Cisco Security Advisory Cisco Adaptive Security Appliance TLS Denial of Service Vulnerability High Advisory ID: cisco-sa-20180418-asa3 First Published: 2018 April 18 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCve18902 CSCve34335 CSCve38446 CVE-2018-0231 CWE-20 CVSS Score: Base 8.6 Click Icon to Copy Verbose Score

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X CVE-2018-0231 CWE-20 Download CVRF Download PDF Email Summary



The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious TLS message to an interface enabled for Secure Layer Socket (SSL) services on an affected device. Messages using SSL Version 3 (SSLv3) or SSL Version 2 (SSLv2) cannot be be used to exploit this vulnerability. An exploit could allow the attacker to cause a buffer underflow, triggering a crash on an 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-asa3 A vulnerability in the Transport Layer Security (TLS) library of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of the affected device, resulting in a denial of service (DoS) condition.The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a malicious TLS message to an interface enabled for Secure Layer Socket (SSL) services on an affected device. Messages using SSL Version 3 (SSLv3) or SSL Version 2 (SSLv2) cannot be be used to exploit this vulnerability. An exploit could allow the attacker to cause a buffer underflow, triggering a crash on an 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: Affected Products Vulnerable Products

Adaptive Security Virtual Appliance (ASAv) Firepower Threat Defense Virtual (FTDv) Firepower 2100 Series Security Appliance ASA Software Cisco ASA Software is only vulnerable if running software version 9.2 or later.



In the following table, the left column lists the vulnerable Cisco ASA features. The right column indicates the vulnerable configuration from the CLI command show running-config , if it can be determined.



Feature Vulnerable Configuration

Adaptive Security Device Manager (ASDM) 1

http server enable <port>

http <remote_ip_address> <remote_subnet_mask> <interface_name> AnyConnect SSL VPN webvpn

enable <interface_name> Cisco Security Manager 2 http server enable <port>

http <remote_ip_address> <remote_subnet_mask> <interface_name> Clientless SSL VPN webvpn

enable <interface_name> Mobile User Security (MUS) webvpn

mus password <password>

mus server enable port <port #>

mus <address> <mask> <interface_name> Security Assertion Markup Language (SAML) Single Sign-On (SSO) 3 N/A This vulnerability affects Cisco ASA Software and Cisco FTD Software that is running on the following Cisco products:Cisco ASA Software is only vulnerable if running software version 9.2 or later.In the following table, the left column lists the vulnerable Cisco ASA features. The right column indicates the vulnerable configuration from the CLI command, if it can be determined. 1 ASDM is vulnerable only from an IP address in the configured http command range.

2 Cisco Security Manager is vulnerable only from an IP address in the configured http command range.

3 SAML SSO is first supported as of software release 9.6. Determining the Cisco ASA Software Release To determine whether a vulnerable version of Cisco ASA Software is running on a device, administrators can use the show version command in the CLI. The following example shows the output of the command for a device that is running Cisco ASA Software Release 9.7(1)4 :

ciscoasa# show version | include Version Cisco Adaptive Security Appliance Software Version 9.7(1)4 Firepower Extensible Operating System Version 2.1(1.66) Baseboard Management Controller (revision 0x1) Firmware Version: 2.4 Customers who use Cisco Adaptive Security Device Manager (ASDM) to manage devices can locate the software release in the table that appears in the login window or the upper-left corner of the Cisco ASDM window. FTD Software The FTD Software is only vulnerable if running software versions 6.0, 6.0.1, 6.1.0, 6.2.1, or 6.2.2 prior to their respective first fixed releases.



In the following table, the left column lists the vulnerable Cisco FTD features. The right column indicates the vulnerable configuration from the CLI command show running-config , if it can be determined.



Feature Vulnerable Configuration

HTTP Service enabled 1 http server enable <port #>

http <remote_ip_address> <remote_subnet_mask> <interface_name> AnyConnect SSL VPN 2,3 webvpn

enable <interface_name> To determine whether a vulnerable version of Cisco ASA Software is running on a device, administrators can use thecommand in the CLI. The following example shows the output of the command for a device that is running Cisco ASA Software ReleaseCustomers who use Cisco Adaptive Security Device Manager (ASDM) to manage devices can locate the software release in the table that appears in the login window or the upper-left corner of the Cisco ASDM window.The FTD Software is only vulnerable if running software versions 6.0, 6.0.1, 6.1.0, 6.2.1, or 6.2.2 prior to their respective first fixed releases.In the following table, the left column lists the vulnerable Cisco FTD features. The right column indicates the vulnerable configuration from the CLI command, if it can be determined. 1 The HTTP feature is enabled via the Firepower Threat Defense Platform Settings > HTTP configuration page on the Firepower Management Console (FMC).

2 Remote Access VPN features are enabled via the Devices > VPN > Remote Access configuration page on the FMC or via the Device > Remote Access VPN configuration page on the Firepower Device Manager (FDM).

3 Remote Access VPN features are first supported as of software release 6.2.1. Determining the Cisco FTD Software Release To determine which Cisco FTD Software release is running on a device, administrators can log in to the device and use the show version command in the CLI. The following example shows the output of the command for a device that is running Cisco FTD Software Release 6.2.2: > show version ------------------[ ftd ]-----------------------

Model : Cisco Firepower 2130 Threat Defense (77) Version 6.2.2 (Build 81)

UUID : 0cd3595a-7efa-11e7-aaa1-ee3989c8bf25

Rules update version : 2017-12-20-001-vrt

VDB version : 290

---------------------------------------------------- Products Confirmed Not Vulnerable No other Cisco products are currently known to be affected by this vulnerability.

