Cisco Security Advisory: Multiple Vulnerabilities in Firewall Services Module

2007-02-15T00:00:00
ID SECURITYVULNS:DOC:16081
Type securityvulns
Reporter Securityvulns
Modified 2007-02-15T00:00:00

Description

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1

Cisco Security Advisory: Multiple Vulnerabilities in Firewall Services Module

Advisory ID: cisco-sa-20070214-fwsm

http://www.cisco.com/warp/public/707/cisco-sa-20070214-fwsm.shtml

Revision 1.0

For Public Release 2007 February 14 1600 UTC (GMT)


Summary

Multiple vulnerabilities exist in the Cisco Firewall Services Module (FWSM). These vulnerabilities occur in the processing of specific Hypertext Transfer Protocol (HTTP), Secure HTTP (HTTPS), Session Initiation Protocol (SIP), and Simple Network Management Protocol (SNMP) traffic. If verbose logging is enabled for debugging purposes, a vulnerability exists when the FWSM processes packets destined to itself. All of these vulnerabilities may result in a reload of the device.

An additional vulnerability is included in this advisory in which the manipulation of access control lists (ACLs) that make use of object groups may corrupt the ACL and create a situation where unwanted traffic may be permitted or desirable traffic may be blocked.

These vulnerabilities are independent of each other; a release that is affected by one vulnerability is not necessarily affected by the others.

There are workarounds for some of the vulnerabilities disclosed in this advisory.

Cisco has made free software available to address this issue for affected customers.

This advisory is posted at http://www.cisco.com/warp/public/707/cisco-sa-20070214-fwsm.shtml

Affected Products

The vulnerabilities described in this document apply to the FWSM. The companion advisory http://www.cisco.com/warp/public/707/cisco-sa-20070214-pix.shtml contains information about similar vulnerabilities that affect the Cisco PIX 500 Series Security Appliances and the Cisco ASA 5500 Series Adaptive Security Appliances.

Vulnerable Products +------------------

The following table indicates which software releases for the Cisco FWSM are affected and under what conditions:

