CVE-2020-14366 in KeyCloak
Summary
by MITRE • 11/10/2020
A vulnerability was found in keycloak, where path traversal using URL-encoded path segments in the request is possible because the resources endpoint applies a transformation of the url path to the file path. Only few specific folder hierarchies can be exposed by this flaw
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability identified as CVE-2020-14366 represents a critical path traversal flaw within the Keycloak identity and access management platform. This security weakness stems from the improper handling of URL-encoded path segments in the resources endpoint, where the system transforms URL paths directly into file system paths without adequate validation or sanitization. The vulnerability specifically affects the way Keycloak processes incoming requests that contain encoded path components, allowing malicious actors to manipulate URL structures to access unauthorized file system resources. The flaw operates through a transformation mechanism that maps URL segments to file system paths, creating a direct mapping that bypasses normal access controls and file system boundaries. This type of vulnerability falls under the CWE-22 category, which specifically addresses path traversal or directory traversal attacks, making it a well-documented and dangerous class of security flaw that has been exploited in numerous systems across various platforms. The impact is particularly concerning given Keycloak's widespread adoption in enterprise environments where it serves as a central authentication and authorization service, making it a prime target for attackers seeking to escalate privileges or access sensitive configuration files, user data, or system resources.
The technical exploitation of this vulnerability requires understanding how Keycloak's resource endpoint processes incoming requests and translates them into file system operations. When a request contains URL-encoded path segments such as %2e%2e%2f (which translates to ../), the system fails to properly decode and validate these components before applying them to file system operations. This allows attackers to traverse directory structures and access files that should normally be restricted or protected. The vulnerability is limited in scope compared to full path traversal attacks, as it only affects specific folder hierarchies within Keycloak's resource structure, but this targeted nature makes it particularly dangerous for attackers who can identify the accessible directories. The flaw demonstrates a classic security misconfiguration where input validation occurs too late in the processing pipeline, after the URL has already been partially transformed into a file path. This vulnerability aligns with ATT&CK technique T1083, which covers directory and file discovery, as it enables attackers to enumerate and access unauthorized file system locations. The transformation process creates a direct mapping between web request paths and file system locations without proper boundary checking, which represents a fundamental flaw in the application's security architecture.
The operational impact of CVE-2020-14366 extends beyond simple unauthorized file access, as it can potentially lead to full system compromise depending on the exposed resources and the privileges of the Keycloak service account. Attackers who successfully exploit this vulnerability could access sensitive configuration files that may contain database credentials, encryption keys, or other critical system information. The exposed resources could include application logs, backup files, or even source code repositories that might contain additional vulnerabilities or sensitive data. The limited scope of affected folder hierarchies does not diminish the severity of the issue, as these directories often contain the most critical system components and user data. Organizations using Keycloak in production environments face significant risk from this vulnerability, particularly those that have not implemented additional security controls or network segmentation. The vulnerability's impact is amplified in environments where Keycloak serves as a central authentication point, as successful exploitation could potentially provide attackers with access to multiple systems or applications that rely on Keycloak for authentication. This type of vulnerability also represents a significant concern for compliance requirements, as it could lead to violations of data protection regulations and security standards such as those outlined in the NIST Cybersecurity Framework. The attack surface for this vulnerability includes not only direct exploitation but also potential use in combination with other techniques such as credential theft or privilege escalation, making it a multi-faceted threat to system security. Organizations should prioritize immediate remediation of this vulnerability through official patches or updates from Keycloak vendors, as the flaw represents a persistent risk to system integrity and data confidentiality.
The mitigation strategies for CVE-2020-14366 should focus on implementing proper input validation and sanitization at the point where URL paths are transformed into file system operations. Organizations should ensure that all path traversal attempts are properly validated and that URL-encoded components are decoded and checked against allowed directories before any file system operations are performed. The implementation of a whitelist approach for valid directory access, combined with proper path normalization and canonicalization, can effectively prevent this class of vulnerability. Security measures should include network-level restrictions that limit access to Keycloak endpoints and implement proper monitoring for unusual path traversal patterns in access logs. Additionally, organizations should consider implementing application firewalls or web application firewalls that can detect and block suspicious path traversal attempts. The vulnerability highlights the importance of following security best practices such as the principle of least privilege, where Keycloak services should operate with minimal required permissions to reduce the potential impact of successful exploitation. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the authentication and authorization infrastructure. The remediation process should also include comprehensive testing to ensure that security patches do not introduce regressions or break existing functionality while maintaining the system's intended capabilities. Organizations should also consider implementing additional logging and alerting mechanisms specifically designed to detect path traversal attempts, which can provide early warning of potential exploitation attempts and support incident response activities.