CVE-2021-4030 in ARMOR Z1
Summary
by MITRE • 02/24/2022
A cross-site request forgery vulnerability in the HTTP daemon of the Zyxel ARMOR Z1/Z2 firmware could allow an attacker to execute arbitrary commands if they coerce or trick a local user to visit a compromised website with malicious scripts.
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Analysis
by VulDB Data Team • 02/26/2022
This cross-site request forgery vulnerability exists within the HTTP daemon component of Zyxel ARMOR Z1/Z2 firmware versions, representing a critical security flaw that undermines the device's authentication mechanisms. The vulnerability stems from insufficient validation of HTTP requests originating from external sources, allowing malicious actors to craft forged requests that appear legitimate to the device's web interface. The flaw enables attackers to manipulate the device's configuration through crafted web requests, potentially leading to complete system compromise. According to CWE-352, this vulnerability specifically maps to Cross-Site Request Forgery, where the application fails to verify the authenticity of requests originating from authenticated sessions. The attack vector requires social engineering to trick local users into visiting malicious websites, making it particularly dangerous as it leverages user trust and browser-based execution contexts.
The technical implementation of this vulnerability involves the HTTP daemon failing to properly validate request origins and implement anti-CSRF tokens or similar protective measures. When legitimate users access the device's web interface, the system does not adequately distinguish between authorized requests from the user's browser and maliciously crafted requests from external domains. This allows attackers to construct specially crafted web pages containing embedded scripts that automatically submit commands to the vulnerable device when users browse to these malicious sites. The exploitation process typically involves creating a webpage with embedded forms or javascript that submits requests to the device's administrative interface, potentially executing arbitrary commands with the privileges of the authenticated user.
The operational impact of this vulnerability extends beyond simple privilege escalation, as successful exploitation can result in complete device compromise and potential network infiltration. Attackers can leverage this vulnerability to modify device configurations, install malicious software, or establish persistent backdoors within the network infrastructure. The ARMOR Z1/Z2 devices serve as network security appliances, making their compromise particularly dangerous as it could provide attackers with unauthorized access to protected network segments. From an ATT&CK framework perspective, this vulnerability aligns with T1078 Valid Accounts and T1566 Phishing techniques, where adversaries use social engineering to gain access to legitimate user accounts and then exploit weak session management controls. The vulnerability affects both local and potentially remote attack scenarios, depending on the device's network exposure and configuration.
Mitigation strategies for this vulnerability should focus on implementing proper CSRF protection mechanisms within the HTTP daemon, including the deployment of anti-CSRF tokens, strict origin validation, and referer header checking. Network administrators should immediately update firmware to versions that address this vulnerability, as Zyxel has released patches for affected devices. Additional protective measures include implementing network segmentation to limit direct access to administrative interfaces, configuring strict firewall rules to restrict access to device management ports, and deploying intrusion detection systems to monitor for suspicious web requests. The vulnerability highlights the importance of secure session management and proper input validation in web applications, as outlined in OWASP Top Ten security principles and NIST SP 800-53 security controls. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in network infrastructure devices and ensure comprehensive protection against credential theft and unauthorized access attempts.