+---------------------------------------------------------------------+ | Vulnerability | Only affected | Vulnerable | Versions | Cisco Bug | | Name | if... | by | affected | ID | | | | default? | | | |---------------+----------------+------------+----------+------------| | | Enhanced | | | | | 1. Enhanced | inspection of | | All 3.x | | | Inspection of | HTTP traffic | | software | | | Malformed | is enabled | No | releases | CSCsd75794 | | HTTP Traffic | through the | | prior to | | | May Cause | command | | 3.1 | | | Reload | "inspect http | | (3.24) | | | | <appfw>" | | | | |---------------+----------------+------------+----------+------------| | | SIP inspection | | | | | | is enabled | | All | | | | through the | | software | | | | command "fixup | | releases | | | 2. Inspection | protocol sip" | | prior to | | | of Malformed | (in FWSM | Yes for | 2.3 | | | SIP Messages | software 2.x | 2.x and no | (4.12) | CSCsg80915 | | May Cause | and before) or | for 3.x | and all | | | Reload | through the | | 3.x | | | | command | | releases | | | | "inspect sip" | | prior to | | | | (in FWSM | | 3.1 | | | | software 3.x | | (3.24) | | | | and later) | | | | |---------------+----------------+------------+----------+------------| | | Logging at | | | | | | "debugging" | | | | | 3. Processing | level | | All 3.x | | | of Packets | (regardless of | | software | | | Destined to | the logging | No | releases | CSCse85707 | | the FWSM May | destination) | | prior to | | | Cause Reload | and syslog | | 3.1(3.3) | | | | message 710006 | | | | | | is enabled | | | | |---------------+----------------+------------+----------+------------| | | Network access | | | | | | authentication | | | | | 4. Processing | is enabled | | All 3.x | | | of Malformed | through the | | software | | | HTTPS Traffic | "aaa | No | releases | CSCsg50228 | | May Cause | authentication | | prior to | | | Reload | match" or "aaa | | 3.1 | | | | authentication | | (3.18) | | | | include" | | | | | | commands | | | | |---------------+----------------+------------+----------+------------| | | Network access | | | | | | authentication | | | | | | is enabled | | | | | 5. Processing | through the | | All 3.x | | | of Long HTTP | "aaa | No | releases | CSCsd91268 | | Requests May | authentication | | prior to | | | Cause Reload | match" or "aaa | | 3.1(2) | | | | authentication | | | | | | include" | | | | | | commands | | | | |---------------+----------------+------------+----------+------------| | 6. Processing | HTTPS server | | All 3.x | | | HTTPS Traffic | is enabled | | releases | | | May Cause a | through the | No | prior to | CSCsf29974 | | Reload | "http server | | 3.1 | | | | enable" | | (3.11) | | | | command | | | | |---------------+----------------+------------+----------+------------| | | SNMP traffic | | | | | | from a | | | | | | particular IP | | | | | | address is | | | | | 7. Processing | permitted | | All 3.x | | | of Malformed | through the | | releases | | | SNMP Requests | command | No | prior to | CSCse52679 | | May Cause a | "snmp-server | | 3.1(3.1) | | | Reload | host | | | | | | <interface | | | | | | name> <IP | | | | | | address of | | | | | | SNMP server>" | | | | |---------------+----------------+------------+----------+------------| | | | | All | | | | | | software | | | 8. | ACL makes use | | releases | | | Manipulation | of object | | prior to | CSCse60868 | | of ACL May | groups and ACL | No | 2.3(4.7) | and | | Cause ACL | is manipulated | | and all | CSCse99740 | | Corruption | by an | | 3.x | | | | administrator | | releases | | | | | | prior to | | | | | | 3.1(3.1) | | +---------------------------------------------------------------------+

The relationship between the vulnerabilities described in this advisory and the equivalent vulnerabilities in the Cisco PIX 500 Series Security Appliances and Cisco ASA 5500 Series Adaptive Security Appliances is given in the following table. If a vulnerability discussed in this document is not present in this table, it does not affect the Cisco PIX 500 Series Security Appliances and Cisco ASA 5500 Series Adaptive Security Appliances.

+-------------------------------------------------------------+ | Vulnerability | PIX/ASA Bug | FWSM Bug | | | ID | ID | |---------------------------------+--------------+------------| | Enhanced Inspection of | | | | Malformed HTTP Traffic May | CSCsd75794 | CSCsd75794 | | Cause Reload | | | |---------------------------------+--------------+------------| | Inspection of Malformed SIP | CSCse27708 | | | Messages May Cause Reload | and | CSCsg80915 | | | CSCsd97077 | | +-------------------------------------------------------------+

To determine if you are running a vulnerable version of FWSM software, issue the "show module" command in IOS or CatOS to identify what modules and sub-modules are installed in the system.

The example below shows a system with a Firewall Service Module (WS-SVC-FWM-1) installed in slot 4.

6506-B#show module
Mod Ports Card Type                              Model              Serial No.
--- ----- -------------------------------------- ------------------ -----------
 1   48  SFM-capable 48 port 10/100/1000mb RJ45 WS-X6548-GE-TX     SAxxxxxxxxx
 4    6  Firewall Module                        WS-SVC-FWM-1       SAxxxxxxxxx
 5    2  Supervisor Engine 720 &#40;Active&#41;         WS-SUP720-BASE     SAxxxxxxxxx
 6    2  Supervisor Engine 720 &#40;Hot&#41;            WS-SUP720-BASE     SAxxxxxxxxx

After locating the correct slot, issue the "show module <slot number>" command to identify the version of software running:

6506-B#sho module 4
Mod Ports Card Type                              Model              Serial No.
--- ----- -------------------------------------- ------------------ -----------
 4    6  Firewall Module                        WS-SVC-FWM-1       SAxxxxxxxxx

Mod MAC addresses                       Hw    Fw           Sw           Status
--- ---------------------------------- ------ ------------ ------------ -------
 4  0003.e4xx.xxxx to 0003.e4xx.xxxx   3.0   7.2&#40;1&#41;       2.3&#40;1&#41;       Ok

In this example, the FWSM is running version 2.3(1) as indicated by the column under "Sw" above.

