Advisory ID: cisco-sa-20140219-fwsm
For Public Release 2014 February 19 16:00 UTC (GMT)
Vulnerability Scoring Details
Software Versions and Fixes
Obtaining Fixed Software
Exploitation and Public Announcements
Status of This Notice: Final
Cisco Security Procedures
The vulnerability is due to a race condition when releasing the memory allocated by the cut-through proxy function. An attacker could exploit this vulnerability by sending traffic to match the condition that triggers cut-through proxy authentication.
Cisco has released free software updates that address this vulnerability. Workarounds that mitigate the vulnerability are not available. This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140219-fwsm
Cisco FWSM Software has reached the end of software maintenance releases milestone. Cisco FWSM customers are encouraged to contact their Cisco representative for available replacement.
The following example shows a Cisco FWSM configured to authenticate traffic matching the access list SERVER_AUTH through the external AAA server called AuthOutbound. The configuration in the example is implemented with the match command.
FWSM/admin# show running-config aaa authentication| include match|include
aaa authentication match SERVER_AUTH inside AuthOutbound
The following example shows an equivalent configuration implemented with the include command.
FWSM/admin# show running-config aaa authentication| include match|include
aaa authentication include SERVER_AUTH inside AuthOutbound
The cut-through proxy function is not enabled by default on Cisco FWSM Software.
Determine the Running Software VersionTo determine the version of the Cisco FWSM software that is running on a device, administrators can issue the show version command, as shown in the following example:
FWSM> show version FWSM Firewall Version 4.0(16) [...]
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 Cisco ASDM window. The version notation is similar to the following example:
FWSM Version: 4.0(16)
Version information can also be obtained from the Cisco Catalyst 6500 Series Switch or the Cisco 7600 Series Router. To determine the version of Cisco FWSM Software that is running on a device, issue the show module command from Cisco IOS Software or Cisco Catalyst Operating System Software to identify which modules and submodules are installed on the system.
The following example shows a system with a Cisco FWSM (WS-SVC-FWM-1) installed in slot 2:
switch>show module Mod Ports Card Type Model Serial No. --- ----- -------------------------------------- ------------------ ----------- 1 16 SFM-capable 16 port 1000mb GBIC WS-X6516-GBIC SAL06334NS9 2 6 Firewall Module WS-SVC-FWM-1 SAD10360485 3 8 Intrusion Detection System WS-SVC-IDSM-2 SAD0932089Z 4 4 SLB Application Processor Complex WS-X6066-SLB-APC SAD093004BD 5 2 Supervisor Engine 720 (Active) WS-SUP720-3B SAL0934888E Mod MAC addresses Hw Fw Sw Status --- ---------------------------------- ------ ------------ ------------ ------- 1 0009.11e3.ade8 to 0009.11e3.adf7 5.1 6.3(1) 8.7(0.22)BUB Ok 2 0018.ba41.5092 to 0018.ba41.5099 4.0 7.2(1) 4.0(16) Ok 3 0014.a90c.9956 to 0014.a90c.995d 5.0 7.2(1) 7.0(4)E4 Ok 4 0014.a90c.66e6 to 0014.a90c.66ed 1.7 Unknown Unknown PwrDown 5 0013.c42e.7fe0 to 0013.c42e.7fe3 4.4 8.1(3) 12.2(33)SXH8 Ok [...]
After locating the correct slot, issue the show module <slot number> command to identify the software version that is running, as shown in the following example:
switch>show module 2 Mod Ports Card Type Model Serial No. --- ----- -------------------------------------- ------------------ ----------- 2 6 Firewall Module WS-SVC-FWM-1 SAD10360485 Mod MAC addresses Hw Fw Sw Status --- ---------------------------------- ------ ------------ ------------ ------- 2 0018.ba41.5092 to 0018.ba41.5099 4.0 7.2(1) 4.0(16) Ok [...]
The preceding example shows that the Cisco FWSM is running software version 4.0(16) as indicated by the Sw column.
If a Virtual Switching System (VSS) is used to allow two physical Cisco Catalyst 6500 Series Switches to operate as a single logical virtual switch, the show module switch all command can display the software version of all FWSMs that belong to switch 1 and switch 2. The output from this command will be similar to the output from show module <slot number> but will include module information for the modules in each switch in the VSS.
No other Cisco products are currently known to be affected by this vulnerability.
Cisco FWSM Software supports the cut-through proxy feature for AAA network access services.
A vulnerability in the cut-through proxy function of Cisco Firewall Services Module (FWSM) Software could allow an unauthenticated, remote attacker to cause a reload of the affected system.
Note: This vulnerability affects both routed and transparent firewall mode in both single and multiple context mode. This vulnerability can be triggered by IP version 4 (IPv4) traffic only. Transit traffic and traffic directed to the FWSM device can be used to trigger this vulnerability. Configurations that use an external AAA server or the Cisco FWSM local user database for AAA vulnerable.
This vulnerability is documented in Cisco bug ID CSCuj16824 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2014-0710.
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:
CSCuj16824 - Cisco FWSM Cut-Through Proxy Denial of Service Vulnerability
Calculate the environmental score of CSCuj16824
CVSS Base Score - 7.1
CVSS Temporal Score - 5.9
Successful exploitation of the vulnerability may cause the reload of an affected system. Repeated exploitation could result in a denial of service (DoS) condition.
When considering software upgrades, customers are advised to consult the Cisco Security Advisories, Responses, and Notices archive at http://www.cisco.com/go/psirt 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.The following table gives information on the release that fixes this vulnerability for each of the major release versions.
|CSCuj16824 - Cisco FWSM Cut-Through Proxy Denial of Service Vulnerability1
||Migrate to 3.2.x or later
||Migrate to 4.1 or later
1 This vulnerability does not affect Cisco FWSM Software releases prior to 3.1(21), 3.2(21), 4.0(16), and 4.1(6).
Note: Cisco FWSM Software has reached the end of software maintenance releases milestone. Cisco FWSM customers are encouraged to contact their Cisco representative for an available replacement.
There are no workarounds that mitigate this vulnerability other than disabling the cut-through proxy feature.
Cisco has released free 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 http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html.
Customers with contracts should obtain upgraded software through their regular update channels. For most customers, upgrades should be obtained through the Software Navigator on Cisco.com at http://www.cisco.com/cisco/software/navigator.html.
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 who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades 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: email@example.com
Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Customers without service contracts should request free upgrades through the TAC.
Refer to Cisco Worldwide Contacts at http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, instructions, and e-mail addresses for support in various languages.
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 the resolution of support cases.
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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 Cisco.com but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.
|Revision 1.0||2014-February-19||Initial public release|
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