CVE-2007-5099 in Helplink
Summary
by MITRE
PHP remote file inclusion vulnerability in show.php in David Watters Helplink 0.1.0 allows remote attackers to execute arbitrary PHP code via a URL in the file parameter.
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Analysis
by VulDB Data Team • 10/07/2024
The vulnerability identified as CVE-2007-5099 represents a critical remote file inclusion flaw in the David Watters Helplink 0.1.0 web application, specifically within the show.php script. This vulnerability falls under the category of insecure direct object references and improper input validation, creating a pathway for malicious actors to execute arbitrary code on the target system. The flaw stems from the application's failure to properly validate and sanitize user-supplied input parameters, particularly the file parameter that controls which file to include and display. When an attacker supplies a malicious URL in the file parameter, the application processes this input without adequate sanitization, allowing the inclusion of remote files that may contain malicious PHP code. This vulnerability directly maps to CWE-88, which describes improper neutralization of argument separators in a command, and CWE-94, which covers improper execution of code, both of which are fundamental to the exploitation mechanism. The security implications are severe as this allows attackers to execute arbitrary commands on the vulnerable server, potentially leading to complete system compromise, data exfiltration, and persistence within the network environment.
The technical exploitation of this vulnerability occurs through the manipulation of the file parameter in the show.php script, where the application uses user input to determine which file to include via PHP's include or require functions. This primitive inclusion mechanism without proper input validation creates a direct attack surface where remote code execution becomes possible. Attackers can leverage this by crafting malicious URLs that point to remote servers hosting malicious PHP payloads, which are then executed on the target server. The vulnerability is particularly dangerous because it does not require authentication or special privileges to exploit, making it a high-severity issue that can be exploited by anyone with access to the vulnerable application. The attack pattern aligns with the techniques described in the MITRE ATT&CK framework under the T1059.007 technique for command and scripting interpreter, specifically focusing on PHP script execution. This vulnerability demonstrates the classic remote file inclusion attack pattern where an attacker's input is directly incorporated into a server-side include directive, bypassing normal security controls and validation mechanisms.
The operational impact of CVE-2007-5099 extends beyond simple code execution to encompass complete system compromise and potential lateral movement within the network. Once an attacker successfully exploits this vulnerability, they can establish persistent access, install backdoors, and exfiltrate sensitive data from the compromised server. The vulnerability affects the confidentiality, integrity, and availability of the targeted system, as attackers can modify files, delete data, and disrupt services. Organizations running vulnerable versions of David Watters Helplink 0.1.0 face significant risk of unauthorized access, data breaches, and potential regulatory compliance violations. The exploitation of this vulnerability can lead to cascading security incidents where the compromised server becomes a pivot point for attacking other systems within the network infrastructure. Additionally, the vulnerability may be automatically detected and exploited by automated scanning tools, increasing the attack surface and frequency of exploitation attempts. The lack of proper input validation and sanitization in this application demonstrates a fundamental flaw in secure coding practices, highlighting the importance of implementing proper parameter validation and secure coding standards to prevent such critical vulnerabilities from being introduced into web applications.
The recommended mitigations for this vulnerability involve implementing multiple layers of defense to prevent remote file inclusion attacks. The primary remediation strategy requires modifying the show.php script to validate and sanitize all user input parameters, particularly those used in file inclusion operations. This includes implementing strict input validation that only accepts predefined, whitelisted values for the file parameter, rejecting any input that contains remote URL schemes or suspicious characters. Organizations should also implement proper parameter validation using allowlists rather than denylists, ensuring that only expected and safe file paths are processed. The application should be updated to use absolute paths for file inclusion operations and avoid dynamic inclusion based on user input. Additional security measures include implementing web application firewalls to detect and block malicious requests, disabling dangerous PHP functions like allow_url_include, and ensuring proper file permissions and access controls. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other application components, while implementing proper input validation and sanitization practices throughout the application development lifecycle. The remediation efforts should also include monitoring for exploitation attempts and establishing incident response procedures to quickly address any successful attacks on vulnerable systems.