Note: recent versions of IOS will show the software version of each module in the output from the "show module" command so executing the "show module <slot number>" command is not necessary.

Alternatively, the information may also be gained directly from the FWSM through the "show version" command:

FWSM#show version

FWSM Firewall Version 2.3&#40;1&#41;

For customers managing their FWSM through the PIX Device Manager (PDM) or the Cisco Adaptive Security Device Manager (ASDM), log into the application, and the version may be found either in the table in the login window or in the upper left hand corner of the PDM/ASDM window indicated by a label similar to:

FWSM Version: 2.3(1)

Products Confirmed Not Vulnerable +--------------------------------

With the exception of the Cisco PIX 500 Series Security Appliances and the Cisco ASA 5500 Series Adaptive Security Appliances, no other Cisco products are known to be vulnerable to the issues described in this advisory.

Details

The Cisco Firewall Services Module is a high-speed, integrated firewall module for Catalyst 6500 series switches and Cisco 7600 series routers. It offers firewall services with stateful packet filtering and deep packet inspection.

Multiple vulnerabilities exist in certain versions of the FWSM software that may cause the device to unexpectedly reload or that may cause traffic to be permitted or denied contrary to the security policy in place.

  1. Enhanced Inspection of Malformed HTTP Traffic May Cause Reload +----------------------------------------------------------------

This vulnerability may cause a FWSM to reload when the FWSM performs enhanced inspection of HTTP requests, and a malformed HTTP request is inspected by the FWSM. The FWSM only performs enhanced inspection of HTTP traffic when the command "inspect http <appfw>" is present in the configuration (appfw is the name of a specific HTTP map.) This command is disabled by default.

Note: Enhanced inspection of HTTP traffic is what makes a configuration affected. Regular inspection of HTTP traffic (through the command "inspect http" without an HTTP map) will not make a configuration affected by this vulnerability.

For information on what enhanced inspection of HTTP traffic does, and how to configure it, please refer to the following URL:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/mod_icn/fwsm/fwsm_3_1/fwsm_cfg/inspct_f.htm#wp1390330

This vulnerability is documented in Cisco Bug ID CSCsd75794.

  1. Inspection of Malformed SIP Messages May Cause Reload +-------------------------------------------------------

This vulnerability may cause a FWSM to reload when a malformed SIP message is received and deep packet inspection of SIP messages is enabled through the command "fixup protocol sip" (in FWSM software 2.3.x and before) or through the command "inspect sip" (in FWSM software 3.x and later). SIP inspection is enabled by default in the 2.3.x series and before and is disabled by default in the 3.x series and later.

This vulnerability is documented in Cisco Bug ID CSCsg80915.

  1. Processing of Packets Destined to the FWSM May Cause Reload +-------------------------------------------------------------

This vulnerability will cause the FWSM to reload when trying to generate syslog message 710006. For this to happen the following two conditions must be satisfied:

  • The FWSM receives a packet for one of the device's IP addresses and the message is not one of the following protocols: TCP, UDP, ICMP, OSPF, Failover, PIM, IGMP, and ESP. The source of the packet is not relevant.
  • Logging must be enabled at a level high enough to generate syslog message 710006. By default this is debugging level (level 7). Please note that logging is disabled by default, and Cisco recommends customers only log at debugging level for debugging and troubleshooting purposes.

    Note: The documentation for the Cisco Security Monitoring, Analysis and Response System (CS-MARS) suggests logging at the debugging level so more events can be reported by the firewall.

