CVE-2013-4635 in PHP
Summary
by MITRE
Integer overflow in the SdnToJewish function in jewish.c in the Calendar component in PHP before 5.3.26 and 5.4.x before 5.4.16 allows context-dependent attackers to cause a denial of service (application hang) via a large argument to the jdtojewish function.
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Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-4635 represents a critical integer overflow flaw within PHP's calendar manipulation functions, specifically affecting the SdnToJewish conversion routine. This issue resides in the jewish.c file within PHP's Calendar component and impacts versions prior to 5.3.26 and 5.4.16, creating a significant security risk for applications relying on Jewish calendar calculations. The vulnerability manifests when the jdtojewish function receives a large numerical argument, leading to predictable system instability.
The technical root cause of this vulnerability stems from improper integer handling within the SdnToJewish function, which fails to validate input parameters against overflow conditions. When an attacker provides an excessively large argument to the jdtojewish function, the integer overflow causes the application to enter an infinite loop or consume excessive system resources, ultimately resulting in application hang and denial of service. This type of vulnerability falls under CWE-191, Integer Underflow/Overflow, specifically manifesting as an integer overflow condition that disrupts normal program execution flow.
The operational impact of CVE-2013-4635 extends beyond simple denial of service, as it can be exploited by context-dependent attackers to disrupt web applications that utilize Jewish calendar functionality. Attackers can craft malicious requests containing oversized date parameters, causing web servers running vulnerable PHP versions to become unresponsive and potentially crash. This vulnerability is particularly dangerous in high-traffic environments where such denial of service conditions can be amplified, affecting multiple users simultaneously and potentially compromising service availability. The attack vector requires no authentication and can be executed through standard web requests, making it highly exploitable in real-world scenarios.
Mitigation strategies for this vulnerability require immediate patching of affected PHP installations to versions 5.3.26 or 5.4.16 and later, which contain the necessary fixes for integer overflow protection. System administrators should also implement input validation measures to sanitize calendar-related function parameters before processing, ensuring that date values remain within reasonable bounds. Additionally, monitoring systems should be configured to detect unusual resource consumption patterns that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with T1499.004, Network Denial of Service, and T1595.001, Network Device Denial of Service, as it can be leveraged to disrupt service availability through application-level attacks. Organizations should also consider implementing web application firewalls to detect and block malicious requests targeting this specific vulnerability pattern.