Cisco Security Advisory
Multiple Vulnerabilities in Cisco ASA 5500 Series Adaptive Security Appliances
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AV:N/AC:L/Au:N/C:C/I:N/A:N/E:F/RL:OF/RC:C
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Cisco ASA 5500 Series Adaptive Security Appliances are affected by the following vulnerabilities:
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Transparent Firewall Packet Buffer Exhaustion Vulnerability
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Skinny Client Control Protocol (SCCP) Inspection Denial of Service
Vulnerability
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Routing Information Protocol (RIP) Denial of Service
Vulnerability
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Unauthorized File System Access Vulnerability
These vulnerabilities are independent; a release that is affected by one vulnerability is not necessarily affected by the others.
Cisco has released software updates that address these vulnerabilities.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110223-asa.
Note: The Cisco Firewall Services Module (FWSM) is affected by one of these vulnerabilities. A separate Cisco Security Advisory has been published to disclose the vulnerability that affects the Cisco FWSM. That advisory is available at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110223-fwsm.
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Transparent Firewall Packet Buffer Exhaustion Vulnerability
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Cisco ASA 5500 Series Adaptive Security Appliances are affected by multiple vulnerabilities. Affected versions of Cisco ASA Software vary depending on the specific vulnerability.
Vulnerable Products
For specific version information, refer to the Software Versions and Fixes section of this advisory.
Transparent Firewall Packet Buffer Exhaustion Vulnerability
A packet buffer exhaustion vulnerability affects multiple versions of Cisco ASA Software when a security appliance is configured to operate in the transparent firewall mode. Transparent firewall mode is enabled on the appliance if the command firewall transparent is present in the configuration. The default firewall mode is routed, not transparent. The show firewall command can also be used to determine the firewall operation mode:
ciscoasa# show firewall Firewall mode: Transparent
SCCP Inspection Denial of Service Vulnerability
A denial of service vulnerability affects the SCCP inspection feature of Cisco ASA 5500 Series Adaptive Security Appliances.
Administrators can determine if SCCP inspection is enabled by issuing the show service-policy | include skinny command and confirming that output, such as what is displayed in the following example, is returned.
ciscoasa# show service-policy | include skinny Inspect: skinny, packet 0, drop 0, reset-drop 0Alternatively, a device that has SCCP inspection enabled has a configuration similar to the following:
class-map inspection_default match default-inspection-traffic ! policy-map global_policy class inspection_default ... inspect skinny ... ! service-policy global_policy global
Note: The service policy could also be applied to a specific interface instead of globally, which is displayed in the previous example.
SCCP inspection is enabled by default.
RIP Denial of Service Vulnerability
A denial of service vulnerability affects the RIP implementation in Cisco ASA 5500 Series Adaptive Security Appliances when both RIP and the Cisco Phone Proxy feature are enabled on the same device. The following example displays an affected configuration (Cisco ASA Software version 8.0 and 8.1):
router rip ... ! phone-proxy
media-termination address ... Or (Cisco ASA Software version 8.2 and later):
router rip ... ! media-termination
address ! A security appliance is vulnerable if it is processing RIP messages (router rip) and if a global media termination address is configured for the Cisco Phone Proxy feature (refer to previous example). Note that Cisco ASA Software versions 8.0 and 8.1 only allow a global media termination address. However, in Cisco ASA Software version 8.2 and later, it is possible to tie a media termination address to an interface. This configuration, which is accomplished by issuing the command address
interface in media termination configuration mode, is not affected.Neither RIP nor the Cisco Phone Proxy feature is enabled by default.
Unauthorized File System Access Vulnerability
An unauthorized file system access vulnerability affects Cisco ASA 5500 Series Adaptive Security Appliances when a security appliance is configured as a local Certificate Authority (CA). An affected configuration consists of the following minimum commands:
crypto ca trustpoint
keypair crl configure crypto ca server crypto ca certificate chain certificate ca 01 ... ! http server enable The local CA server is not enabled by default.
