CVE-2017-11400 in Tofino Xenon Security Appliance
Summary
by MITRE
An issue has been discovered on the Belden Hirschmann Tofino Xenon Security Appliance before 03.2.00. An incomplete firmware signature allows a local attacker to upgrade the equipment (kernel, file system) with unsigned, attacker-controlled, data. This occurs because the appliance_config file is signed but the .tar.sec file is unsigned.
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Analysis
by VulDB Data Team • 12/09/2019
The Belden Hirschmann Tofino Xenon Security Appliance represents a critical network security device designed to protect industrial control systems and critical infrastructure environments. This appliance operates as a hardened security gateway that manages network traffic and enforces security policies within industrial networks. The vulnerability described in CVE-2017-11400 resides within the firmware update mechanism of this security appliance, specifically affecting versions prior to 03.2.00. This represents a fundamental flaw in the appliance's integrity verification process that could allow an attacker with local access to compromise the entire security infrastructure.
The technical flaw manifests in an incomplete firmware signature validation process where the system properly validates the appliance_config file but fails to validate the .tar.sec file that contains critical kernel and filesystem updates. This asymmetry in signature validation creates a pathway for privilege escalation and system compromise. The vulnerability stems from a lack of comprehensive cryptographic verification across all firmware components, allowing an attacker to substitute unsigned malicious code for legitimate firmware updates. This flaw directly relates to CWE-311, which describes the absence of proper cryptographic protection for sensitive data, and CWE-312, which addresses the exposure of sensitive information through incomplete data protection mechanisms.
The operational impact of this vulnerability is severe and multifaceted for industrial environments that rely on the Tofino Xenon appliance for network security. A local attacker with access to the appliance can execute arbitrary code at the kernel level, potentially gaining complete control over the security appliance's operations. This compromise could lead to the installation of persistent backdoors, modification of security policies, or the ability to bypass network security controls entirely. The attack vector requires only local access to the device, making it particularly dangerous in environments where physical security controls may be insufficient. The vulnerability affects the appliance's ability to maintain its integrity and can result in the complete subversion of the security appliance's protective functions, potentially exposing the underlying industrial network to further attacks.
Organizations utilizing the Belden Hirschmann Tofino Xenon Security Appliance should immediately implement the firmware update to version 03.2.00 or later to address this vulnerability. The recommended mitigation strategy involves verifying the integrity of all firmware components through proper cryptographic signature validation before any update installation. Network administrators should also implement strict access controls and monitoring for the appliance to detect unauthorized local access attempts. The vulnerability demonstrates the importance of comprehensive integrity verification across all system components and aligns with ATT&CK technique T1064, which covers the creation of persistence mechanisms through system modification. Additionally, this issue highlights the necessity of following security best practices outlined in NIST SP 800-53, particularly controls related to system integrity and firmware security. Organizations should also consider implementing network segmentation and monitoring to detect anomalous behavior that might indicate exploitation of this vulnerability.