CVE-2023-6545 in TwinCAT BSD
Summary
by MITRE • 12/14/2023
The package authelia-bhf included in Beckhoffs TwinCAT/BSD is prone to an open redirect that allows a remote unprivileged attacker to redirect a user to another site. This may have limited impact to integrity and does solely affect anthelia-bhf the Beckhoff fork of authelia.
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Analysis
by VulDB Data Team • 01/10/2024
The vulnerability identified as CVE-2023-6545 affects the authelia-bhf package, which is a Beckhoff-specific fork of the Authelia authentication and authorization solution. This package is integrated into Beckhoff's TwinCAT/BSD operating system environment, which is commonly used in industrial automation and control systems. The flaw manifests as an open redirect vulnerability that enables remote unprivileged attackers to manipulate user redirection flows within the authentication system. This type of vulnerability falls under the category of CWE-601, which specifically addresses open redirect vulnerabilities where applications redirect users to external domains without proper validation. The affected component represents a specialized version of Authelia designed for Beckhoff's industrial automation platform, distinguishing it from the standard Authelia implementation used in general-purpose environments.
The technical implementation of this vulnerability stems from insufficient validation of redirect URLs within the authentication flow of the authelia-bhf package. When users attempt to access protected resources or navigate through the authentication system, the application fails to properly sanitize or validate the target URLs that users are redirected to after successful authentication or during login processes. This weakness allows attackers to craft malicious URLs that contain crafted redirect parameters pointing to external domains controlled by the attacker. The vulnerability specifically impacts the Beckhoff fork of Authelia, indicating that the standard Authelia implementation may not contain this particular flaw, though similar issues could potentially exist in other derivative implementations. Attackers can exploit this vulnerability by constructing specially crafted links that, when clicked by authenticated users, will redirect them to malicious websites.
The operational impact of this vulnerability extends beyond simple redirection, as it creates potential attack vectors for social engineering and phishing campaigns within industrial environments. While the vulnerability is classified as having limited impact to data integrity, it can still serve as a stepping stone for more sophisticated attacks. An attacker could redirect users to malicious sites that attempt to harvest credentials or deploy malware, particularly in industrial settings where operators might be less vigilant about unusual redirects. The vulnerability affects the Beckhoff TwinCAT/BSD environment, which is widely used in critical infrastructure and industrial control systems, making this issue particularly concerning from a cybersecurity perspective. The open redirect could be leveraged to create convincing phishing attacks that appear legitimate within the context of the industrial automation environment. This type of vulnerability can undermine user trust in the authentication system and potentially provide attackers with opportunities to escalate privileges or gain unauthorized access to industrial control systems.
Mitigation strategies for CVE-2023-6545 should focus on implementing proper URL validation and sanitization within the authelia-bhf package. Organizations should ensure that all redirect URLs are validated against a strict whitelist of approved domains or that absolute URLs are properly validated to prevent redirection to external domains. The recommended approach involves implementing a robust validation mechanism that checks redirect targets against a predefined list of trusted domains or employs a secure redirect function that ensures users are only redirected to internal resources. System administrators should also consider implementing network-level controls to monitor and block suspicious redirect traffic, as well as conducting regular security assessments of industrial automation environments. According to ATT&CK framework category T1566, which covers Phishing techniques, this vulnerability can be exploited as part of a broader attack chain involving social engineering and credential theft. Organizations should also consider updating to patched versions of the authelia-bhf package when available and implementing additional security controls such as network segmentation and user access controls to limit the potential impact of successful exploitation. Regular security monitoring and incident response procedures should be enhanced to detect and respond to suspicious redirect activities within industrial control systems.