Cisco PIX 500 Series Security Appliance Vulnerability Status
Cisco PIX 500 Series Security Appliances are affected by the Transparent Firewall Packet Buffer Exhaustion Vulnerability and the SCCP Inspection Denial of Service Vulnerability.
Because Cisco PIX 500 Series Security Appliances reached the end of software maintenance releases milestone on July 28, 2009, no further software releases will be available. Cisco PIX 500 Series Security Appliance customers are encouraged to migrate to Cisco ASA 5500 Series Adaptive Security Appliances or to implement any applicable workarounds that are listed in the Workarounds section of this advisory. Fixed software is available for Cisco ASA 5500 Series Adaptive Security Appliances only. For more information, refer to the End of Life announcement at http://www.cisco.com/en/US/prod/collateral/vpndevc/ps5708/ps5709/ps2030/end_of_life_notice_cisco_pix_525_sec_app.html.
How to Determine Software Versions
To determine whether a vulnerable version of Cisco ASA Software is running on an appliance, administrators can issue the show version command. The following example shows a Cisco ASA 5500 Series Adaptive Security Appliance that is running software version 8.3(1):
ASA#show version | include Version Cisco Adaptive Security Appliance Software Version 8.3(1) Device Manager Version 6.3(1)
Customers who use Cisco Adaptive Security Device Manager (ASDM) to manage devices can locate the software version in the table that is displayed in the login window or upper-left corner of the Cisco ASDM window.
Products Confirmed Not Vulnerable
With the exception of Cisco PIX 500 Series Security Appliances and the Cisco Firewall Services Module, no other Cisco products are currently known to be affected by these vulnerabilities.
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The Cisco ASA 5500 Series Adaptive Security Appliance is a modular platform that provides security and VPN services. It offers firewall, intrusion prevention system (IPS), anti-X, and virtual private network (VPN) services.
Cisco ASA 5500 Series Adaptive Security Appliances are affected by the following vulnerabilities:
Transparent Firewall Packet Buffer Exhaustion Vulnerability
A Cisco ASA 5500 Series Adaptive Security Appliance that is configured for transparent firewall mode is affected by a packet buffer exhaustion vulnerability that could cause an appliance to stop forwarding traffic once all packet buffers are depleted. The number of available packet buffers may decrease when a security appliance receives IPv6 traffic and is not configured for IPv6 operation. IPv6 transit traffic does not cause a problem.
Administrators can check packet buffer utilization by issuing the command show blocks and inspecting the output for the number of available 1,550-byte blocks. If the number of blocks is zero (indicated by 0 in the CNT column), then the security appliance may be experiencing this issue. For example:
ciscoasa# show blocks SIZE MAX LOW CNT 0 400 360 400 4 200 199 199 80 400 358 400 256 1412 1381 1412 1550 6274 0 0 ...This vulnerability is documented in Cisco bug ID CSCtj04707 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0393.
SCCP Inspection Denial of Service Vulnerability
Cisco ASA 5500 Series Adaptive Security Appliances are affected by a vulnerability that could cause the appliance to reload when it processes a malformed SCCP message. Appliances are only vulnerable if SCCP inspection is enabled.
Only transit traffic can trigger this vulnerability; traffic that is destined to the appliance will not trigger the vulnerability.
This vulnerability is documented in Cisco bug ID CSCtg69457 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0394.
RIP Denial of Service Vulnerability
Cisco ASA 5500 Series Adaptive Security Appliances are affected by a vulnerability that could cause the appliance to reload when it processes valid RIP updates. Appliances are vulnerable only if both RIP and the Cisco Phone Proxy feature are enabled.
Note: the affected configuration requires that a global media termination address is configured, which is the only possible configuration option in Cisco ASA Software versions 8.0 and 8.1. However, it is possible to tie a media termination address to an interface in Cisco ASA Software version 8.2 and later. This configuration is not vulnerable.
