Cisco Email Security Appliance Allows for Authentication Bypass

Fortify Security Team
Jun 16, 2022

A vulnerability in Cisco Email Security Appliance, Cisco Secure Email & Web Manager could Allow for an authentication bypass under specific conditions. Exploitation of this vulnerability could allow for an unauthenticated attacker to gain unauthorized access to the web-based management interface of the affected device.

THREAT INTELLIGENCE: There are currently no reports of these vulnerabilities being exploited in the wild.

SYSTEMS AFFECTED:

  • Cisco Email Security Appliance, Cisco Secure Email & Web manager running a vulnerable release of Cisco AsyncOS software. Please review the referenced Cisco advisory for a detail list of affected software versions.

RISK:
Government:

  • Large and medium government entities: High
  • Small government entities: Medium

Businesses:

  • Large and medium business entities: High
  • Small business entities: Medium

Home users: Low

TECHNICAL SUMMARY:
A vulnerability in Cisco Email Security Appliance, Cisco Secure Email & Web Manager could Allow for an authentication bypass under specific conditions:

  • The affected device enable the use of external authentication
  • The affected device is utilizing LDAP as its authentication protocol

TacticInitial Access (TA0001):
TechniqueExploit Public-Facing Application (T1190):

  • Improper authentication checks when an affected device uses Lightweight Directory Access Protocol (LDAP) for external authentication. (CVE-2022-20798)

Exploitation of this vulnerability could allow for an unauthenticated attacker to gain unauthorized access to the web-based management interface of the affected device.

RECOMMENDATIONS:
We recommend the following actions be taken:

  • Apply appropriate updates provided by Cisco to vulnerable systems immediately after appropriate testing. (M1051: Update Software, M1042: Disable or Remove Feature or Program)
    • Safeguard 7.1: Establish and Maintain a Vulnerability Management Process: Establish and maintain a documented vulnerability management process for enterprise assets. Review and update documentation annually, or when significant enterprise changes occur that could impact this Safeguard.
    • Safeguard 7.4: Perform Automated Application Patch Management: Perform application updates on enterprise assets through automated patch management on a monthly, or more frequent, basis.
  • Apply the Principle of Least Privilege to all systems and services. Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack. (M1026: Privileged Account Management)
    • Safeguard 4.7: Manage Default Accounts on Enterprise Assets and Software: Manage default accounts on enterprise assets and software, such as root, administrator, and other pre-configured vendor accounts. Example implementations can include: disabling default accounts or making them unusable.
    • Safeguard 5.4: Restrict Administrator Privileges to Dedicated Administrator Accounts: Restrict administrator privileges to dedicated administrator accounts on enterprise assets. Conduct general computing activities, such as internet browsing, email, and productivity suite use, from the user’s primary, non-privileged account.
  • Use capabilities to prevent suspicious behavior patterns from occurring on endpoint systems. This could include suspicious process, file, API call, etc. behavior. (M1040 : Behavior Prevention on Endpoint)
    • Safeguard 13.2 : Deploy a Host-Based Intrusion Detection Solution: Deploy a host-based intrusion detection solution on enterprise assets, where appropriate and/or supported.

Safeguard 13.7 : Deploy a Host-Based Intrusion Prevention Solution: Deploy a host-based intrusion prevention solution on enterprise assets, where appropriate and/or supported. Example implementations include use of an Endpoint Detection and Response (EDR) client or host-based IPS agent.

REFERENCES:

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

CVE: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-20798

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