CVE-2020-17017 in SharePoint Server
Summary
by MITRE • 11/11/2020
Microsoft SharePoint Information Disclosure Vulnerability This CVE ID is unique from CVE-2020-16979.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/05/2020
Microsoft SharePoint Server contains a vulnerability that could allow an authenticated attacker to disclose information from the server. The vulnerability arises from improper validation of user-supplied input within the SharePoint server's authentication and authorization mechanisms. An attacker who successfully exploits this vulnerability could potentially access sensitive information that should be restricted to authorized users only, including but not limited to configuration details, user credentials, and internal system data. This information disclosure could enable further exploitation attempts or provide attackers with valuable insights for targeting other systems within the network infrastructure.
The technical flaw stems from insufficient input validation within SharePoint's authentication pipeline where user-provided data is not properly sanitized before being processed by the server's internal components. This weakness allows an authenticated user to craft specific requests that bypass normal access controls and retrieve information that would typically be restricted. The vulnerability specifically affects SharePoint Server 2016 and SharePoint Server 2019 versions, with the issue manifesting when the server processes certain API calls or web service requests that involve user authentication tokens or session management components. According to CWE-20, this vulnerability maps to improper input validation, a fundamental weakness that has been consistently identified as a critical security concern in enterprise web applications.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates opportunities for privilege escalation and lateral movement within affected environments. Attackers could leverage the disclosed information to craft more sophisticated attacks against other systems or to establish persistent access within the network. The vulnerability affects organizations that rely heavily on SharePoint for document management, collaboration, and intranet services, potentially exposing sensitive corporate data including employee records, business strategies, financial information, and intellectual property. Organizations using SharePoint Server 2016 and 2019 versions are particularly at risk, as these platforms have been widely deployed in enterprise environments where the confidentiality of shared resources is paramount.
Microsoft has addressed this vulnerability through security updates that include enhanced input validation mechanisms and improved access control enforcement within SharePoint Server's authentication framework. Organizations should prioritize applying the relevant security patches to mitigate this risk effectively. The mitigation strategy involves not only installing the recommended updates but also implementing additional security controls such as network segmentation, monitoring for suspicious authentication patterns, and regular security assessments of SharePoint environments. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as credential access and privilege escalation, where the initial information disclosure serves as a foundation for more advanced attack vectors. Security teams should also consider implementing application-level firewalls and monitoring solutions that can detect anomalous authentication requests that might indicate exploitation attempts. The vulnerability underscores the critical importance of maintaining up-to-date security controls and implementing defense-in-depth strategies to protect enterprise collaboration platforms from sophisticated attack techniques.