CVE-2024-51743 in Markus
Summary
by MITRE • 11/18/2024
MarkUs is a web application for the submission and grading of student assignments. In versions prior to 2.4.8, an arbitrary file write vulnerability in the update/upload/create file methods in Controllers allows authenticated instructors to write arbitrary files to any location on the web server MarkUs is running on (depending on the permissions of the underlying filesystem). e.g. This can lead to a delayed remote code execution in case an attacker is able to write a Ruby file into the config/initializers/ subfolder of the Ruby on Rails application. MarkUs v2.4.8 has addressed this issue. No known workarounds are available at the application level aside from upgrading.
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Analysis
by VulDB Data Team • 09/04/2025
The vulnerability identified as CVE-2024-51743 represents a critical arbitrary file write flaw within the MarkUs web application platform, which serves as a comprehensive system for student assignment submission and grading. This security weakness exists in versions prior to 2.4.8 and stems from insufficient input validation and sanitization within the application's file handling mechanisms. The vulnerability specifically affects the update, upload, and create file methods located within the Controllers component of the application architecture, creating a pathway for authenticated users to manipulate the file system directly through the web interface. The flaw's severity is amplified by the fact that it operates within the context of authenticated instructors, who possess legitimate access rights to the system but can exploit this vulnerability to escalate their privileges and compromise the underlying infrastructure.
The technical exploitation of this vulnerability occurs through the manipulation of file creation and upload parameters that are processed by the MarkUs application's controller methods. When an authenticated instructor performs operations related to file management, the application fails to properly validate the destination paths and file names, allowing malicious input to bypass normal security checks. This flaw enables attackers to specify arbitrary file paths on the web server's filesystem, potentially writing files to critical directories such as the config/initializers/ subfolder of the Ruby on Rails application. The specific targeting of the config/initializers/ directory is particularly concerning because this location in Ruby on Rails applications is designed for loading initialization code, making it an ideal location for persistent backdoor deployment. When a Ruby file is successfully written to this directory, it gets automatically executed during the application's startup process, creating a persistent remote code execution vector that can remain active even after system restarts.
The operational impact of CVE-2024-51743 extends far beyond simple unauthorized file creation, as it fundamentally compromises the integrity and confidentiality of the MarkUs environment. Attackers who successfully exploit this vulnerability can establish persistent access to the web server, potentially gaining control over student data, assignment submissions, and system resources. The delayed remote code execution capability means that the attack may not be immediately apparent, allowing the malicious actor to maintain access while continuing to monitor and manipulate the system. This vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and represents a classic case of path traversal vulnerability that has been exacerbated by inadequate input validation. The attack vector follows patterns consistent with ATT&CK technique T1059.006 for execution through Ruby scripts, and T1078 for valid accounts and legitimate credentials abuse.
The remediation approach for this vulnerability is straightforward yet critical for maintaining system security, requiring immediate upgrade to MarkUs version 2.4.8 or later, which contains the necessary patches to address the file handling validation issues. The vulnerability's nature makes it particularly difficult to mitigate through alternative workarounds, as the core issue lies within the application's fundamental file system interaction mechanisms rather than configuration settings or network-level protections. Organizations using MarkUs must prioritize this upgrade to prevent potential exploitation, as no application-level workarounds exist that can effectively address the underlying validation flaws in the controller methods. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web application development, where even authenticated users should not be granted unrestricted file system access through the application interface. Security teams should also implement monitoring for unusual file creation patterns in critical directories and consider implementing additional access controls and file system permissions to limit the potential impact of such vulnerabilities even if they are not immediately patched.