CVE-2017-8055 in Firebox
Summary
by MITRE
WatchGuard Fireware allows user enumeration, e.g., in the Firebox XML-RPC login handler. A login request that contains a blank password sent to the XML-RPC agent in Fireware v11.12.1 and earlier returns different responses for valid and invalid usernames. An attacker could exploit this vulnerability to enumerate valid usernames on an affected Firebox.
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Analysis
by VulDB Data Team • 12/02/2022
The CVE-2017-8055 vulnerability resides within WatchGuard Fireware versions 11.12.1 and earlier, specifically targeting the Firebox XML-RPC login handler. This flaw represents a classic user enumeration vulnerability that exploits the inconsistent response behavior of the authentication system when processing login requests. The vulnerability manifests when a login request is submitted with a blank password to the XML-RPC agent, creating a distinguishable difference in system responses between valid and invalid usernames. This inconsistency in response handling creates a significant security risk that directly violates fundamental principles of secure authentication design and aligns with CWE-620, which addresses weaknesses in authentication mechanisms that allow for user enumeration attacks.
The technical exploitation of this vulnerability occurs through the XML-RPC interface, which serves as a remote procedure call mechanism for system management and configuration. When an attacker sends a malformed login request containing an empty password field, the system responds differently based on whether the username exists in the system's user database. Valid usernames trigger one response pattern while invalid usernames generate another, allowing attackers to systematically determine which usernames are legitimate within the target system. This behavior violates the principle of consistent error handling and demonstrates a clear breakdown in the authentication service's security posture. The vulnerability operates at the application layer and specifically targets the authentication subsystem, making it particularly dangerous as it provides attackers with a foothold for further exploitation attempts.
The operational impact of this vulnerability extends beyond simple user enumeration, as it creates a foundation for more sophisticated attacks within the compromised environment. An attacker who successfully enumerates valid usernames can then proceed to conduct brute force attacks against those accounts, leveraging the knowledge of legitimate user identities to increase attack effectiveness. The vulnerability also enables credential stuffing attacks where compromised credentials from other sources can be tested against the enumerated user base. From an attacker's perspective, this vulnerability provides a critical reconnaissance tool that significantly reduces the time and effort required to compromise the system. The impact is particularly severe in environments where user enumeration could lead to privilege escalation or lateral movement within the network, as it provides attackers with a clear understanding of the system's user landscape and potential targets.
Mitigation strategies for CVE-2017-8055 should focus on implementing consistent error handling across all authentication interfaces, ensuring that system responses remain uniform regardless of whether usernames exist in the system. Organizations should immediately upgrade to WatchGuard Fireware versions that have addressed this vulnerability, as the patch likely includes enhanced authentication mechanisms and improved response handling. Network segmentation and access controls should be implemented to limit access to XML-RPC interfaces, reducing the attack surface available to potential adversaries. Additionally, implementing account lockout mechanisms and rate limiting for authentication attempts can help prevent automated enumeration attacks from succeeding. The vulnerability demonstrates the importance of adhering to security best practices such as those outlined in the OWASP Authentication Cheat Sheet, which emphasizes the need for consistent error responses and proper account lockout mechanisms to prevent user enumeration attacks. Organizations should also consider implementing intrusion detection systems that can identify and alert on suspicious authentication patterns that may indicate enumeration attempts, as this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the credential access tactics.