CVE-2021-38366 in Sitecore
Summary
by MITRE • 08/13/2021
Sitecore through 10.1, when Update Center is enabled, allows remote authenticated users to upload arbitrary files and achieve remote code execution by visiting an uploaded .aspx file at an admin/Packages URL.
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Analysis
by VulDB Data Team • 08/18/2021
The vulnerability identified as CVE-2021-38366 represents a critical security flaw within Sitecore content management platforms through version 10.1. This issue specifically affects systems where the Update Center functionality remains enabled, creating an exploitable pathway for authenticated attackers to escalate their privileges and execute arbitrary code. The vulnerability stems from insufficient input validation and access control mechanisms within the package upload process, allowing malicious actors with valid credentials to bypass intended security restrictions.
The technical implementation of this vulnerability involves a combination of improper access controls and file upload validation weaknesses. When the Update Center is enabled, Sitecore permits authenticated users to upload package files through the administrative interface. However, the system fails to properly validate the file types being uploaded, particularly allowing the execution of aspx files that contain malicious code. This flaw enables attackers to upload a malicious .aspx file to the admin/Packages directory, which can then be executed directly through web browser access to the uploaded file path. The vulnerability is classified as a file upload vulnerability that leads to remote code execution, making it particularly dangerous in enterprise environments.
The operational impact of CVE-2021-38366 extends far beyond simple unauthorized file uploads, as it provides attackers with complete system compromise capabilities. Once an attacker successfully uploads a malicious .aspx file, they gain the ability to execute arbitrary commands on the target server with the privileges of the web application. This could enable full system takeover, data exfiltration, privilege escalation to administrative accounts, and establishment of persistent backdoors. The vulnerability affects organizations running Sitecore versions up to 10.1, making it particularly concerning for enterprises that may not have updated their systems. This issue directly maps to CWE-434, which describes insecure file upload vulnerabilities, and aligns with ATT&CK technique T1190 for Exploit Public-Facing Application, and T1059 for Command and Scripting Interpreter.
Organizations should immediately implement mitigations including disabling the Update Center functionality when not actively required, implementing strict file type validation on all uploaded packages, and restricting access to the admin/Packages URL endpoints. Network segmentation and web application firewalls should be configured to monitor and block suspicious file upload attempts. Additionally, organizations should enforce principle of least privilege access controls, ensuring that only authorized administrators can access package management interfaces. Regular security audits should verify that no malicious files have been uploaded to package directories, and that proper input validation is in place for all file upload mechanisms. Patch management processes should be prioritized to upgrade to Sitecore versions that have addressed this vulnerability, as the flaw represents a significant risk to enterprise security infrastructure.