For more information on syslog message 710006 please refer to the following document:

  • Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Logging Configuration and System Log Messages, 3.1 http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/mod_icn/fwsm/fwsm_3_1/fwsm_log/logmsgs.htm#wp1285757

This vulnerability is documented in Cisco Bug ID CSCse85707.

  1. Processing of Malformed HTTPS Requests May Cause Reload +---------------------------------------------------------

This vulnerability may cause the FWSM to reload when a user tries to access a web site and the network administrator has configured the device to authenticate users before granting them network access. This feature is known as "authentication for network access", or auth-proxy, and is enabled through the command "aaa authentication match" or "aaa authentication include".

The reload is actually triggered by a specific HTTPS request that is invalid, and therefore, unlikely to be generated by a regular web browser.

This vulnerability is documented in Cisco Bug ID CSCsg50228.

  1. Processing of Long HTTP Requests May Cause Reload +---------------------------------------------------

This vulnerability may also cause the FWSM to reload when the administrator has enabled "authentication for network access ("auth-proxy") through the commands "aaa authentication match" or "aaa authentication include". However, in this case, the HTTP request that causes the reload is valid, although it is not a normal request in the sense that the URL being requested is very long. A web browser could potentially generate such a request during regular browsing.

This vulnerability is documented in Cisco Bug ID CSCsd91268.

  1. Processing of HTTPS Traffic May Cause Reload +----------------------------------------------

This vulnerability may cause a FWSM to reload when the FWSM receives a particular type of HTTPS traffic directed to the FWSM itself. This is only a concern when the HTTPS server on the FWSM is enabled through the command "http server enable". This command is disabled by default.

Cisco is aware of a commercial vulnerability scanner that can generate the HTTPS traffic that triggers the reload. We are not aware of regular web browser traffic that triggers this bug.

This vulnerability is documented in Cisco Bug ID CSCsf29974.

  1. Processing of Malformed SNMP Requests May Cause a Reload +----------------------------------------------------------

This vulnerability may cause a FWSM to reload upon receipt of a malformed SNMP message from a trusted device. The trusted device must be allowed explicit SNMP poll access via the command "snmp-server host <interface name> <IP of trusted device>".

This vulnerability is documented in Cisco Bug IDs CSCse52679.

  1. Manipulation of ACL May Cause ACL Corruption +----------------------------------------------

This vulnerability may cause access control entries (ACEs) in an ACL to be evaluated out of order, or not to be evaluated. This ACL corruption is manifested, besides the obvious traffic implications, when the output from the "show access-list" command and the corresponding ACL shown by the "show running-config" command appear to be out of sync. Only a manual reload of the device will cause this condition to go away.

The ACL corruption occurs when an ACL that makes use of object groups is manipulated.

This vulnerability is documented in Cisco Bug IDs CSCse60868 and CSCse99740.

Vulnerability Scoring Details +----------------------------

Cisco is providing scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS).

Cisco will provide a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco PSIRT will set the bias in all cases to normal. Customers are encouraged to apply the bias parameter when determining the environmental impact of a particular vulnerability.

CVSS is a standards based scoring method that conveys vulnerability severity and helps determine urgency and priority of response.

Cisco has provided an FAQ to answer additional questions regarding CVSS at http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html.

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at http://intellishield.cisco.com/security/alertmanager/cvss.

