CVE-2023-0670 in Ulearn
Summary
by MITRE • 04/05/2023
Ulearn version a5a7ca20de859051ea0470542844980a66dfc05d allows an attacker with administrator permissions to obtain remote code execution on the server through the image upload functionality. This occurs because the application does not validate that the uploaded image is actually an image.
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Analysis
by VulDB Data Team • 07/12/2025
The vulnerability identified as CVE-2023-0670 affects the Ulearn learning management system at commit a5a7ca20de859051ea0470542844980a66dfc05d, presenting a critical security risk that enables remote code execution when an attacker possesses administrator credentials. This flaw stems from insufficient input validation within the image upload functionality, creating a pathway for malicious code execution that directly compromises the server's integrity and security posture.
The technical implementation of this vulnerability resides in the application's failure to properly validate file types during the image upload process. Specifically, the system does not perform adequate checks to verify that uploaded files are legitimate image files, allowing attackers to bypass security controls by uploading malicious files that masquerade as images. This validation gap represents a classic security misconfiguration that aligns with CWE-434, which addresses insecure file upload vulnerabilities where applications fail to validate file types and contents. The vulnerability's exploitation pathway demonstrates how an attacker with administrative privileges can leverage this weakness to execute arbitrary code on the target server, effectively gaining complete control over the system's operations and data.
From an operational perspective, the impact of CVE-2023-0670 extends beyond simple privilege escalation to encompass full system compromise and potential data breaches. The vulnerability enables attackers to deploy web shells, execute malicious payloads, and establish persistent access to the compromised environment. This threat model aligns with ATT&CK technique T1505.003, which covers server-side include attacks and file execution through web shells. The remote code execution capability means that attackers can manipulate the application's behavior, exfiltrate sensitive data, and potentially use the compromised server as a launching point for further attacks within the network infrastructure. The administrative access requirement for exploitation actually makes this vulnerability more dangerous as it represents a privilege escalation issue within an already compromised administrative account.
Mitigation strategies for CVE-2023-0670 must address both the immediate validation gap and broader security practices. Organizations should implement comprehensive file type validation that includes MIME type checking, file signature verification, and content analysis to ensure uploaded files are genuine image files. The solution should incorporate proper file extension validation, enforce strict file content verification, and implement secure file storage practices that separate uploaded files from executable code. Additionally, organizations should enforce principle of least privilege, implement multi-factor authentication for administrative accounts, and conduct regular security assessments to identify similar validation vulnerabilities across the application stack. The fix should align with security best practices outlined in OWASP Top 10 and NIST cybersecurity frameworks, specifically addressing the prevention of file upload vulnerabilities and ensuring proper input sanitization. Regular updates and patch management procedures should be established to prevent similar issues from arising in future versions of the application, while also implementing network monitoring and intrusion detection systems to identify potential exploitation attempts.