CVE-2021-28478 in SharePoint Server
Summary
by MITRE • 05/12/2021
Microsoft SharePoint Spoofing Vulnerability This CVE ID is unique from CVE-2021-26418, CVE-2021-31172.
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Analysis
by VulDB Data Team • 03/01/2025
Microsoft SharePoint contains a spoofing vulnerability that allows attackers to manipulate the user interface of the platform in ways that can deceive users into believing they are interacting with legitimate system components. This vulnerability specifically affects the way SharePoint handles certain user interface elements and can be exploited to create misleading visual representations of system functionality. The flaw stems from insufficient validation of user interface components within the SharePoint framework, particularly in how the system renders certain elements that users interact with during normal operations.
The technical implementation of this vulnerability involves the manipulation of SharePoint's rendering engine to present forged content that appears authentic to end users. Attackers can exploit this weakness by crafting malicious content that exploits the insufficient validation mechanisms in place. The vulnerability exists primarily in the client-side rendering processes where SharePoint displays various interface components including but not limited to navigation elements, status indicators, and contextual menus. This allows threat actors to potentially redirect users to malicious sites or present false information that could be used for social engineering attacks.
From an operational perspective, this vulnerability poses significant risks to organizations relying on SharePoint for business operations. The spoofing capability can be leveraged to create convincing phishing attacks that target SharePoint users, potentially leading to credential theft or unauthorized access to sensitive organizational data. The impact extends beyond simple deception as attackers can use this vulnerability to manipulate user workflows and potentially escalate privileges within the SharePoint environment. The vulnerability affects multiple versions of SharePoint Server and SharePoint Online, making it a widespread concern for organizations maintaining these platforms.
The exploitation of this vulnerability aligns with several tactics outlined in the attack framework, particularly those involving user interface manipulation and social engineering. This type of attack maps to the technique of credential access through deception, where attackers leverage the trust users place in familiar interface elements. Organizations should consider implementing additional security controls beyond standard SharePoint hardening measures, including enhanced monitoring of user interface rendering behaviors and regular security assessments of SharePoint environments. The vulnerability also highlights the importance of maintaining up-to-date security patches and following the principle of least privilege when configuring SharePoint access controls.
Security professionals should note that this vulnerability demonstrates the critical importance of validating all user interface components within web applications. The issue relates to common weakness identifiers such as CWE-601 and CWE-79, which address URL redirection and cross-site scripting vulnerabilities respectively. Organizations should implement comprehensive security monitoring solutions that can detect anomalous interface rendering patterns and establish incident response procedures specifically tailored to address spoofing attacks. Regular security training for SharePoint administrators and end users can also help mitigate the risk associated with this type of deception attack.
Mitigation strategies should include applying the latest security patches released by Microsoft, implementing network segmentation to limit access to SharePoint environments, and establishing robust monitoring procedures for unusual interface behavior. Organizations should also consider implementing additional authentication controls such as multi-factor authentication and regularly reviewing access permissions within SharePoint to ensure that only authorized users can modify interface elements. The vulnerability underscores the necessity of maintaining a defense-in-depth strategy that includes both technical controls and user awareness training to protect against sophisticated spoofing attacks that exploit the trust users place in familiar system interfaces.