can use the show access-list command to identify the number of TFTP packets on UDP port 69 that have been filtered. Administrators are advised to investigate filtered packets to determine whether they are attempts to exploit this vulnerability. Example output for show access-list tACL-Policy follows:

firewall# show access-list tACL-Policy
access-list tACL-Policy; 3 elements
access-list tACL-Policy line 1 extended permit udp host 192.168.100.1 192.168.60.0 255.255.255.0 eq tftp (hitcnt=50)
access-list tACL-Policy line 2 extended deny udp any 192.168.60.0 255.255.255.0 eq tftp  (hitcnt=53)
access-list tACL-Policy line 3 extended deny ip any any (hitcnt=19)
firewall#

In the preceding example, access list tACL-Policy has dropped 53 TFTP packets on UDP port 69 (tftp) received from an untrusted host or network. In addition, syslog message 106023 can provide valuable information, which includes the source and destination IP address, the source and destination port numbers, and the IP protocol for the denied packet.

Identification: Firewall Access List Syslog Messages

Firewall syslog message 106023 will be generated for packets denied by an access control entry (ACE) that does not have the log keyword present. Additional information about this syslog message is in Cisco Security Appliance System Log Message - 106023.

Information about configuring syslog for the Cisco ASA 5500 Series Adaptive Security Appliance or the Cisco PIX 500 Series Security Appliance is in Monitoring the Security Appliance - Configuring and Managing Logs. Information about configuring syslog on the FWSM for Cisco Catalyst 6500 Series switches and Cisco 7600 Series routers is in Monitoring the Firewall Services Module.

In the following example, the show logging | grep regex command extracts syslog messages from the logging buffer on the firewall. These messages provide additional information about denied packets that could indicate potential attempts to exploit the vulnerability that is described in this document. It is possible to use different regular expressions with the grep keyword to search for specific data in the logged messages.

Additional information about regular expression syntax is in Creating a Regular Expression.

firewall# show logging | grep 106023
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:10.67.42.189/12633 
	dst inside:192.168.60.7/69 by access-group "tACL-Policy"
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:10.193.104.28/19615 
	dst inside:192.168.60.1/69 by access-group "tACL-Policy"
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:10.156.197.247/34067 
	dst inside:192.168.60.31/69 by access-group "tACL-Policy"
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:192.168.155.147/46897 
	dst inside:192.168.60.22/69 by access-group "tACL-Policy"
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:10.87.194.109/16790 
	dst inside:192.168.60.24/69 by access-group "tACL-Policy"
Apr 20 2009 16:27:43: %ASA-4-106023: Deny udp src outside:10.161.139.118/26622 
	dst inside:192.168.60.10/69 by access-group "tACL-Policy"
firewall#

In the preceding example, the messages logged for the tACL tACL-Policy show TFTP packets for UDP port 69 sent to the address block assigned to the affected devices.

Additional information about syslog messages for ASA and PIX security appliances is in Cisco Security Appliance System Log Messages. Additional information about syslog messages for the FWSM is in Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Logging System Log Messages.

For additional information about investigating incidents using syslog events, reference the Identifying Incidents Using Firewall and IOS Router Syslog Events Applied Intelligence white paper.

Cisco Intrusion Prevention System

Mitigation: Cisco IPS Signature Event Actions

Administrators can use Cisco Intrusion Prevention System (IPS) appliances and services modules to provide threat detection and help prevent attempts to exploit the vulnerability that is described in this document. Beginning with signature update S256 for sensors running Cisco IPS version 6.x or 5.x, the vulnerability can be detected by signature 5510/0 (Signature Name: Cisco TFTPD Directory Traversal). Signature 5510/0 is not enabled by default, triggers a High severity event, has a signature fidelity rating (SFR) of 75, and is configured with a default event action of produce-alert.

This signature fires when a TFTP request is made by appending a ../ character string to the pathname. Firing of this signature may indicate a potential exploit of the vulnerability, but the nature of the signature may cause it to be triggered by events that are unrelated to exploits of this vulnerability.

