CVE-2023-21571 in Dynamics 365
Summary
by MITRE • 02/14/2023
Microsoft Dynamics 365 (on-premises) Cross-site Scripting Vulnerability
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Analysis
by VulDB Data Team • 03/15/2023
Microsoft Dynamics 365 on-premises installations contain a cross-site scripting vulnerability that allows remote attackers to inject malicious scripts into web applications through improperly validated user input. This vulnerability specifically affects the web interface components of the on-premises deployment model, where user-supplied data is not adequately sanitized before being rendered in web pages. The flaw exists in the input validation mechanisms that fail to properly filter or escape special characters in user-provided content, creating opportunities for attackers to execute arbitrary JavaScript code within the context of authenticated users' browsers. This vulnerability falls under the CWE-79 category of Cross-site Scripting, which represents one of the most prevalent and dangerous web application security flaws in the industry. The attack vector typically involves sending malicious payloads through form fields, URL parameters, or API endpoints that are processed by the Dynamics 365 web interface. When authenticated users interact with the vulnerable application, the malicious scripts execute in their browser context, potentially leading to session hijacking, data theft, or further exploitation. The vulnerability is particularly concerning in on-premises deployments where organizations may have less frequent security updates compared to cloud environments, and where network segmentation may not adequately isolate the application from potential attack vectors. Attackers can leverage this vulnerability to perform persistent XSS attacks that can remain undetected for extended periods, especially when the malicious content is stored in application databases and displayed in user interfaces. The operational impact extends beyond simple script execution, as successful exploitation could enable attackers to access sensitive business data, modify records, or even escalate privileges within the Dynamics 365 environment. Organizations using on-premises Dynamics 365 deployments face significant risk due to the potential for attackers to gain unauthorized access to customer records, financial data, and other sensitive business information. The vulnerability aligns with ATT&CK technique T1531 which involves using malicious code to gain access to systems, and T1059 which covers command and scripting interpreter techniques. The affected components typically include the web forms, report viewers, and user interface elements that render user input without proper sanitization. Microsoft has released patches addressing this vulnerability, and organizations should prioritize applying these updates to mitigate the risk. Additionally, implementing proper input validation, output encoding, and Content Security Policy headers can provide additional layers of protection against similar vulnerabilities. Network monitoring and web application firewalls may also help detect and prevent exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for comprehensive security testing of all user-facing interfaces, particularly in enterprise applications where data sensitivity and business impact are high. Organizations should conduct regular security assessments of their on-premises deployments to identify and remediate similar vulnerabilities before they can be exploited by threat actors.