CVE-2023-33012 in ATP
Summary
by MITRE • 07/17/2023
A command injection vulnerability in the configuration parser of the Zyxel ATP series firmware versions 5.10 through 5.36 Patch 2, USG FLEX series firmware versions 5.00 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 5.10 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 5.10 through 5.36 Patch 2, and VPN series firmware versions 5.00 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands by using a crafted GRE configuration when the cloud management mode is enabled.
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Analysis
by VulDB Data Team • 07/04/2024
The CVE-2023-33012 vulnerability represents a critical command injection flaw within the configuration parser of multiple Zyxel network security devices including ATP series, USG FLEX series, USG FLEX 50(W) series, USG20(W)-VPN series, and VPN series. This vulnerability specifically affects firmware versions ranging from 5.10 through 5.36 Patch 2 across these device lines, creating a significant security risk for organizations relying on Zyxel's network infrastructure. The flaw exists in the handling of GRE (Generic Routing Encapsulation) configuration parameters when cloud management mode is enabled, allowing malicious actors to exploit this weakness through legitimate network traffic.
The technical implementation of this vulnerability stems from inadequate input validation within the firmware's configuration parser component. When the cloud management mode is active, the system processes GRE configuration data without proper sanitization of user-supplied parameters, creating an environment where crafted malicious input can be interpreted and executed as operating system commands. This type of vulnerability maps directly to CWE-77, which specifically addresses command injection flaws in software systems. The vulnerability is particularly concerning because it requires no authentication and can be exploited from within the local network, making it accessible to attackers who have already gained access to the LAN segment.
The operational impact of this vulnerability extends beyond simple unauthorized command execution, as it provides attackers with the ability to manipulate network configurations and potentially escalate their privileges within the device ecosystem. An attacker could leverage this vulnerability to modify firewall rules, alter network routing configurations, disable security features, or even gain persistent access to the network infrastructure. The cloud management mode aspect of this vulnerability is particularly dangerous because it enables remote management capabilities that can be exploited to compromise network security controls. This weakness aligns with ATT&CK technique T1059.001 for command and scripting interpreter, where adversaries use legitimate system tools to execute malicious commands.
Organizations must implement immediate mitigations to address this vulnerability, beginning with firmware updates from Zyxel to the latest available versions that contain patches for this specific flaw. Network segmentation should be implemented to limit the attack surface, ensuring that cloud management functions are not exposed to untrusted networks. Security monitoring should be enhanced to detect unusual GRE configuration changes or command execution patterns that might indicate exploitation attempts. Additionally, administrators should disable cloud management mode on devices where it is not absolutely required, as this removes the attack vector entirely. The vulnerability demonstrates the importance of secure configuration management practices and proper input validation in network security appliances, highlighting how seemingly minor parser flaws can create significant security implications across enterprise networks.