Cisco Email Security Appliance and Cisco Secure Email and Web Manager External Authentication Bypass Vulnerability

Summary

• A vulnerability in the external authentication functionality of Cisco Secure Email and Web Manager, formerly known as Cisco Security Management Appliance (SMA), and Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass authentication and log in to the web management interface of an affected device.

  This vulnerability is due to improper authentication checks when an affected device uses Lightweight Directory Access Protocol (LDAP) for external authentication. An attacker could exploit this vulnerability by entering a specific input on the login page of the affected device. A successful exploit could allow the attacker to gain unauthorized access to the web-based management interface of the affected device.

  Cisco has released software updates that address this vulnerability. There are workarounds that address this vulnerability.

  This advisory is available at the following link:
  https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-esa-auth-bypass-66kEcxQD

Affected Products

• Vulnerable Products

  This vulnerability affects Cisco ESA and Cisco Secure Email and Web Manager, both virtual and hardware appliances, if they are running a vulnerable release of Cisco AsyncOS Software and the following are true:

  • The devices are configured to use external authentication.
  • The devices use LDAP as authentication protocol.

  Note: External authentication is disabled by default.

  Determine Whether External Authentication is Enabled

  To determine whether external authentication is enabled on a device, do the following:

  1. Log in to the web-based management interface of Cisco Secure Email and Web Manager or Cisco ESA.
  2. Navigate to System Administration > Users.
  3. Go to the External Authentication section.

  If the Enable External Authentication check box is checked in green, external authentication is enabled.

  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 also confirmed that this vulnerability does not affect Cisco Secure Web Appliance, formerly known as Cisco Web Security Appliance (WSA).

Workarounds

• There is a workaround that addresses this vulnerability. Administrators can disable the anonymous binds on the external authentication server.

  Note: This action must be performed on the server that handles external authentication. Administrators should work with their networking teams to implement this workaround. The external authentication feature provided by the Cisco Secure devices should not be hindered by this workaround.

  While this workaround has been deployed and was proven successful in a test environment, customers should determine the applicability and effectiveness in their own environment and under their own use conditions. Customers should be aware that any workaround or mitigation that is implemented may negatively impact the functionality or performance of their network based on intrinsic customer deployment scenarios and limitations. Customers should not deploy any workarounds or mitigations before first evaluating the applicability to their own environment and any impact to such environment.

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 that is described in this advisory and the first release that includes the fix for this vulnerability. Customers are advised to upgrade to an appropriate fixed software release as indicated in this section.

  Secure Email and Web Manager: CSCvx88026

  Cisco AsyncOS Release	First Fixed Release
  111 and earlier	Migrate to fixed release.
  12	Migrate to fixed release.
  12.8	Migrate to fixed release.
  13.0	13.0.0-277
  13.6	13.6.2-090
  13.8	13.8.1-090
  14.0	14.0.0-418
  14.1	14.1.0-250

  1. Cisco AsyncOS Software releases earlier than Release 11 have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.

  Email Security Appliance: CSCvy13453

  Cisco AsyncOS Release	First Fixed Release
  Earlier than 111	Migrate to fixed release.
  11	Migrate to fixed release.
  12	Migrate to fixed release.
  13	Migrate to fixed release.
  14	14.0.1-033

  1. Cisco AsyncOS Software releases earlier than Release 11 have reached end of software maintenance. Customers are advised to migrate to a supported release that includes the fix for this vulnerability.

  Cisco Cloud Email Security (CES) includes Cisco ESA and Cisco Secure Email and Web Manager devices as part of the service solution. Cisco provides regular maintenance of the products included in this solution. Customers can also request a software upgrade by contacting Cisco CES support.

  The Cisco Product Security Incident Response Team (PSIRT) validates only the affected and fixed release information that is documented in this advisory.

Exploitation and Public Announcements

• The Cisco 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sma-esa-auth-bypass-66kEcxQD

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	-	Final	2022-JUN-15

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