CSCsd75794 - Enhanced inspection of Malformed HTTP traffic can crash device

CVSS Base Score: 3.3 Access Vector: Remote Access Complexity: Low Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.7 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCsg80915 - FWSM - Traceback when inspecting SIP packets

CVSS Base Score: 3.3 Access Vector: Remote Access Complexity: Low Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.7 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCse85707 - FWSM crash when printing debug level syslog 710006

CVSS Base Score: 2.7 Access Vector: Remote Access Complexity: High Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.2 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCsg50228 - FWSM ST MODE crashes at Thread NAME: uauth with RADIUS

CVSS Base Score: 2.7 Access Vector: Remote Access Complexity: High Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.2 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCsd91268 - FWSM crashes at Thread: uauth while using aaa with TACACS

CVSS Base Score: 3.3 Access Vector: Remote Access Complexity: Low Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.7 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCsf29974 - Crash in emweb/https thread

CVSS Base Score: 3.3 Access Vector: Remote Access Complexity: Low Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.7 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCse52679 - FWSM Crash in thread name SNMP

CVSS Base Score: 3.3 Access Vector: Remote Access Complexity: Low Authentication: Not Required Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete Impact Bias: Normal

CVSS Temporal Score: 2.7 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

CSCse60868 - Modifying an ACL with an object-group could cause ACL corruption and CSCse99740 - When removing network objects the existing ACL lines are not removed |

CVSS Base Score: 5.3 Access Vector: Remote Access Complexity: High Authentication: Not Required Confidentiality Impact: Complete Integrity Impact: Complete Availability Impact: None Impact Bias: Normal

CVSS Temporal Score: 4.4 Exploitability: Functional Remediation Level: Official Fix Report Confidence: Confirmed

Impact

In all cases, with the exception of the "Manipulation of ACL May Cause ACL Corruption" vulnerability, successful exploitation of any vulnerability may cause a reload of the affected device. Repeated exploitation could result in a sustained Denial-of-Service (DoS) condition.

In the case of the "Processing of Long HTTP Requests May Cause Reload" vulnerability (CSCsd91268), the reload occurs because a stack-based buffer is overflowed. In this case remote code execution may be possible.

In the case of the "Manipulation of ACL May Cause ACL Corruption" vulnerability, a device that becomes affected after an administrator manipulates an ACL with object groups may allow traffic that would normally be denied, or would deny traffic that would normally be permitted. If the ACL is used for other functions like NAT (policy NAT and NAT exemption), AAA (auth-proxy), control of access to the device (SSH, Telnet, HTTP, ICMP), then those functions may be adversely affected as well.

Software Version and Fixes

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center ("TAC") or your contracted maintenance provider for assistance.

Each row of the FWSM software table (below) describes one of the vulnerabilities described in this document. For each vulnerability the earliest possible release that contains the fix (the "First Fixed Release") and the anticipated date of availability for each are listed in the "First Fixed Release" column. A device running a release that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).

+-------------------------------------------------------------+ | Vulnerability | First Fixed Release | |---------------------------------+---------------------------| | 1. Enhanced Inspection of | 3.1(3.24) (the 2.3.x | | Malformed HTTP Traffic May | series are not affected) | | Cause Reload ( CSCsd75794) | | |---------------------------------+---------------------------| | 2. Inspection of Malformed SIP | 2.3(4.12) for the 2.3.x | | Messages May Cause Reload ( | series, and 3.1(3.24) for | | CSCsg80915) | the 3.x series | |---------------------------------+---------------------------| | 3. Processing of Packets | 3.1(3.3) (the 2.3.x | | Destined to the FWSM May Cause | series are not affected) | | Reload ( CSCse85707) | | |---------------------------------+---------------------------| | 4. Processing of Malformed | 3.1(3.18) (the 2.3.x | | HTTPS Requests May Cause Reload | series are not affected) | | ( CSCsg50228) | | |---------------------------------+---------------------------| | 5. Processing of Long HTTP | 3.1(1.9) (the 2.3.x | | Requests May Cause Reload ( | series are not affected) | | CSCsd91268) | | |---------------------------------+---------------------------| | 6. Processing HTTPS Traffic May | 3.1(3.11) (the 2.3.x | | Cause a Reload ( CSCsf29974) | series are not affected) | |---------------------------------+---------------------------| | 7. Processing of Malformed SNMP | 3.1(3.1) (the 2.3.x | | Requests May Cause a Reload ( | series are not affected) | | CSCse52679) | | |---------------------------------+---------------------------| | 8. Manipulation of ACL May | 2.3(4.7) for the 2.3.x | | Cause ACL Corruption ( | series, and 3.1(3.1) for | | CSCse60868) and ( CSCse99740) | the 3.x series | +-------------------------------------------------------------+

For the 2.3.x series, FWSM software version 2.3(4.12) contains the fixes for all the vulnerabilities described in this document.

