CVE-2022-20868 in ESA
Summary
by MITRE • 11/04/2022
A vulnerability in the web-based management interface of Cisco Email Security Appliance, Cisco Secure Email and Web Manager and Cisco Secure Web Appliance could allow an authenticated, remote attacker to elevate privileges on an affected system. The attacker needs valid credentials to exploit this vulnerability. This vulnerability is due to the use of a hardcoded value to encrypt a token used for certain APIs calls . An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP request. A successful exploit could allow the attacker to impersonate another valid user and execute commands with the privileges of that user account.
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Analysis
by VulDB Data Team • 12/03/2022
The vulnerability identified as CVE-2022-20868 represents a critical privilege escalation flaw within Cisco's email and web security appliance ecosystem. This weakness affects the web-based management interfaces of Cisco Email Security Appliance, Cisco Secure Email and Web Manager, and Cisco Secure Web Appliance products. The vulnerability stems from a fundamental cryptographic design flaw where the system employs a hardcoded encryption value for token generation used in application programming interface communications. This hardcoded approach violates established security principles and creates a predictable encryption mechanism that can be exploited by malicious actors. The vulnerability requires an attacker to possess valid authentication credentials to exploit, but once accessed, it provides a pathway for unauthorized privilege elevation.
The technical exploitation of this vulnerability occurs through a specific attack vector involving crafted HTTP requests sent to the affected management interface. When an authenticated attacker successfully crafts and submits these requests, the hardcoded encryption value allows the attacker to manipulate the token generation process. This manipulation enables the attacker to impersonate legitimate user accounts within the system, effectively bypassing normal authentication and authorization controls. The underlying cryptographic weakness manifests as a failure to implement proper randomization or unique encryption keys for token generation, creating a scenario where the same encryption value is reused across multiple sessions and API calls. This flaw directly maps to CWE-327, which addresses the use of insecure cryptographic algorithms and hardcoded cryptographic values that undermine the security of authentication mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass potential full system compromise and unauthorized administrative access. An attacker who successfully exploits this vulnerability can execute commands with the privileges of any user account within the system, potentially including administrative accounts with elevated permissions. This capability allows for comprehensive system infiltration, data exfiltration, and modification of security policies. The attack surface is particularly concerning given that these appliances serve as critical security gateways for email and web traffic filtering, making successful exploitation a severe threat to organizational security posture. The vulnerability's impact aligns with ATT&CK technique T1078.004, which covers valid accounts used for unauthorized access, as the attacker leverages legitimate user credentials to escalate privileges rather than bypassing authentication entirely.
Mitigation strategies for this vulnerability require immediate implementation of Cisco's official security patches and updates provided through their vulnerability management channels. Organizations should also implement network segmentation to limit access to these management interfaces, enforce strict access controls through role-based permissions, and monitor for unusual API activity patterns that might indicate exploitation attempts. Additional defensive measures include implementing multi-factor authentication for management interfaces, regularly rotating administrative credentials, and conducting comprehensive vulnerability assessments of the affected appliance configurations. The remediation process should also involve reviewing and strengthening cryptographic implementations across all management interfaces to ensure that encryption keys and values are properly randomized and not hardcoded. Network monitoring solutions should be configured to detect and alert on anomalous HTTP request patterns that could indicate exploitation attempts targeting this specific vulnerability, as the attack requires only authenticated access but can result in significant privilege escalation and system compromise.