CVE-2011-1470 in PHP
Summary
by MITRE
The Zip extension in PHP before 5.3.6 allows context-dependent attackers to cause a denial of service (application crash) via a ziparchive stream that is not properly handled by the stream_get_contents function.
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Analysis
by VulDB Data Team • 11/24/2024
The vulnerability identified as CVE-2011-1470 represents a critical denial of service weakness within PHP's Zip extension that existed in versions prior to 5.3.6. This flaw specifically targets the ziparchive stream handling mechanism and exploits a deficiency in how the stream_get_contents function processes malformed or improperly structured zip archive streams. The vulnerability operates within the context-dependent attack model, meaning that successful exploitation requires specific conditions related to how zip archives are accessed and processed within PHP applications. The issue manifests when PHP applications attempt to read zip archive contents using the stream_get_contents function, which fails to properly validate or handle certain edge cases in zip stream structures.
The technical root cause of this vulnerability stems from inadequate input validation and error handling within the ziparchive stream implementation. When PHP processes a zip archive through the stream_get_contents function, the underlying code does not sufficiently sanitize or validate the stream data, particularly when encountering malformed zip headers, corrupted archive structures, or unusual compression formats. This deficiency creates a scenario where maliciously crafted zip streams can trigger memory access violations or stack corruption within the PHP interpreter, ultimately leading to application crashes and complete service unavailability. The vulnerability falls under the category of improper input validation as classified by CWE-20, specifically involving stream handling functions that fail to properly process edge cases in data streams.
From an operational impact perspective, this vulnerability presents a significant threat to web applications that rely on PHP for file processing or archive handling functionalities. Attackers can exploit this weakness to disrupt services by uploading or accessing specially crafted zip files that trigger the application crash when the stream_get_contents function attempts to read the archive contents. The denial of service effect can be particularly severe in high-traffic environments where multiple concurrent requests might be processed, potentially leading to cascading failures across dependent systems. The vulnerability affects any PHP application that utilizes ziparchive functionality, including content management systems, file upload handlers, and any application that processes user-supplied zip files. This weakness can be leveraged in distributed denial of service attacks or as part of broader exploitation campaigns targeting PHP-based web infrastructure.
The mitigation strategy for CVE-2011-1470 primarily involves upgrading PHP installations to version 5.3.6 or later, where the vulnerability has been addressed through improved stream handling and input validation mechanisms. System administrators should also implement additional protective measures such as validating user-uploaded files before processing, implementing proper file type restrictions, and monitoring for unusual patterns in zip archive handling. Organizations should consider implementing web application firewalls that can detect and block suspicious zip archive requests, as well as establishing robust error handling procedures that prevent application crashes from affecting overall system availability. The remediation process should include comprehensive testing of all PHP applications that utilize ziparchive functionality to ensure that the upgrade does not introduce compatibility issues while effectively addressing the vulnerability. This vulnerability aligns with ATT&CK technique T1499.004 for network denial of service and represents a classic example of how stream handling flaws can lead to critical system availability issues in web applications.