CVE-2015-4600 in PHP
Summary
by MITRE
The SoapClient implementation 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 cause a denial of service (application crash) or possibly execute arbitrary code via an unexpected data type, related to "type confusion" issues in the (1) SoapClient::__getLastRequest, (2) SoapClient::__getLastResponse, (3) SoapClient::__getLastRequestHeaders, (4) SoapClient::__getLastResponseHeaders, (5) SoapClient::__getCookies, and (6) SoapClient::__setCookie methods.
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Analysis
by VulDB Data Team • 05/22/2022
The vulnerability identified as CVE-2015-4600 represents a critical type confusion issue within PHP's SoapClient implementation that affects multiple versions of the PHP runtime environment. This flaw exists in the way PHP handles data type validation during SOAP request and response processing, creating opportunities for remote attackers to manipulate the application's behavior through carefully crafted input data. The vulnerability specifically impacts the SoapClient class methods that handle request and response metadata, including __getLastRequest, __getLastResponse, __getLastRequestHeaders, __getLastResponseHeaders, __getCookies, and __setCookie operations.
The technical root cause of this vulnerability stems from insufficient type checking and validation within the SOAP client implementation, leading to type confusion scenarios where the application incorrectly interprets data types during method execution. When attackers provide unexpected data types to these specific SoapClient methods, the application's internal type handling mechanisms fail to properly validate the input, potentially causing memory corruption or unexpected execution paths. This type confusion vulnerability operates at the intersection of CWE-129 and CWE-131, representing both improper input validation and incorrect handling of memory operations. The flaw allows attackers to manipulate the application's execution flow through carefully crafted SOAP responses or headers that trigger unexpected type conversions.
The operational impact of CVE-2015-4600 extends beyond simple denial of service to potentially enable remote code execution on vulnerable systems. Attackers can leverage this vulnerability to cause application crashes that result in service disruption, or more severely, to execute arbitrary code on the target system with the privileges of the PHP process. This makes the vulnerability particularly dangerous in web server environments where PHP applications handle untrusted SOAP data from external sources. The attack surface includes any PHP application that utilizes SoapClient functionality and processes external SOAP requests, making it a widespread concern across numerous web applications and services that depend on SOAP communication protocols.
Mitigation strategies for CVE-2015-4600 primarily focus on immediate patching of affected PHP versions, with the recommended approach being the upgrade to PHP versions 5.4.40, 5.5.24, or 5.6.8, which contain the necessary fixes for the type confusion issues. Organizations should implement comprehensive input validation measures to sanitize all SOAP request and response data before processing, particularly focusing on the metadata methods mentioned in the vulnerability description. Network-level defenses such as firewalls and intrusion prevention systems can help by monitoring for suspicious SOAP traffic patterns, though these measures are not foolproof against determined attackers. Additionally, the implementation of proper error handling and application-level logging can aid in detecting exploitation attempts, while the principle of least privilege should be enforced to limit potential damage from successful attacks. From an ATT&CK framework perspective, this vulnerability maps to T1203 (Exploitation for Client Execution) and T1499 (Endpoint Denial of Service) techniques, highlighting the dual nature of the threat as both a service disruption vector and a potential code execution pathway.