CVE-2006-4780 in phpBB XS
Summary
by MITRE
PHP remote file inclusion vulnerability in includes/functions.php in phpBB XS 0.58 and earlier allows remote attackers to execute arbitrary PHP code via a URL in the phpbb_root_path parameter.
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Analysis
by VulDB Data Team • 07/19/2024
The vulnerability described in CVE-2006-4780 represents a critical remote file inclusion flaw affecting phpBB XS version 0.58 and earlier. This security issue resides within the includes/functions.php file of the phpBB XS forum software, which is a lightweight extension for the popular phpBB platform. The flaw stems from insufficient input validation and sanitization mechanisms that fail to properly restrict user-supplied data from being directly incorporated into file inclusion operations. This type of vulnerability is particularly dangerous because it allows attackers to inject malicious URLs that can be executed within the context of the web server, potentially leading to complete system compromise.
The technical implementation of this vulnerability involves the phpbb_root_path parameter which is used to define the root directory path for phpBB components. When this parameter is passed directly to include or require functions without proper validation, attackers can manipulate the input to point to malicious remote files hosted on attacker-controlled servers. This creates a classic remote file inclusion (RFI) attack vector where the vulnerable application essentially becomes a vehicle for executing arbitrary code from external sources. The vulnerability is classified under CWE-98 as "Improper Control of Generation of Code ('Code Injection')" and specifically relates to CWE-88 as "Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')".
From an operational perspective, this vulnerability poses severe risks to affected systems as it enables attackers to execute arbitrary PHP code remotely without requiring authentication. The impact extends beyond simple code execution to potentially allow full system compromise, data exfiltration, and persistence mechanisms. Attackers can leverage this vulnerability to upload backdoors, establish reverse shells, or perform further reconnaissance within the network. The vulnerability affects not only individual forum installations but also the broader ecosystem of websites using vulnerable phpBB XS versions, making it particularly attractive to automated attack tools and threat actors targeting web applications. This aligns with ATT&CK technique T1190 "Exploit Public-Facing Application" and demonstrates how web application vulnerabilities can serve as initial access vectors for broader network infiltration.
The remediation strategy for CVE-2006-4780 requires immediate patching of the affected phpBB XS versions to address the input validation issues in the includes/functions.php file. Organizations should implement proper parameter validation and sanitization measures to prevent user-supplied input from being used in file inclusion operations. The recommended approach involves using allowlists of permitted values, implementing strict input validation, and avoiding direct user input in include statements. Additionally, disabling remote file inclusion capabilities in PHP configuration through the allow_url_include directive provides an additional layer of defense. System administrators should also consider implementing web application firewalls to detect and block suspicious inclusion patterns, and conduct regular security assessments to identify similar vulnerabilities in other web applications within their infrastructure. The vulnerability highlights the importance of secure coding practices and proper input validation as fundamental security controls that must be integrated into all software development processes to prevent such critical flaws from reaching production environments.