For the 3.x series, FWSM software version 3.1(4) contains the fixes for all the vulnerabilities described in this document.

FWSM software is available for download from the following location on cisco.com:

http://www.cisco.com/pcgi-bin/tablebuild.pl/cat6000-fwsm?psrtdcat20e2

For FWSM release 2.3(4.12) please use the following link:

http://www.cisco.com/pcgi-bin/tablebuild.pl/FWSMPSIRT?psrtdcat20e2

Workarounds

Additional mitigations that can be deployed on Cisco devices within the network are available in the Cisco Applied Intelligence companion document for this advisory:

http://www.cisco.com/warp/public/707/cisco-air-20070214-firewall.shtml

  1. Enhanced Inspection of Malformed HTTP Traffic May Cause Reload +----------------------------------------------------------------

It is possible to mitigate this vulnerability by disabling enhanced inspection of HTTP traffic. Please note that disabling HTTP enhanced inspection will prevent the FWSM from protecting against specific attacks and other threats that may be associated with HTTP traffic. Enhanced inspection of HTTP traffic is disabled by removing the command "inspect http <appfw>" from the configuration, where appfw is the name of an HTTP map.

For further information about the "inspect http <appfw>" command, and the type of checks it performs on HTTP traffic, please see the documentation for this command at:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/mod_icn/fwsm/fwsm_3_1/fwsm_ref/i2.htm#wp1570030

Please note that the command "inspect http" (without an HTTP map) can be left in the configuration and the device will not be affected by this vulnerability.

  1. Inspection of Malformed SIP Messages May Cause Reload +-------------------------------------------------------

It is possible to mitigate this vulnerability by disabling deep packet inspection ("fixup" in software version prior to 3.x or "inspect" in software version 3.x and later) of SIP messages. Note, however, that this may have negative impact on devices terminating SIP sessions since SIP traffic will no longer undergo stateful application inspection, and devices which terminate sessions for this protocol will be exposed to packets that may cause these devices to crash or become compromised.

If you are running a 3.x FWSM software release, then the alternative is to allow traffic only from the trusted hosts. The configuration to accomplish this is as follows:

access-list sip-acl extended permit udp 10.1.1.0 255.255.255.0 host 192.168.5.4 eq sip
access-list sip-acl extended permit udp host 192.168.5.4 10.1.1.0 255.255.255.0 eq sip

class-map sip-traffic
 match access-list sip-acl
!
!
policy-map global_policy
 class inspection_default
  inspect dns maximum-length 512
  inspect ftp
  inspect h323 h225
  inspect h323 ras
  inspect rsh
  inspect rtsp
  inspect esmtp
  inspect sqlnet
  inspect skinny
  inspect sunrpc
  inspect xdmcp
  inspect netbios
  inspect tftp
 class sip-traffic
  inspect sip
!
service-policy global_policy global

In this example SIP endpoints are any host within 10.1.1.0 network (inside the trusted network) and a host with the IP address of 192.168.5.4 (outside of the trusted network). You would have to substitute these IP addresses with the ones that are used in your network.

Please note that SIP is an UDP-based protocol, so spoofing SIP messages is possible.

  1. Processing of Packets Destined to the FWSM May Cause Reload +-------------------------------------------------------------

Since this vulnerability only manifests itself when syslog message 710006 is generated, it is possible to workaround the vulnerability either by disabling generation of syslog message 710006 altogether, or by logging at a syslog level that is lower than the syslog level at which this message is generated.

