CVE-2023-4760 in RAP
Summary
by MITRE • 09/21/2023
In Eclipse RAP versions from 3.0.0 up to and including 3.25.0, Remote Code Execution is possible on Windows when using the FileUpload component.
The reason for this is a not completely secure extraction of the file name in the FileUploadProcessor.stripFileName(String name) method. As soon as this finds a / in the path, everything before it is removed, but potentially \ (backslashes) coming further back are kept.
For example, a file name such as /..\..\webapps\shell.war can be used to upload a file to a Tomcat server under Windows, which is then saved as ..\..\webapps\shell.war in its webapps directory and can then be executed.
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Analysis
by VulDB Data Team • 10/14/2023
The vulnerability identified as CVE-2023-4760 affects Eclipse RAP versions 3.0.0 through 3.25.0 and represents a critical remote code execution flaw that specifically targets Windows environments utilizing the FileUpload component. This vulnerability stems from inadequate input validation within the FileUploadProcessor.stripFileName(String name) method, creating a path traversal condition that allows attackers to manipulate file upload operations. The flaw demonstrates a classic security oversight where the system fails to properly sanitize file path components, particularly when processing filenames containing forward slashes and backslashes. The vulnerability operates through a method that strips path information but does not adequately handle the conversion of forward slashes to backslashes on Windows systems, creating a pathway for malicious file placement.
The technical implementation of this vulnerability exploits the inconsistent handling of directory separators between Unix-like and Windows operating systems. When processing a filename such as /..\..\webapps\shell.war, the system removes the initial forward slash but retains backslashes that appear later in the string. This results in a path that, when processed on Windows, becomes ..\..\webapps\shell.war, effectively traversing up the directory structure and placing the malicious file in the web applications directory. The vulnerability is particularly dangerous because it leverages the Windows-specific behavior of backslash handling while the input originates from a forward slash format, creating a subtle but exploitable condition. This flaw aligns with CWE-22 Path Traversal and CWE-73 Improper Neutralization of Special Elements in File Names or Paths, both of which are fundamental security concerns in file system operations.
The operational impact of this vulnerability extends beyond simple file upload manipulation, creating a complete remote code execution vector that allows attackers to deploy malicious web applications to target servers. An attacker can leverage this vulnerability to upload WAR files or other executable web applications to the Tomcat server's webapps directory, effectively gaining persistent access to the server environment. The vulnerability's exploitation requires no special privileges beyond basic access to the FileUpload component, making it particularly dangerous in environments where file upload functionality is exposed to untrusted users. The attack chain follows typical remote code execution patterns, beginning with the initial file upload and culminating in application execution, which can be mapped to ATT&CK technique T1190 Exploit Public-Facing Application and T1059 Command and Scripting Interpreter. The vulnerability's impact is amplified in web server environments where uploaded files can be directly executed, potentially leading to complete server compromise and data exfiltration.
Organizations affected by this vulnerability should immediately implement mitigations including upgrading to patched versions of Eclipse RAP, implementing strict input validation for file upload operations, and deploying web application firewalls to monitor and filter suspicious file path patterns. The recommended solution involves ensuring that all file path components are properly sanitized regardless of the operating system, with particular attention to handling directory separators consistently across platforms. Security measures should include implementing proper file name validation that rejects any path traversal attempts, regardless of the separator type used in the input. Additionally, organizations should consider implementing principle of least privilege for file upload functionality, restricting upload capabilities to authenticated users with appropriate permissions and monitoring file upload operations for suspicious patterns. The vulnerability demonstrates the critical importance of cross-platform security considerations in file handling operations, particularly when dealing with different operating system path conventions and the potential for exploitation through seemingly benign input validation flaws.