Workarounds There are no workarounds that address this vulnerability. Fixed Software Cisco has released free software updates that address the vulnerability described in this advisory. Customers may only install and expect support for software versions and feature sets for which they have purchased a license. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license:

https://www.cisco.com/c/en/us/products/end-user-license-agreement.html Additionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades. When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts 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. Customers Without Service Contracts 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 TAC:

https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html 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. Fixed Releases Customers should upgrade to an appropriate release as indicated in the table(s) in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:

cisco-sa-20180418-asa1: Cisco Adaptive Security Appliance SSL Certificate Bypass Vulnerability cisco-sa-20180418-asa2: Cisco Adaptive Security Appliance Flow Creation Denial of Service Vulnerability cisco-sa-20180418-asa3: Cisco Adaptive Security Appliance TLS Denial of Service Vulnerability cisco-sa-20180418-asaanyconnect: Cisco ASA Software, FTD Software, and AnyConnect Secure Mobility Client SAML Authentication Session Fixation Vulnerability cisco-sa-20180418-asa_inspect: Cisco Adaptive Security Appliance Application Layer Protocol Inspection Denial of Service Vulnerability In the following table(s), the left column lists major releases of Cisco software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in this collection of advisories and the current recommended release for those vulnerabilities. ASA Software Cisco ASA Major Release First Fixed Release for This Vulnerability

Recommended Fixed Release for All the Vulnerabilities Described in this Collection of Advisories

Prior to 9.1 1

Not vulnerable

9.1.7.20 9.1 Not vulnerable 9.1.7.20 9.2 9.2.4.27 9.2.4.27 9.3 1 Migrate to 9.4.4.13

9.4.4.14 9.4 9.4.4.13 9.4.4.14 9.5 1 Migrate to 9.6.3.20

9.6.4.6 9.6 9.6.3.20 9.6.4.6 9.7 9.7.1.16 9.7.1.24 9.8 9.8.2.14 9.8.2.28 9.9 Not vulnerable

9.9.2.1

1 Cisco ASA Software releases prior to 9.1 and ASA releases 9.3 and 9.5 have reached End of Software Maintenance. Customers should migrate to a supported release.



The software is available for download from Cisco Products > Security > Firewalls > Adaptive Security Appliances (ASA) > ASA 5500-X Series Firewalls where there is a list of ASA hardware platforms. The majority of these software releases are listed under Interim. FTD Software Cisco FTD Major Release

First Fixed Release for This Vulnerability

Recommended Fixed Release for All the Vulnerabilities Described in this Collection of Advisories

6.0 Migrate to 6.1.0.6

Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform)



Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300) 6.0.1 Migrate to 6.1.0.6

Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform)



Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300) 6.1.0 6.1.0.6 Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platform)



Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (All FTD hardware platforms except 41xx and 9300) 6.2.0 Not vulnerable 1

6.2.0.5 6.2.1 Migrate to 6.2.2.1 Cisco_FTD_SSP_Hotfix_BD-6.2.2.3-4.sh.REL.tar (41xx and 9300 FTD hardware platforms)



Cisco_FTD_SSP_FP2K_Hotfix_BD-6.2.2.3-4.sh.REL.tar (21xx FTD hardware platform)



Cisco_FTD_Hotfix_BD-6.2.2.3-4.sh.REL.tar (All other FTD hardware platforms) 6.2.2 6.2.2.1 Cisco_FTD_SSP_Hotfix_BD-6.2.2.3-4.sh.REL.tar (41xx and 9300 FTD hardware platforms)



Cisco_FTD_SSP_FP2K_Hotfix_BD-6.2.2.3-4.sh.REL.tar (21xx FTD hardware platform)



Cisco_FTD_Hotfix_BD-6.2.2.3-4.sh.REL.tar (All other FTD hardware platforms) 6.2.3 Not vulnerable

Cisco_FTD_SSP_Hotfix_A-6.2.3.1-10.sh.REL.tar (41xx and 9300 FTD hardware platforms)



Cisco_FTD_SSP_FP2K_Hotfix_A-6.2.3.1-10.sh.REL.tar (21xx FTD hardware platform)



Cisco_FTD_Hotfix_A-6.2.3.1-10.sh.REL.tar (All other FTD hardware platforms)

1 Cisco FTD Software release 6.2.0 introduced a new HTTP server and thus the attack vector via the HTTP Service no longer applies.



The software is available for download from Cisco Products > Security > Firewalls> Next-Generation Firewalls (NGFW) where there is a list of possible FTD hardware platforms. Customers should upgrade to an appropriate release as indicated in the table(s) in this section. To help ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:In the following table(s), the left column lists major releases of Cisco software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in this collection of advisories and the current recommended release for those vulnerabilities.Cisco ASA Software releases prior to 9.1 and ASA releases 9.3 and 9.5 have reached End of Software Maintenance. Customers should migrate to a supported release.The software is available for download from Cisco Software Center by navigating towhere there is a list of ASA hardware platforms. The majority of these software releases are listed under Interim.Cisco FTD Software release 6.2.0 introduced a new HTTP server and thus the attack vector via the HTTP Service no longer applies.The software is available for download from Cisco Software Center by navigating towhere there is a list of possible FTD hardware platforms.

Exploitation and Public Announcements 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. Source This vulnerability was found during the resolution of a Cisco TAC support case. Cisco Security Vulnerability Policy 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. Subscribe URL https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180418-asa3 Revision History Version Description Section Status Date 1.0 Initial public release. — Final 2018-April-18 Show Less Legal Disclaimer 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 standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products. Cisco Security Vulnerability Policy 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. Subscribe