CVE-2021-34468 in SharePoint Server
Summary
by MITRE • 07/15/2021
Microsoft SharePoint Server Remote Code Execution Vulnerability This CVE ID is unique from CVE-2021-34467, CVE-2021-34520.
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Analysis
by VulDB Data Team • 07/17/2021
Microsoft SharePoint Server contains a remote code execution vulnerability that arises from improper validation of user-supplied input within the server-side processing logic. This flaw exists in the way SharePoint handles specific data structures during content rendering and processing operations, creating an avenue for malicious actors to execute arbitrary code on affected systems. The vulnerability specifically impacts SharePoint Server 2016 and SharePoint Server 2019 installations, where the insufficient input sanitization allows attackers to craft malicious payloads that bypass security controls and gain unauthorized access to system resources.
The technical implementation of this vulnerability stems from a lack of proper validation mechanisms in the SharePoint Server's content processing pipeline. When the server receives certain crafted input parameters, it fails to adequately sanitize or validate the data before processing, leading to potential code injection scenarios. This weakness aligns with CWE-74 and CWE-79 classifications related to injection flaws and cross-site scripting vulnerabilities, respectively. The flaw operates at the application layer and requires no special privileges to exploit, making it particularly dangerous as it can be triggered through standard user interactions with SharePoint web interfaces.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to establish persistent access to SharePoint environments and potentially escalate privileges within the affected network. Successful exploitation allows threat actors to deploy malicious payloads, access sensitive data repositories, modify content, and potentially use the compromised SharePoint server as a foothold for lateral movement throughout the enterprise infrastructure. The vulnerability's remote nature means that attackers can exploit it from external networks without requiring physical access to the affected systems, creating a significant risk for organizations that do not maintain proper network segmentation.
Organizations should implement immediate mitigations including applying the relevant Microsoft security updates and patches released in June 2021 as part of the Microsoft Security Response. Network-level protections should include implementing web application firewalls to monitor and filter suspicious traffic patterns targeting SharePoint server endpoints, while also enforcing strict access controls and monitoring for unusual file uploads or content modifications. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1190 for exploiting public-facing applications and T1059 for command and script injection, highlighting the need for comprehensive security monitoring across multiple threat detection domains. Additional defensive measures should include regular security assessments of SharePoint configurations, implementation of privileged access management controls, and enhanced logging and monitoring of user activities within SharePoint environments to detect potential exploitation attempts.