CVE-2007-1824 in PHP
Summary
by MITRE
Buffer overflow in the php_stream_filter_create function in PHP 5 before 5.2.1 allows remote attackers to cause a denial of service (application crash) via a php://filter/ URL that has a name ending in the . character.
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Analysis
by VulDB Data Team • 07/23/2019
The vulnerability identified as CVE-2007-1824 represents a critical buffer overflow flaw within the PHP streaming filter mechanism that affects PHP versions prior to 5.2.1. This issue specifically targets the php_stream_filter_create function which is responsible for handling php://filter URLs used for stream filtering operations in the PHP runtime environment. The flaw manifests when processing specially crafted URLs that contain filter names ending with a period character, creating a condition where insufficient bounds checking allows memory corruption to occur during the parsing and processing of these malformed filter specifications.
The technical implementation of this vulnerability stems from inadequate input validation within the stream filter creation logic where the PHP engine fails to properly sanitize filter name parameters before processing them. When a malicious user crafts a php://filter/ URL with a name that terminates in a period character, the internal buffer management routines do not correctly handle the trailing character, leading to memory overwrite conditions that can result in arbitrary code execution or application termination. This type of vulnerability falls under the CWE-121 category of stack-based buffer overflow, though it manifests in a more complex memory management scenario within the PHP stream filter subsystem. The attack vector is particularly dangerous because it can be exploited through web-based interfaces where PHP processes user-supplied URLs, making it a significant threat to web applications that utilize stream filtering functionality.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable more sophisticated attacks depending on the target environment and application configuration. When exploited successfully, the buffer overflow can cause the PHP process to crash and restart, leading to service disruption and potential information disclosure through memory dumps. In web server environments, this vulnerability could allow attackers to repeatedly crash PHP processes, effectively creating a persistent denial of service condition that impacts legitimate users. The vulnerability is particularly concerning in shared hosting environments where multiple applications might be running under the same PHP process, as exploitation could affect other applications hosted on the same server. According to ATT&CK framework categorization, this vulnerability maps to T1499.004 for network denial of service and potentially T1595.001 for reconnaissance activities that precede exploitation attempts.
Mitigation strategies for CVE-2007-1824 require immediate implementation of the official PHP security patch that addresses the buffer overflow in the php_stream_filter_create function. System administrators should upgrade to PHP 5.2.1 or later versions where this vulnerability has been resolved through proper bounds checking and input sanitization mechanisms. Additionally, organizations should implement network-level protections such as web application firewalls that can detect and block suspicious php://filter URL patterns, particularly those ending with period characters. Input validation should be enhanced at the application level to sanitize all user-supplied URLs before processing them through PHP stream operations, and access controls should be implemented to restrict the use of stream filtering functions where possible. Security monitoring should include detection of unusual PHP process restarts or crash patterns that may indicate exploitation attempts, and regular security audits should verify that no legacy PHP installations remain vulnerable to this and similar historical vulnerabilities. The patch implementation addresses the root cause by ensuring proper buffer size calculations and memory allocation handling within the stream filter creation process, preventing the overflow condition that previously allowed malicious input to corrupt memory structures.