CVE-2019-15518 in Swoole
Summary
by MITRE
Swoole before 4.2.13 allows directory traversal in swPort_http_static_handler.
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Analysis
by VulDB Data Team • 12/01/2023
The vulnerability identified as CVE-2019-15518 affects the Swoole PHP extension version 4.2.13 and earlier, specifically within the swPort_http_static_handler component. This issue represents a directory traversal vulnerability that enables attackers to access files outside the intended document root directory through carefully crafted HTTP requests. The flaw resides in how the HTTP static file handler processes incoming requests, particularly when handling path components that contain directory traversal sequences such as ../ or ..\.
This directory traversal vulnerability stems from insufficient input validation and sanitization within the Swoole HTTP server implementation. When processing static file requests, the system fails to properly validate or normalize file paths before attempting to serve files, allowing malicious actors to manipulate the requested file paths. The vulnerability is particularly concerning because it operates at the HTTP request processing level, meaning any application using Swoole's HTTP server functionality could be exposed to this attack vector. The flaw essentially allows an attacker to bypass normal file access controls and potentially access sensitive system files, configuration files, or other restricted resources that should not be publicly accessible through the web server interface.
The operational impact of this vulnerability extends beyond simple information disclosure, as it could potentially enable further attacks including arbitrary code execution, privilege escalation, or complete system compromise depending on the system configuration and file permissions. Attackers could leverage this vulnerability to access sensitive data such as database credentials, application configuration files, or system files that contain authentication tokens. The vulnerability affects web applications built on Swoole that serve static content, making it particularly dangerous for applications that handle sensitive data or operate in environments where security is paramount. According to CWE classification, this vulnerability maps to CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), which is a well-documented and frequently exploited weakness in web applications. The ATT&CK framework categorizes this under T1083: File and Directory Discovery, as attackers would use this vulnerability to enumerate and access files outside of normal application boundaries.
Mitigation strategies for CVE-2019-15518 primarily focus on upgrading to Swoole version 4.2.13 or later, which contains the necessary patches to address the directory traversal issue. Organizations should also implement additional defensive measures including input validation at multiple layers, proper file path normalization, and restricting the web server's access to only necessary directories. Network-level controls such as web application firewalls can provide additional protection by filtering out suspicious path traversal sequences in HTTP requests. Security teams should conduct thorough vulnerability assessments to identify all systems using affected Swoole versions and ensure proper patch management procedures are in place to prevent similar issues from arising in the future. The remediation process should also include monitoring for suspicious file access patterns and implementing proper logging to detect potential exploitation attempts.