Summary

• 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.

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  A vulnerability in the Clientless SSL VPN (WebVPN) of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to inject arbitrary HTTP headers in the responses of the affected system.

  The vulnerability is due to improper input sanitization. An attacker could exploit this vulnerability by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to conduct a CRLF injection attack, adding arbitrary HTTP headers in the responses of the system and redirecting the user to arbitrary websites.

  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-asa-ftd-crlf-inj-BX9uRwSn

Affected Products

• Vulnerable Products

  At the time of publication, this vulnerability affected Cisco products running Cisco ASA Software or FTD Software when configured for AnyConnect/WebVPN and the Load Balancing service was enabled.

  For information about which Cisco ASA Software and FTD 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 If WebVPN Is Enabled

  To determine if the WebVPN service is enabled on a device, use the show running-config webvpn privileged EXEC command and refer to the output of the command. The following example shows the output of the command for a device that has the WebVPN service enabled:

  ciscoasa# show running-config webvpn
  .
  .
  .
  webvpn
  enable interface_name
  .
  .
  .

  To view AnyConnect-related configuration, use the show webvpn anyconnect command.

  Determine If Load Balancing Is Enabled

  To determine if the Load Balancing service is enabled on a device, see Viewing VPN Load Balancing Information.

  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.

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• 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	9.6.4.35
  9.71	9.8.4.20
  9.8	9.8.4.20
  9.9	9.9.2.80
  9.10	9.10.1.43
  9.12	9.12.3.9
  9.13	9.13.1.10
  9.14	9.14.1.10

  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 6.3.01	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.

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.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-crlf-inj-BX9uRwSn

Revision History

• Version	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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