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 vulnerability that is described in this document.

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 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.

Cisco IPS 5.x sensors that are deployed in inline protection mode require an event action configured on a per-signature basis. Alternatively, administrators can configure an override that can perform an event action for any signatures that are triggered and are calculated as a high-risk threat. Using an event action on sensors deployed in inline protection mode provides the most effective exploit prevention.

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

Identification: IPS Signature Events

Signature: 5510/0 Cisco TFTPD Directory Traversal

IPS#  show events alert | include 5510
evIdsAlert: eventId=1238718211601136119  severity=high vendor=Cisco 
  originator: 
    hostId: R3-A041-IPS4240
    appName: sensorApp
    appInstanceId: 428
  time: 2009/04/21 16:42:02 2009/04/21 11:42:02 CDT
   signature: description=Cisco TFTPD Directory Traversal id=5510 created=20050603 type=vulnerability version=S256 
    subsigId: 0
     sigDetails: ../
    marsCategory: Info/Misc
  interfaceGroup: vs0
  vlan: 0
  participants: 
    attacker: 
      addr: locality=OUT 192.168.208.63
      port: 32773
    target: 
      addr: locality=OUT 192.168.130.86
      port: 69
      os: idSource=unknown relevance=relevant type=unknown 
  triggerPacket: 
000000  00 18 73 17 9F E8 00 18  74 B5 A4 1A 08 00 45 00  ..s.....t.....E.
000010  00 31 00 00 40 00 3F 11  67 D5 C0 A8 D0 3F C0 A8  .1..@.?.g....?..
000020  82 56 80 05 00 45 00 1D  97 ED 00 01 2E 2E 2F 2E  .V...E......../.
000030  2E 2F 65 74 63 00 6E 65  74 61 73 63 69 69 00     ./etc.netascii.
  riskRatingValue: attackRelevanceRating=relevant targetValueRating=medium 70
  threatRatingValue: 70
  interface: ge0_3
  protocol: udp

Cisco Security Monitoring, Analysis, and Response System

Identification: Cisco Security Monitoring, Analysis, and Response System Incidents

The Cisco Security Monitoring, Analysis, and Response System (Cisco Security MARS) appliance can create incidents regarding events that are related to the vulnerability that is described in this document using IPS signature 5510/0 (Signature Name: Cisco TFTPD Directory Traversal). After the S256 dynamic signature update has been downloaded, using keyword NR-5510/0 for IPS signature 5510/0 and a query type of All Matching Event Raw Messages on the Cisco Security MARS appliance will provide a report that lists the incidents created by the IPS signature.

Beginning with the 4.3.1 and 5.3.1 releases of Cisco Security MARS appliances, support for the Cisco IPS dynamic signature updates feature has been added. This feature downloads new signatures from Cisco.com or from a local web server, correctly processes and categorizes received events that match those signatures, and includes them in inspection rules and reports. These updates provide event normalization and event group mapping, and they also enable the MARS appliance to parse new signatures from the IPS devices.

Caution: If dynamic signature updates are not configured, events that match these new signatures appear as unknown event type in queries and reports. Because MARS will not include these events in inspection rules, incidents may not be created for potential threats or attacks that occur within the network.

By default, this feature is enabled but requires configuration. If it is not configured, the following Cisco Security MARS rule will be triggered:

System Rule: CS-MARS IPS Signature Update Failure

When this feature is enabled and configured, administrators can determine the current signature version downloaded by MARS by selecting Help > About and reviewing the IPS Signature Version value.

Additional information about dynamic signature updates and instructions for configuring dynamic signature updates are available for the Cisco Security MARS 4.3.1 and 5.3.1 releases.

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.

Revision History

Revision 1.0

2009-May-20

Initial public release

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/en/US/products/products_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


Toolbar


Updated: May 20, 2009Document ID: 110288