By default, syslog message 710006 is generated at syslog level 7 ("debugging"), so a viable workaround is to log at level 6 or lower. This can be accomplished with the command "logging <destination> 6". If syslog message 710006 has been moved to a different logging level, then the logging level in use must be changed accordingly to prevent the message from being generated.

If logging at the "debugging" level is necessary, the vulnerability can also be eliminated by disabling this particular syslog message by using the command "no logging message 710006".

  1. Processing of Malformed HTTPS Requests May Cause Reload +---------------------------------------------------------

There are no workarounds for this vulnerability.

  1. Processing of Long HTTP Requests May Cause Reload +---------------------------------------------------

There are no workarounds for this vulnerability.

  1. Processing HTTPS Traffic May Cause a Reload +---------------------------------------------

Since this vulnerability is caused by the HTTPS server on the FWSM failing to handle certain types of HTTPS traffic, disabling the HTTPS server through the command "no http server enable" is a valid workaround if this functionality is not needed. Please note that this functionality is used by ASDM, so if configuration of the FWSM is exclusively done through ASDM disabling the HTTPS server may not be a viable workaround.

Additionally, it is possible to limit the exposure by allowing HTTPS connections only from trusted IP addresses or networks. This can be accomplished with the "http" command. For example, the following command:

        FWSM&#40;config&#41;# http 192.168.1.10 255.255.255.255 inside

will only permit HTTPS connections from the IP address 192.168.1.10.

  1. Processing of Malformed SNMP Requests May Cause a Reload +----------------------------------------------------------

This bug can only be triggered by a malformed SNMP message that comes from a device that is allowed SNMP access on the FWSM. If SNMP is not needed it can be removed through the command "no snmp-server host <interface name> <IP address of trusted device>", which will eliminate the vulnerability.

  1. Manipulation of ACL May Cause ACL Corruption +----------------------------------------------

There are no workarounds for this vulnerability. However, please note that the ACL corruption does not occur during normal operation of the device and it cannot be triggered by some type of traffic. It can only occur if an administrator makes configuration changes (and more specifically, if an administrator manipulates an ACL.) For this reason, if ACL changes are made only during a maintenance window, and the FWSM is reloaded after making those changes, there should not be any concerns with this vulnerability.

Obtaining Fixed Software

Cisco will make free software available to address this vulnerability for affected customers. This advisory will be updated as fixed software becomes available. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades.

Customers with Service Contracts +-------------------------------

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com .

Customers using Third Party Support Organizations +------------------------------------------------

Customers whose Cisco products are provided or maintained through prior or existing agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers without Service Contracts +----------------------------------

Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC contacts are as follows.

  • +1 800 553 2447 (toll free from within North America)
  • +1 408 526 7209 (toll call from anywhere in the world)
  • e-mail: tac@cisco.com

Have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

Refer to http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages.

Exploitation and Public Announcements

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

Some of these vulnerabilities where reported to Cisco by customers that experienced these issues during normal operation of their equipment. The other vulnerabilities were discovered during internal testing.

Status of this Notice: FINAL

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.

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.

Distribution

This advisory is posted on Cisco's worldwide website at :

http://www.cisco.com/warp/public/707/cisco-sa-20070214-fwsm.shtml

In addition to worldwide web posting, a text version of this notice is clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail and Usenet news recipients.

  • cust-security-announce@cisco.com
  • first-teams@first.org
  • bugtraq@securityfocus.com
  • vulnwatch@vulnwatch.org
  • cisco@spot.colorado.edu
  • cisco-nsp@puck.nether.net
  • full-disclosure@lists.grok.org.uk
  • comp.dcom.sys.cisco@newsgate.cisco.com

Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.

Revision History

+-------------------------------------------------------------+ | Revision 1.0 | 2007-Feb-14 | 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.


All contents are Copyright 1992-2007 Cisco Systems, Inc. All rights reserved.


Updated: Feb 14, 2007 Document ID: 72327


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