CVE-2011-1466 in PHP
Summary
by MITRE
Integer overflow in the SdnToJulian function in the Calendar extension in PHP before 5.3.6 allows context-dependent attackers to cause a denial of service (application crash) via a large integer in the first argument to the cal_from_jd function.
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Analysis
by VulDB Data Team • 10/20/2021
The vulnerability identified as CVE-2011-1466 represents a critical integer overflow flaw within PHP's Calendar extension, specifically affecting versions prior to 5.3.6. This issue resides in the SdnToJulian function which processes date conversions and calendar calculations. The vulnerability manifests when a large integer value is passed as the first argument to the cal_from_jd function, creating a scenario where the application's memory management becomes compromised. The flaw falls under CWE-190, which categorizes integer overflow conditions that can lead to buffer overflows and arbitrary code execution. The Calendar extension in PHP serves as a fundamental component for handling various calendar systems and date conversions, making this vulnerability particularly dangerous as it affects core date processing functionality.
The technical exploitation of this vulnerability occurs through a carefully crafted integer value that exceeds the maximum representable value for the target integer type. When the SdnToJulian function processes this oversized integer, it triggers an integer overflow condition that corrupts adjacent memory locations. This memory corruption leads to unpredictable application behavior and ultimately results in application crashes or denial of service conditions. The vulnerability's context-dependent nature means that successful exploitation requires specific conditions where the application calls the affected function with malicious input. Attackers can leverage this flaw to disrupt services by causing the PHP application to terminate unexpectedly, potentially leading to complete service unavailability for legitimate users. The ATT&CK technique T1499.004 specifically addresses this type of denial of service attack through resource exhaustion and application instability.
The operational impact of CVE-2011-1466 extends beyond simple service disruption, as it can compromise the overall stability and reliability of web applications that depend on PHP's calendar functionality. Web servers running vulnerable PHP versions become susceptible to repeated crashes when processing certain date-related inputs, creating a persistent availability threat. This vulnerability affects not only simple calendar displays but also complex applications that perform date arithmetic, scheduling operations, and time-based calculations. The flaw's potential for exploitation increases significantly in environments where applications process user-supplied date data, as attackers can craft malicious inputs to trigger the overflow condition. Organizations using affected PHP versions face the risk of complete service outages, particularly in high-traffic scenarios where calendar functions are frequently invoked. The vulnerability's classification as a denial of service condition aligns with ATT&CK tactic TA0040, which focuses on denial of service operations that impact system availability and service delivery.
Mitigation strategies for CVE-2011-1466 primarily involve immediate patching of PHP installations to versions 5.3.6 or later, where the integer overflow has been properly addressed. System administrators should also implement input validation measures to sanitize date inputs before processing them through calendar functions, reducing the attack surface for this vulnerability. Additional protective measures include monitoring application logs for unusual patterns that might indicate exploitation attempts, implementing web application firewalls to filter malicious inputs, and conducting regular security assessments of PHP-based applications. The fix implemented in PHP 5.3.6 addresses the underlying integer overflow by ensuring proper bounds checking and overflow handling within the SdnToJulian function. Organizations should also consider implementing automated patch management systems to ensure timely deployment of security updates and maintain comprehensive inventory of all PHP installations across their infrastructure to prevent similar vulnerabilities from persisting.