CVE-2020-16979 in SharePoint Server
Summary
by MITRE • 11/11/2020
Microsoft SharePoint Information Disclosure Vulnerability This CVE ID is unique from CVE-2020-17017.
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Analysis
by VulDB Data Team • 12/05/2020
Microsoft SharePoint Server contains a vulnerability that could allow an authenticated attacker to access sensitive information through a directory traversal attack. The flaw exists in the way SharePoint handles file paths during certain operations, specifically when processing user-supplied input that is not properly validated or sanitized. This vulnerability is classified as an information disclosure issue where an attacker with valid credentials can potentially access files and directories outside of their intended scope, bypassing normal access controls and permissions mechanisms.
The technical implementation of this vulnerability stems from insufficient input validation within SharePoint's file handling routines. When processing requests that involve file paths or directory navigation, the system fails to adequately sanitize user-provided parameters, allowing maliciously crafted input to manipulate the intended file access paths. This type of vulnerability falls under the CWE-22 category for Improper Limitation of a Pathname to a Restricted Directory, commonly known as path traversal or directory traversal. The vulnerability is particularly concerning because it requires only authentication to exploit, meaning that any user with valid SharePoint credentials can potentially leverage this flaw to access unauthorized content.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to the exposure of sensitive business data, configuration files, source code repositories, and other confidential information stored within SharePoint environments. Attackers could use this vulnerability to access documents, user data, system configurations, or even administrative files that should remain protected. The vulnerability affects multiple versions of Microsoft SharePoint Server, including SharePoint Server 2016 and SharePoint Server 2019, making it a widespread concern for organizations maintaining these platforms. Organizations using SharePoint Online may also be at risk if they have hybrid configurations or if the vulnerability affects their specific implementation.
Mitigation strategies should include applying the relevant Microsoft security patches released as part of the Microsoft Security Response team's patch management process. Organizations should also implement additional security controls such as network segmentation, monitoring for unusual file access patterns, and regular security assessments of SharePoint environments. The vulnerability aligns with ATT&CK technique T1213.002 for Data from Information Repositories, which describes methods for extracting data from repositories. Security teams should also consider implementing Web Application Firewall rules to detect and block suspicious path traversal attempts, while maintaining comprehensive audit logs to track potential exploitation attempts. Regular security awareness training for SharePoint administrators and users can also help reduce the risk of successful exploitation through social engineering or credential compromise attacks.