CVE-2006-4877 in PHP-Post
Summary
by MITRE
Variable overwrite vulnerability in David Bennett PHP-Post (PHPp) 1.0 and earlier allows remote attackers to overwrite arbitrary program variables via multiple vectors that use the extract function, as demonstrated by the table_prefix parameter in (1) index.php, (2) profile.php, and (3) header.php.
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Analysis
by VulDB Data Team • 08/04/2018
The vulnerability described in CVE-2006-4877 represents a critical variable overwrite flaw in PHP-Post version 1.0 and earlier, which fundamentally compromises the integrity of the application's variable handling mechanisms. This issue stems from the insecure use of the extract function within multiple PHP scripts, creating a pathway for remote attackers to manipulate program variables through carefully crafted input parameters. The vulnerability affects three key files including index.php, profile.php, and header.php, demonstrating the widespread nature of the flaw across the application's core components. The extract function, when improperly utilized, allows external input to directly influence the application's internal variable namespace, creating a dangerous attack surface that can be exploited without authentication.
The technical exploitation of this vulnerability occurs through the manipulation of the table_prefix parameter, which serves as the primary vector for variable overwrites across the affected PHP files. When the extract function processes user-supplied input without proper sanitization or validation, it can overwrite critical program variables including configuration settings, authentication tokens, and other sensitive data structures. This vulnerability directly maps to CWE-128 in the Common Weakness Enumeration catalog, which classifies it as a "Variable Overwrite" weakness, specifically highlighting the insecure use of PHP's extract function in the context of user input processing. The flaw demonstrates how improper variable handling can lead to arbitrary code execution or complete system compromise when attackers can manipulate the application's runtime environment.
The operational impact of this vulnerability extends beyond simple variable overwrites to potentially enable full system compromise and unauthorized access to sensitive data. Attackers can leverage this weakness to overwrite critical application variables that control database connections, user authentication states, and access control mechanisms. This vulnerability aligns with several tactics in the MITRE ATT&CK framework, particularly those related to privilege escalation and persistence, as successful exploitation could allow attackers to manipulate the application's behavior and maintain unauthorized access. The remote nature of the attack means that exploitation can occur from any location without requiring physical access to the system, making it particularly dangerous for web applications that are publicly accessible.
The recommended mitigations for this vulnerability involve immediate code restructuring to eliminate the insecure use of the extract function and implement proper input validation and sanitization mechanisms. Developers should replace extract() calls with explicit variable assignments that only process known, safe parameters, and implement proper parameter filtering before any variable assignment occurs. The solution should include input validation that restricts the scope of variables that can be overwritten and employs a whitelist approach to parameter processing. Additionally, implementing proper access controls and input sanitization routines would prevent attackers from manipulating the table_prefix parameter and other vulnerable variables. Organizations should also consider implementing automated security scanning tools that can detect similar patterns in codebases and ensure that the application follows secure coding practices as outlined in OWASP secure coding guidelines, particularly those related to parameter validation and variable handling in PHP applications.