CVE-2016-7418 in macOS
Summary
by MITRE
The php_wddx_push_element function in ext/wddx/wddx.c in PHP before 5.6.26 and 7.x before 7.0.11 allows remote attackers to cause a denial of service (invalid pointer access and out-of-bounds read) or possibly have unspecified other impact via an incorrect boolean element in a wddxPacket XML document, leading to mishandling in a wddx_deserialize call.
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Analysis
by VulDB Data Team • 10/07/2022
The vulnerability identified as CVE-2016-7418 represents a critical security flaw in the PHP web application scripting language that affects versions prior to 5.6.26 and 7.0.11. This issue resides within the php_wddx_push_element function located in the ext/wddx/wddx.c file, which handles the serialization and deserialization of WDDX (Web Distributed Data Exchange) packets. WDDX is a platform-independent data interchange format that allows data to be transmitted between different systems, and PHP's implementation of this protocol through the wddx_deserialize function creates a potential attack surface when processing malformed XML documents.
The technical flaw manifests when PHP processes a wddxPacket XML document containing an incorrect boolean element, which triggers improper handling within the wddx_deserialize call mechanism. This vulnerability enables attackers to craft malicious XML payloads that, when processed by the vulnerable PHP application, result in invalid pointer access and out-of-bounds read conditions. These memory corruption issues arise from insufficient input validation and boundary checking during the deserialization process, allowing attackers to manipulate the program's memory access patterns and potentially execute arbitrary code or cause the application to crash.
The operational impact of this vulnerability extends beyond simple denial of service, as the out-of-bounds read conditions can lead to information disclosure, arbitrary code execution, or system instability. Attackers exploiting this vulnerability can cause PHP applications to behave unpredictably, potentially leading to complete system compromise when combined with other exploitation techniques. The vulnerability affects web applications that utilize WDDX functionality for data interchange, particularly those that deserialize user-provided XML data without proper sanitization, creating a significant risk for applications handling external data inputs.
From a cybersecurity perspective, this vulnerability aligns with CWE-125, which addresses out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write vulnerabilities. The attack vector follows ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain unauthorized access or execute malicious code. Organizations should implement immediate mitigation strategies including upgrading to patched PHP versions, implementing proper input validation for all XML data processing, and deploying web application firewalls to detect and block malicious WDDX packet payloads. Additionally, developers should avoid using vulnerable functions when possible and ensure that all external XML data is properly sanitized and validated before processing to prevent exploitation of similar memory corruption vulnerabilities in the application stack.