CVE-2018-12542 in Vert.x
Summary
by MITRE
In version from 3.0.0 to 3.5.3 of Eclipse Vert.x, the StaticHandler uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize '\' (forward slashes) sequences that can resolve to a location that is outside of that directory when running on Windows Operating Systems.
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Analysis
by VulDB Data Team • 05/25/2023
The vulnerability identified as CVE-2018-12542 affects Eclipse Vert.x versions 3.0.0 through 3.5.3 and represents a directory traversal flaw in the StaticHandler component. This issue specifically manifests when the application operates on Windows operating systems where the path resolution behavior differs from Unix-like systems. The vulnerability stems from inadequate input validation and path normalization within the handler's implementation, creating a security risk that allows unauthorized access to files outside the intended directory boundaries.
The technical flaw occurs because the StaticHandler component accepts external input to construct file paths but fails to properly sanitize forward slash characters in the input data. On Windows systems, the backslash character serves as both a path separator and a directory traversal indicator, creating opportunities for attackers to manipulate the path resolution logic. When malicious input containing sequences like '../' or similar traversal patterns is processed, the handler does not adequately neutralize these sequences, allowing them to be interpreted as legitimate path navigation commands rather than malicious input.
This vulnerability operates under the Common Weakness Enumeration CWE-22 category, which classifies it as a "Path Traversal" or "Directory Traversal" weakness. The operational impact of this flaw is significant as it enables attackers to access files that should be restricted to the application's designated directory structure. On Windows systems, where the vulnerability is most pronounced, an attacker could potentially access system files, configuration files, or other sensitive resources that reside outside the intended web root or static content directory. The attack vector is particularly concerning because it leverages the platform-specific behavior of path resolution, making it more difficult to detect and prevent through generic security measures.
The security implications extend beyond simple file access, as this vulnerability could enable attackers to retrieve sensitive information such as application configuration files, database connection details, or other system credentials that might be stored in accessible locations. Additionally, the vulnerability could be exploited to access log files or other sensitive data that might contain authentication tokens, session information, or other confidential data. The attack requires minimal privileges and can be executed through standard HTTP requests, making it particularly dangerous for web applications that serve static content.
Organizations using affected Eclipse Vert.x versions should immediately upgrade to versions 3.5.4 or later, where the vulnerability has been addressed through proper input sanitization and path normalization. The mitigation strategy should include implementing proper input validation at multiple layers, including the application level and potentially at the network level through web application firewalls. Security teams should also conduct thorough audits of their static content directories to ensure no unauthorized access paths exist and implement monitoring for suspicious file access patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of platform-specific security considerations in application development, particularly when dealing with file system operations that may behave differently across operating systems.