Summary

• 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 conduct directory traversal attacks and read sensitive files on a targeted system.

  The vulnerability is due to a lack of proper input validation of URLs in HTTP requests processed by an affected device. An attacker could exploit this vulnerability by sending a crafted HTTP request containing directory traversal character sequences to an affected device. A successful exploit could allow the attacker to view arbitrary files within the web services file system on the targeted device. As an example, this could allow an attacker to impersonate another VPN user and establish a Clientless SSL VPN or AnyConnect VPN session to the device as that user.

  The web services file system is enabled when the affected device is configured with either WebVPN or AnyConnect features. This vulnerability cannot be used to obtain access to ASA or FTD system files, underlying operating system (OS) files, or VPN user login credentials.

  Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

  Note: Cisco has become aware of the availability of public exploit code and active exploitation of the vulnerability that is described in this advisory. Cisco encourages customers with affected products to upgrade to a fixed release as soon as possible.

  This advisory is available at the following link:
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ro-path-KJuQhB86

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco products if they are running a vulnerable release of Cisco ASA Software or Cisco FTD Software with a vulnerable AnyConnect or WebVPN configuration.

  ASA Software

  In the following table, the left column lists the Cisco ASA 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 configured for one of these features, it is vulnerable.

  Cisco ASA 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 enable <interface_name>

   

  FTD Software

  In the following table, the left column lists the Cisco FTD 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 configured for one of these features, it is vulnerable.

  On devices running Cisco FTD Software, the show running-config command is available from Diagnostic CLI mode only. To enter Diagnostic CLI mode, use the system support diagnostic-cli command in the regular Firepower Threat Defense CLI.

  Cisco FTD 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 via Devices > VPN > Remote Access in the Cisco Firepower Management Center (FMC) or via Device > Remote Access VPN in Cisco Firepower Device Manager (FDM).
  2. Remote Access VPN features were first supported as of 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.

Details

• The attacker can view files within the web services file system only. The web services file system is enabled for the WebVPN and AnyConnect features outlined in the Vulnerable Products section of this advisory; therefore, this vulnerability does not apply to the ASA and FTD system files or underlying operating system (OS) files. The web services files that the attacker can view may have information such as WebVPN configuration, bookmarks, web cookies, partial web content, and HTTP URLs.

Workarounds

• There are no workarounds that address this vulnerability.

  To help detect and/or block attempts to exploit the vulnerability that is described in this advisory, customers who use the SSL Decryption feature for affected traffic on Cisco Firepower sensors can enable Snort rules 54598 through 54601, from SRU number 2020-07-22-001, by using the Cisco Firepower Management Center.

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 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

  In the following table(s), the left column lists Cisco software releases. The right column indicates whether a release is affected by the vulnerability described in this advisory and the first release that includes 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.
  9.6	9.6.4.42
  9.71	Migrate to a fixed release.
  9.8	9.8.4.20
  9.9	9.9.2.74
  9.10	9.10.1.42
  9.12	9.12.3.12
  9.13	9.13.1.10
  9.14	9.14.1.10

  1. Cisco ASA Software releases 9.5 and earlier, as well as Release 9.7, 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 6.2.2	Not vulnerable.
  6.2.2	Migrate to a fixed release.
  6.2.3	6.2.3.16
  6.3.0	Migrate to 6.4.0.9 + Hot Fix or to 6.6.0.1      or 6.3.0.5 + Hot Fix1      or 6.3.0.6 (Fall 2020)
  6.4.0	6.4.0.9 + Hot Fix1      or 6.4.0.10 (Fall 2020)
  6.5.0	Migrate to 6.6.0.1      or 6.5.0.4 + Hot Fix1      or 6.5.0.5 (Fall 2020)
  6.6.0	6.6.0.1

  1. For hot fix details please refer to the table below.

  Cisco FTD Software Hot Fix Details

  Cisco FTD Software Release	Hot Fix File Names
  6.3.0.5	Cisco_FTD_Hotfix_AV-6.3.0.6-3.sh.REL.tar           Cisco_FTD_SSP_Hotfix_AV-6.3.0.6-3.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_AV-6.3.0.6-3.sh.REL.tar
  6.4.0.9	Cisco_FTD_Hotfix_BM-6.4.0.10-2.sh.REL.tar Cisco_FTD_SSP_FP1K_Hotfix_BM-6.4.0.10-2.sh.REL.tar Cisco_FTD_SSP_FP2K_Hotfix_BM-6.4.0.10-2.sh.REL.tar Cisco_FTD_SSP_Hotfix_BM-6.4.0.10-2.sh.REL.tar
  6.5.0.4	Cisco_FTD_Hotfix_O-6.5.0.5-3.sh.REL.tar           Cisco_FTD_SSP_FP2K_Hotfix_O-6.5.0.5-3.sh.REL.tar Cisco_FTD_SSP_FP1K_Hotfix_O-6.5.0.5-3.sh.REL.tar   Cisco_FTD_SSP_Hotfix_O-6.5.0.5-3.sh.REL.tar

  To upgrade to a fixed release of Cisco FTD Software, customers can 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.

Exploitation and Public Announcements

• The Cisco Product Security Incident Response Team (PSIRT) is aware of the existence of public exploit code and active exploitation of the vulnerability that is described in this advisory.

Source

• Cisco would like to thank Mikhail Klyuchnikov of Positive Technologies and Abdulrahman Nour and Ahmed Aboul-Ela of RedForce for independently reporting this vulnerability.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ro-path-KJuQhB86

Revision History

• Version	Description	Section	Status	Date
  1.5	Clarified that VPN user login credentials are not exposed; updated availability of fixed software.	Summary, Fixed Software	Final	2020-AUG-27
  1.4	Added more detail on potential impact.	Summary	Final	2020-JUL-28
  1.3	Added mitigation details.	Workarounds	Final	2020-JUL-23
  1.2	Updated to alert about active exploitation.	Summary, Exploitation and Public Announcements	Final	2020-JUL-23
  1.1	Updated to indicate the availability of public exploit code.	Exploitation and Public Announcements	Final	2020-JUL-23
  1.0	Initial public release.	—	Final	2020-JUL-22

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