Cisco Security Advisory
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The Cisco Firewall Services Module (FWSM) for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is affected by the following vulnerabilities:
- DCERPC Inspection Buffer Overflow Vulnerability
- DCERPC Inspection Denial Of Service Vulnerabilities
These vulnerabilities are not interdependent; a release that is affected by one vulnerability is not necessarily affected by the other.
Cisco has released software updates that address these vulnerabilities. There are no workarounds that mitigate these vulnerabilities.
Exploitation of these vulnerabilities could allow an unauthenticated, remote attacker to trigger a reload of the affected device, or to execute arbitrary commands. Repeated exploitation could result in a denial of service (DoS) condition.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20121010-fwsm
Note: The Cisco Catalyst 6500 Series ASA Services Module, and the Cisco ASA 5500 Series Adaptive Security Appliance may also be affected by these vulnerabilities.
The vulnerabilities affecting the Cisco Catalyst 6500 Series ASA Services Module and Cisco ASA 5500 Series Adaptive Security Appliance have been disclosed in a separate Cisco Security Advisory. The Advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20121010-asa
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The Cisco FWSM for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers is affected by multiple vulnerabilities. The affected versions of the Cisco FWSM varies depending on the specific vulnerability.
Vulnerable Products
Consult the "Software Versions and Fixes" section of this security advisory for more information about the affected versions.
DCERPC Inspection Buffer Overflow Vulnerability
The Cisco FWSM is vulnerable when DCERPC inspection is enabled. DCERPC inspection is not enabled by default.
DCERPC Inspection Denial Of Service Vulnerabilities
The Cisco FWSM is vulnerable when DCERPC inspection is enabled. DCERPC inspection is not enabled by default.
Checking Whether DCERPC Inspection Is Enabled
To determine if your FWSM configuration is affected by these vulnerabilities, issue the show service-policy | include dcerpc command.
The following example indicates a Cisco FWSM with DCERPC inspection enabled:
fwsm# show service-policy | include dcerpc
Inspect: dcerpc, packet 0, drop 0, reset-drop 0How to Determine the Running Software Version
To 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 what 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.Products Confirmed Not Vulnerable
With the exception of the Cisco Adaptive Security Appliance, and Cisco ASA Service Module, no other Cisco products are currently known to be affected by these vulnerabilities.
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The Cisco FWSM is a high-speed, integrated firewall module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers. The FWSM offers firewall services with stateful packet filtering and deep packet inspection.
The Cisco FWSM is affected by multiple vulnerabilities, which are described in the following sections:
DCERPC Inspection Buffer Overflow Vulnerability
DCERPC is a protocol widely used by Microsoft distributed client and server applications that allows software clients to execute programs on a server remotely.
A vulnerability exists in the code of the DCERPC inspection engine that would allow an unauthenticated, remote attacker to cause a reload of the affected system or to overflow the stack and possibly execute arbitrary commands. The vulnerability is due to insufficient validation of DCERPC packets within a valid DCERPC session. An attacker could exploit this vulnerability by sending a crafted DCERPC packet that will be inspected by the affected system.
Note: Only transit traffic can be used to exploit this vulnerability. This vulnerability affects both routed and transparent firewall mode in both single and multi-context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic.
This vulnerability is documented in Cisco bug ID CSCtr27522 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2012-4661.
DCERPC Inspection Denial Of Service Vulnerabilities
Two vulnerabilities exist in the DCERPC inspection engine that would allow an unauthenticated, remote attacker to cause a reload of the affected system. The vulnerabilities are due to insufficient validation of DCERPC packets within a valid DCERPC session. An attacker could exploit this vulnerability by sending a crafted DCERPC packet that will be inspected by the affected system.
Note: Only transit traffic can be used to exploit these vulnerabilities. These vulnerabilities affect both routed and transparent firewall mode in both single and multi-context mode. These vulnerabilities can be triggered by IPv4 and IPv6 traffic.
These vulnerabilities are documented in Cisco bug ID CSCtr27524 (registered customers only) and CSCtr27521 (registered customers only) and have been assigned CVE IDs CVE-2012-4662 and CVE-2012-4663, respectively.
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Administrators can mitigate these vulnerabilities by disabling the DCERPC inspection if it is not required.
No other workarounds exist to mitigate these vulnerabilities.
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When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses 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.
DCERPC Inspection Buffer Overflow Vulnerability
Vulnerability Major Release
First Fixed Release
DCERPC Inspection Buffer Overflow Vulnerability - CSCtr27522
3.1 Not Vulnerable
3.2 Not Vulnerable 4.0 Not Vulnerable
4.1 4.1(9)
DCERPC Inspection Denial Of Service Vulnerabilities
Vulnerability Major Release
First Fixed Release
DCERPC Inspection Denial Of Service Vulnerabilities - CSCtr27524 and CSCtr27521
3.1 Not Vulnerable
3.2 Not Vulnerable
4.0 Not Vulnerable
4.1 4.1(7)
Recommended Releases
The following table lists all recommended releases. These recommended releases contain the fixes for all vulnerabilities in this advisory. Cisco recommends upgrading to a release that is equal to or later than these recommended releases.
Major Release
Recommended Release
3.1 Not Vulnerable
3.2 Not Vulnerable
4.0 Not Vulnerable
4.1 4.1(9)
Software Download
Cisco FWSM Software can be downloaded from the Software Center on Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.htmlFor Cisco Catalyst 6500 Series ASA Services Module, navigate to Products > Cisco Interfaces and Modules > Cisco Services Modules >Cisco Catalyst 6500 Series Firewall Services Module > ASA Services Module (FWSM) Software. Please note that some of these versions are interim versions and can be found by expanding the Interim tab on the download page.
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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.
The vulnerabilities described in this security advisory were found during internal testing.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessRevision 1.0 2012-October-10 Initial public release
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