CVE-2016-6288 in macOS
Summary
by MITRE
The php_url_parse_ex function in ext/standard/url.c in PHP before 5.5.38 allows remote attackers to cause a denial of service (buffer over-read) or possibly have unspecified other impact via vectors involving the smart_str data type.
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Analysis
by VulDB Data Team • 09/20/2022
The vulnerability identified as CVE-2016-6288 represents a critical buffer over-read flaw within the PHP web application scripting engine that affects versions prior to 5.5.38. This issue resides in the php_url_parse_ex function located in the ext/standard/url.c source file, which is responsible for parsing URL structures within PHP applications. The flaw specifically manifests when processing certain malformed URL inputs that trigger improper handling of the smart_str data type, creating conditions where memory access violations can occur.
The technical exploitation of this vulnerability occurs through carefully crafted URL inputs that cause the smart_str data structure to overflow beyond its allocated memory boundaries during URL parsing operations. This buffer over-read condition can result in unpredictable program behavior, including application crashes that manifest as denial of service conditions. The vulnerability's impact extends beyond simple service disruption as the over-read may potentially expose sensitive memory contents or allow attackers to manipulate program execution flow, though the exact nature of additional impacts remains unspecified in the original reporting.
From an operational perspective, this vulnerability poses significant risks to PHP-based web applications that process user-supplied URL data without proper validation. Attackers can leverage this flaw by submitting maliciously formatted URLs to trigger the buffer over-read condition, potentially causing web server processes to crash or behave unpredictably. The vulnerability is particularly dangerous in environments where PHP applications handle external URL inputs from untrusted sources, such as web forms, API endpoints, or URL redirection mechanisms. This makes the attack surface broad across various web application types including content management systems, e-commerce platforms, and web services that rely on PHP for backend processing.
The vulnerability maps to CWE-121 Stack-based Buffer Overflow and CWE-125 Out-of-bounds Read within the Common Weakness Enumeration framework, indicating both buffer management issues and memory access violations. From an attack framework perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1059.007 Execution via Scripting category, where attackers can leverage scripting language vulnerabilities to execute malicious code or cause system instability. The attack vector typically involves web-based exploitation where remote attackers submit crafted URL parameters to trigger the buffer over-read condition in the PHP runtime environment.
Mitigation strategies for CVE-2016-6288 primarily focus on immediate patching of affected PHP installations to versions 5.5.38 or later where the vulnerability has been resolved. System administrators should implement comprehensive input validation mechanisms that sanitize all URL inputs before processing, particularly for applications that handle external URL data. Additionally, deploying web application firewalls and implementing proper error handling can help detect and prevent exploitation attempts. Organizations should also conduct thorough vulnerability assessments to identify all PHP installations within their environment and ensure all systems are updated to patched versions. Network monitoring should be enhanced to detect potential exploitation attempts through unusual patterns of URL processing or application crashes that may indicate successful exploitation of this vulnerability.