Cisco Security Advisory
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CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N/E:X/RL:X/RC:X
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Update from October 22nd, 2020: Cisco has become aware of a new Cisco Adaptive Security Appliance vulnerability that could affect the fixed releases recommended for code trains 9.13 and 9.14 in the Fixed Software section of this advisory. See the Cisco Adaptive Security Appliance Software SSL/TLS Denial of Service Vulnerability for additional information.
A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass a configured access rule and access parts of the WebVPN portal that are supposed to be blocked.
The vulnerability is due to insufficient validation of URLs when portal access rules are configured. An attacker could exploit this vulnerability by accessing certain URLs on the affected device.
Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-rule-bypass-P73ABNWQ
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Vulnerable Products
At the time of publication, this vulnerability affected Cisco products if they were running a vulnerable release of Cisco ASA Software or FTD Software with a vulnerable AnyConnect or WebVPN configuration and had a portal access rule configured.
For information about which Cisco software releases were vulnerable, see the Fixed Software section of this advisory. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
Determine Whether a Portal Access Rule Is Configured
To verify whether a portal access rule is configured, use the show running-config webvpn | include portal-access-rule command. If that command returns output, the device is vulnerable. Empty output indicates that the device is not vulnerable.
Determine Whether a Vulnerable AnyConnect or WebVPN Configuration Is Present
Cisco ASA Software
In the following table, the left column lists the Cisco ASA Software features that are vulnerable. The right column indicates the basic configuration for the feature from the show running-config CLI command. If the device is running a vulnerable release and is configured for one of these features, it is vulnerable.
Cisco ASA Software Feature Vulnerable Configuration AnyConnect IKEv2 Remote Access (with client services) crypto ikev2 enable <interface_name> client-services port <port #>
AnyConnect SSL VPN webvpn
enable <interface_name>Clientless SSL VPN webvpn
webvpn
enable <interface_name>Cisco FTD Software
In the following table, the left column lists the Cisco FTD Software features that are vulnerable. The right column indicates the basic configuration for the feature from the show running-config CLI command. If the device is running a vulnerable release and is configured for one of these features, it is vulnerable.
Cisco FTD Software Feature Vulnerable Configuration AnyConnect IKEv2 Remote Access (with client services)1,2 crypto ikev2 enable <interface_name> client-services port <port #>
AnyConnect SSL VPN1,2 webvpn
enable <interface_name>1. Remote Access VPN features are enabled by using Devices > VPN > Remote Access in Cisco Firepower Management Center (FMC) or by using Device > Remote Access VPN in Cisco Firepower Device Manager (FDM).
2. Remote Access VPN features are first supported in Cisco FTD Software Release 6.2.2.Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect Cisco Firepower Management Center (FMC) Software.
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There are no workarounds that address this vulnerability.
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When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories page, 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.
Fixed Releases
At the time of publication, the release information in the following table(s) was accurate. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.
The left column lists Cisco software releases, and the right column indicates whether a release was affected by the vulnerability described in this advisory and which release included the fix for this vulnerability.
Cisco ASA Software
Cisco ASA Software Release First Fixed Release for This Vulnerability Earlier than 9.61 Migrate to a fixed release. 9.61 9.6.4.45 9.71 Migrate to a fixed release. 9.8 9.8.4.26 9.9 9.9.2.80 9.10 9.10.1.44 9.12 9.12.4.4 9.13 9.13.1.13 9.14 9.14.1.19 1. Cisco ASA Software releases 9.7 and earlier have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.
Cisco FTD Software
Cisco FTD Software Release First Fixed Release for This Vulnerability Earlier than 6.2.21 Migrate to a fixed release. 6.2.2 Migrate to a fixed release. 6.2.3 Migrate to a fixed release. 6.3.0 6.3.0.6 (future release) 6.4.0 6.4.0.10 6.5.0 6.5.0.5 (future release) 6.6.0 6.6.1 1. Cisco FMC and FTD Software releases 6.0.1 and earlier, as well as releases 6.2.0 and 6.2.1, have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.
To upgrade to a fixed release of Cisco FTD Software, do one of the following:
- For devices that are managed by using Cisco Firepower Management Center (FMC), use the FMC interface to install the upgrade. After installation is complete, reapply the access control policy.
- For devices that are managed by using Cisco Firepower Device Manager (FDM), use the FDM interface to install the upgrade. After installation is complete, reapply the access control policy.
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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.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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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 LessVersion Description Section Status Date 2.0 Updated the Summary section to provide information on a new vulnerability affecting fixed release recommendations for code trains 9.13 and 9.14. Summary Final 2020-OCT-22 1.0 Initial public release. — Final 2020-OCT-21
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