CVE-2007-1396 in PHP
Summary
by MITRE
The import_request_variables function in PHP 4.0.7 through 4.4.6, and 5.x before 5.2.2, when called without a prefix, does not prevent the (1) GET, (2) POST, (3) COOKIE, (4) FILES, (5) SERVER, (6) SESSION, and other superglobals from being overwritten, which allows remote attackers to spoof source IP address and Referer data, and have other unspecified impact. NOTE: it could be argued that this is a design limitation of PHP and that only the misuse of this feature, i.e. implementation bugs in applications, should be included in CVE. However, it has been fixed by the vendor.
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Analysis
by VulDB Data Team • 08/02/2019
The vulnerability described in CVE-2007-1396 represents a critical security flaw in PHP's import_request_variables function that affected versions from 4.0.7 through 4.4.6 and 5.x before 5.2.2. This issue stems from the function's improper handling of superglobal variable overwrites when invoked without a prefix parameter, creating a pathway for remote attackers to manipulate critical server-side variables that should remain immutable. The vulnerability specifically impacts the GET, POST, COOKIE, FILES, SERVER, SESSION, and other superglobal variables, which are fundamental components in PHP's variable handling architecture.
The technical flaw manifests when applications call import_request_variables without specifying a prefix, allowing attacker-controlled data to overwrite PHP's built-in superglobal variables that contain essential information such as source IP addresses, referer headers, and other server environment data. This behavior creates a dangerous condition where malicious actors can spoof the originating IP address of requests, manipulate referer information, and potentially influence application logic that depends on these variables. The vulnerability operates at the core level of PHP's variable import mechanism, making it particularly insidious as it affects the fundamental way applications process incoming request data.
The operational impact of this vulnerability extends beyond simple information spoofing, as it can enable various attack vectors including session hijacking, cross-site request forgery manipulation, and authentication bypass attempts. Attackers can exploit this weakness to make applications believe requests originate from trusted sources or contain specific referer information, potentially allowing them to circumvent security controls that depend on these variables. The unspecified nature of other impacts suggests this vulnerability could enable more sophisticated attacks depending on how applications utilize these superglobals, making it particularly dangerous in environments where such variables are used for access control, logging, or security validation purposes.
This vulnerability aligns with CWE-20, "Improper Input Validation," and CWE-345, "Insufficient Verification of Data Authenticity," as it involves the improper handling of input data that should remain protected from external manipulation. From an ATT&CK framework perspective, this vulnerability maps to T1059.007, "Command and Scripting Interpreter: Python," and T1566, "Phishing," as it enables attackers to manipulate request data that applications might use for validation or logging purposes. The fix implemented by PHP vendors in version 5.2.2 addressed this by modifying the function's behavior to prevent overwriting of superglobal variables, effectively closing the attack vector that allowed these manipulations to occur.
Organizations should prioritize updating affected PHP installations to versions that include the vendor-provided fix, as this vulnerability represents a fundamental flaw in how PHP processes request variables. Security teams should also conduct thorough code reviews to identify any applications that might be calling import_request_variables without proper prefix parameters, as these instances represent potential attack vectors that could be exploited by adversaries. Additionally, implementing proper input validation and sanitization practices can help mitigate the risk of exploitation, though the primary solution remains the vendor patch that prevents the overwriting of superglobal variables during the import process. The vulnerability demonstrates the importance of understanding PHP's superglobal handling mechanisms and the potential security implications of improper function usage in web application development.