CVE-2015-4599 in PHP
Summary
by MITRE
The SoapFault::__toString method in ext/soap/soap.c in PHP before 5.4.40, 5.5.x before 5.5.24, and 5.6.x before 5.6.8 allows remote attackers to obtain sensitive information, cause a denial of service (application crash), or possibly execute arbitrary code via an unexpected data type, related to a "type confusion" issue.
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Analysis
by VulDB Data Team • 05/22/2022
The vulnerability identified as CVE-2015-4599 represents a critical type confusion flaw within PHP's SOAP extension that affects multiple versions of the PHP runtime environment. This issue resides in the SoapFault::__toString method implementation within the ext/soap/soap.c file, where improper handling of unexpected data types creates dangerous conditions that can be exploited by remote attackers. The vulnerability manifests when malformed SOAP fault responses are processed, leading to unpredictable behavior that can compromise system integrity and availability.
The technical root cause of this vulnerability stems from inadequate type validation and handling within the SOAP extension's string conversion mechanism. When the SoapFault::__toString method encounters unexpected data types during fault processing, the underlying code fails to properly validate input parameters before attempting to serialize or convert them to string representations. This type confusion scenario allows attackers to manipulate the data flow and potentially trigger memory corruption issues that can result in application crashes or more severe consequences. The flaw operates at the level of type confusion as defined by CWE-128, where the system fails to properly handle data types during operations that require specific type expectations.
The operational impact of this vulnerability extends across multiple attack vectors that can be leveraged by remote adversaries. Attackers can exploit this weakness to obtain sensitive information through information disclosure mechanisms, potentially accessing system details that should remain confidential. The vulnerability also enables denial of service conditions that can cause the target application to crash and become unavailable to legitimate users. Most critically, under certain conditions, the type confusion could potentially lead to arbitrary code execution, allowing attackers to gain unauthorized control over affected systems. This vulnerability aligns with ATT&CK technique T1190 for exploitation of remote services and T1059 for command execution through compromised applications.
Organizations affected by this vulnerability should prioritize immediate remediation through version upgrades to PHP 5.4.40, 5.5.24, or 5.6.8, depending on their current PHP version. Additionally, implementing network-level mitigations such as restricting SOAP service access to trusted networks, employing web application firewalls to filter malformed SOAP requests, and monitoring for unusual patterns in SOAP fault processing can provide additional defense layers. Security teams should also conduct thorough code reviews of SOAP-related implementations to identify potential similar type confusion vulnerabilities in custom applications or third-party libraries. The remediation approach should include comprehensive testing of upgraded environments to ensure that the fix does not introduce regressions in existing SOAP functionality while maintaining proper type handling throughout the application's SOAP processing pipeline.