CVE-2002-1704 in Zeroboard
Summary
by MITRE
Zeroboard 4.1, when the "allow_url_fopen" and "register_globals" variables are enabled, allows remote attackers to execute arbitrary PHP code by modifying the _zb_path parameter to reference a URL on a remote web server that contains the code.
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Analysis
by VulDB Data Team • 02/08/2025
CVE-2002-1704 represents a critical remote code execution vulnerability affecting Zeroboard 4.1 web applications. This vulnerability stems from improper input validation and unsafe configuration practices that create dangerous attack vectors for remote adversaries. The flaw specifically leverages two dangerous PHP configuration settings that, when enabled simultaneously, permit malicious code injection through crafted URL parameters. The vulnerability operates under CWE-94, which classifies it as an improper control of generation of code, representing a classic code injection flaw that allows attackers to execute arbitrary commands on the target system.
The technical exploitation mechanism involves manipulation of the _zb_path parameter within the Zeroboard application's URL handling logic. When both allow_url_fopen and register_globals are enabled, the application fails to properly sanitize user input before processing it in contexts that can execute PHP code. Attackers can craft malicious URLs that include the _zb_path parameter pointing to remote web servers hosting malicious PHP code. The allow_url_fopen directive permits PHP to open remote files via URLs, while register_globals creates a dangerous environment where external parameters automatically become global variables, bypassing normal input validation mechanisms. This combination creates a perfect storm for remote code execution attacks, as demonstrated by the ATT&CK technique T1190 - Exploit Public-Facing Application, which specifically addresses vulnerabilities in web applications that allow remote code execution.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with complete control over the affected web server. Once successfully exploited, attackers can upload additional malicious files, establish persistent backdoors, escalate privileges, and potentially use the compromised server as a launchpad for further attacks against internal networks. The vulnerability affects the application's core functionality by allowing arbitrary PHP code execution, which can lead to data theft, service disruption, and complete system compromise. The risk is particularly severe because it requires only basic web browsing capabilities to exploit, making it accessible to attackers with minimal technical expertise. Organizations running vulnerable Zeroboard installations face significant exposure to unauthorized access and potential data breaches, with the attack surface extending to any system where these dangerous PHP configurations are enabled.
Mitigation strategies for CVE-2002-1704 focus on immediate configuration changes and application hardening measures. The most effective immediate fix involves disabling both allow_url_fopen and register_globals PHP directives in the php.ini configuration file, which eliminates the core conditions necessary for exploitation. Additionally, implementing proper input validation and sanitization throughout the application codebase prevents malicious parameters from being processed as executable code. Web application firewalls can provide additional protection by filtering suspicious URL patterns and monitoring for known attack signatures. Regular security audits and vulnerability assessments should be conducted to identify similar misconfigurations across the entire infrastructure. The remediation process should also include updating to patched versions of Zeroboard, as version 4.1 contains multiple vulnerabilities that require comprehensive security updates to address. Organizations should also implement network segmentation and access controls to limit the potential impact of successful exploitation attempts, following ATT&CK framework recommendations for defending against application-level attacks through layered security approaches.