CVE-2022-41955 in Autolab
Summary
by MITRE • 01/14/2023
Autolab is a course management service, initially developed by a team of students at Carnegie Mellon University, that enables instructors to offer autograded programming assignments to their students over the Web. A remote code execution vulnerability was discovered in Autolab's MOSS functionality, whereby an instructor with access to the feature might be able to execute code on the server hosting Autolab. This vulnerability has been patched in version 2.10.0. As a workaround, disable the MOSS feature if it is unneeded by replacing the body of `run_moss` in `app/controllers/courses_controller.rb` with `render(plain: "Feature disabled", status: :bad_request) && return`.
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Analysis
by VulDB Data Team • 01/14/2023
The CVE-2022-41955 vulnerability represents a critical remote code execution flaw within Autolab's MOSS (Measure Of Software Similarity) functionality, which is a plagiarism detection tool commonly used in academic settings. This vulnerability specifically targets the course management service Autolab that was originally developed by Carnegie Mellon University's students and is widely adopted by educational institutions for managing programming assignments with automated grading capabilities. The MOSS feature enables instructors to compare student submissions against each other and against external sources to detect potential plagiarism, making it an integral part of the academic integrity framework within these platforms.
The technical flaw stems from inadequate input validation and sanitization within the MOSS execution process, allowing an authenticated instructor with access to the MOSS functionality to inject malicious code that gets executed on the server hosting the Autolab platform. This type of vulnerability falls under the Common Weakness Enumeration category CWE-74, which describes "Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')", specifically manifesting as a code injection vulnerability within a web application context. The vulnerability is particularly dangerous because it leverages legitimate administrative privileges to achieve unauthorized code execution on the server, bypassing traditional network-level security controls.
The operational impact of this vulnerability is severe for educational institutions relying on Autolab for their programming course management. An attacker with instructor-level access could potentially compromise the entire server infrastructure, leading to data breaches, unauthorized access to student information, and potential disruption of academic services. The attack vector requires only an authenticated user with MOSS access, which is often granted to instructors and teaching assistants, making the attack surface relatively broad within academic environments. This vulnerability could enable attackers to escalate privileges, access sensitive academic data, or even use the compromised server as a launchpad for further attacks within the institution's network infrastructure.
The vulnerability has been addressed through patching in version 2.10.0 of Autolab, which implements proper input validation and sanitization measures to prevent code injection attacks. Organizations that cannot immediately upgrade should implement the recommended workaround of disabling the MOSS feature entirely by modifying the run_moss method in the courses_controller.rb file to return a bad request status with a plain text response. This mitigation strategy aligns with the principle of least privilege and follows the ATT&CK framework's recommendation for disabling or removing features that are not essential to operations. The vulnerability demonstrates the importance of secure coding practices, particularly in web applications that handle user input, and underscores the need for regular security assessments and timely patch management in educational technology platforms.