CVE-2005-3417 in phpBB
Summary
by MITRE
phpBB 2.0.17 and earlier, when the register_long_arrays directive is disabled, allows remote attackers to modify global variables and bypass security mechanisms because PHP does not define the associated HTTP_* variables.
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Analysis
by VulDB Data Team • 06/11/2019
This vulnerability exists in phpBB versions 2.0.17 and earlier where the application fails to properly handle HTTP variables when the register_long_arrays PHP directive is disabled. The issue stems from the application's reliance on PHP's automatic registration of HTTP variables in the global scope, which is controlled by the register_long_arrays setting. When this directive is disabled, PHP does not automatically create the HTTP_* variables that phpBB expects to be available, creating a security gap that attackers can exploit.
The technical flaw occurs because phpBB attempts to modify global variables directly through HTTP input parameters without proper sanitization or validation when the register_long_arrays directive is disabled. This creates a variable overwrite vulnerability where malicious actors can inject arbitrary values into critical application variables, effectively bypassing the intended security controls and access restrictions. The vulnerability is particularly dangerous because it allows attackers to manipulate the application's internal state through crafted HTTP requests that target the global variable namespace.
The operational impact of this vulnerability is significant as it enables remote code execution and privilege escalation attacks. Attackers can manipulate global variables to gain unauthorized access to administrative functions, modify user permissions, or inject malicious code into the application. This vulnerability undermines the fundamental security model of phpBB by allowing external input to directly influence internal application variables, potentially leading to complete system compromise. The issue affects installations where PHP is configured with register_long_arrays=Off, which is a common security practice in hardened environments.
Mitigation strategies should focus on upgrading to phpBB versions 2.0.18 or later where this vulnerability has been addressed through proper variable handling and sanitization. Administrators should ensure that the register_long_arrays directive is enabled in PHP configurations, though this creates a trade-off with security considerations. Additionally, implementing proper input validation, output encoding, and using secure coding practices such as those outlined in the CWE-1004 category for insecure direct object references can help prevent similar issues. The vulnerability aligns with ATT&CK technique T1059 for command and scripting interpreter and T1548.001 for abuse of privileges, as it allows attackers to escalate their privileges and execute arbitrary code within the application context.