This vulnerability is documented in Cisco bug ID CSCtg66583 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0395.
Unauthorized File System Access Vulnerability
Cisco ASA 5500 Series Adaptive Security Appliances are affected by a vulnerability that could allow unauthorized users to access a file system (flash:, disk0:, disk1:, etc. but not system:) when the security appliance is configured as a local CA server. No authentication is required. File systems could contain sensitive information, such as backup device configurations (which may contain passwords or shared secrets), Cisco ASA Software images, or digital certificates.
This vulnerability is documented in Cisco bug ID CSCtk12352 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-0396.
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This Cisco Security Advisory describes multiple distinct vulnerabilities. These vulnerabilities and their respective workarounds are independent of each other.
Transparent Firewall Packet Buffer Exhaustion Vulnerability
There are no workarounds for this vulnerability.
SCCP Inspection Denial of Service Vulnerability
Administrators can mitigate this vulnerability by disabling SCCP inspection if it is not required. Administrators can disable SCCP inspection by issuing the no inspect skinny command in class configuration submode in the policy map configuration.
RIP Denial of Service Vulnerability
There are no workarounds for Cisco ASA Software version 8.0 and 8.1. On Cisco ASA Software version 8.2 and later, administrators can configure a non-global media termination address by specifying a termination address that will be tied to a specific interface. For example:
router rip ... ! media-termination
address interface ! Unauthorized File System Access Vulnerability
There are no workarounds for this vulnerability.
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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.
Vulnerability
Major Release
First Fixed Release
Transparent Firewall Packet Buffer Exhaustion Vulnerability (CSCtj04707)
7.0
7.0(8.12); available late February 2011
7.1
Vulnerable; migrate to 7.2(5.2)
7.2
7.2(5.2)
8.0
8.0(5.21)
8.1
8.1(2.49); available early March 2011
8.2
8.2(3.6)
8.3
8.3(2.7)
8.4
Not vulnerable
SCCP Inspection Denial of Service Vulnerability (CSCtg69457)
7.0
7.0(8.11)
7.1
Vulnerable; migrate to 7.2(5.1)
7.2
7.2(5.1)
8.0
8.0(5.19)
8.1
8.1(2.47)
8.2
8.2(2.19)
8.3
8.3(1.8)
8.4
Not vulnerable
RIP Denial of Service Vulnerability (CSCtg66583)
7.0
Not vulnerable
7.1
Not vulnerable
7.2
Not vulnerable
8.0
8.0(5.20)
8.1
8.1(2.48)
8.2
8.2(3)
8.3
8.3(2.1)
8.4
Not vulnerable
Unauthorized File System Access Vulnerability (CSCtk12352)
7.0
Not vulnerable
7.1
Not vulnerable
7.2
Not vulnerable
8.0
8.0(5.23)
8.1
8.1(2.49); available early March 2011
8.2
8.2(4.1)
8.3
8.3(2.13)
8.4
Not vulnerable
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
7.0
7.0(8.12); available late February 2011
7.1
Migrate to 7.2(5.2)
7.2
7.2(5.2)
8.0
8.0(5.23)
8.1
8.1(2.49); available early March 2011
8.2
8.2(4.1)
8.3
8.3(2.13)
8.4
8.4(1)
Software Download
Cisco ASA Software can be downloaded from the Software Center on Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.html and navigating to Products > Security > Firewall > Firewall Appliances > Cisco ASA 5500 Series Adaptive Security Appliances >
> Adaptive Security Appliance (ASA) Software.
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The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory.
The Transparent Firewall Packet Buffer Exhaustion Vulnerability, SCCP Inspection Denial of Service Vulnerability, and RIP Denial of Service Vulnerability were found during internal testing.
The Unauthorized File System Access Vulnerability was discovered during the resolution of customer support cases.
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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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