CVE-2018-16367 in OnlineJudge
Summary
by MITRE
In OnlineJudge 2.0, the sandbox has an incorrect access control vulnerability that can write a file anywhere. A user can write a directory listing to /tmp, and can leak file data with a #include.
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Analysis
by VulDB Data Team • 05/06/2023
The vulnerability identified as CVE-2018-16367 affects OnlineJudge 2.0, a web-based platform for online programming competitions and automated grading systems. This issue resides within the sandbox implementation that is designed to isolate and contain user submissions during execution to prevent unauthorized system access. The sandbox mechanism serves as a critical security boundary that should enforce strict access controls to protect the underlying system from malicious code execution. However, a flaw in the access control implementation allows attackers to bypass these protective measures and gain unauthorized write permissions to arbitrary locations on the file system.
The technical flaw manifests as an incorrect access control vulnerability within the sandbox environment that permits unauthorized file operations. Specifically, the vulnerability enables a user to write files to any location within the system, with the described capability to write directory listings to the /tmp directory. This represents a severe privilege escalation issue where a regular user can manipulate system files outside of their intended scope. The vulnerability also allows for file data leakage through include directives, which can be exploited to read sensitive files from the system. This dual nature of the vulnerability provides both write access and information disclosure capabilities, significantly amplifying the potential impact.
The operational impact of this vulnerability is substantial as it fundamentally compromises the security model of the OnlineJudge platform. Attackers can leverage this vulnerability to write malicious files to critical system locations, potentially leading to persistent backdoors or system compromise. The ability to write directory listings to /tmp suggests that attackers can create or modify files in a temporary directory that may be accessible to other processes or users. The file data leakage capability through #include directives enables attackers to extract sensitive information from the system, potentially including source code, configuration files, or other confidential data. This vulnerability essentially undermines the sandbox isolation that should protect the system from user-submitted code.
Security mitigations for this vulnerability should focus on implementing proper access control mechanisms within the sandbox environment. The system must enforce strict file system permissions and validate all file operations performed by user submissions. Input validation and sanitization should be implemented to prevent unauthorized file operations, while proper privilege separation must be maintained between the sandboxed environment and the host system. Additionally, the include directive functionality should be restricted to prevent arbitrary file reading operations. This vulnerability aligns with CWE-284 Access Control Issues, specifically related to improper access control within sandboxed environments. From an ATT&CK perspective, this vulnerability maps to T1059 Command and Scripting Interpreter and T1078 Valid Accounts, as it allows for privilege escalation and persistent access to the system. The remediation efforts should include comprehensive security testing of the sandbox implementation, proper privilege reduction for execution environments, and implementation of proper file system access controls. Organizations using OnlineJudge 2.0 should immediately apply patches or updates that address the access control flaws in the sandbox mechanism to prevent exploitation.