CVE-2020-1023 in SharePoint Enterprise Server
Summary
by MITRE
A remote code execution vulnerability exists in Microsoft SharePoint when the software fails to check the source markup of an application package, aka 'Microsoft SharePoint Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2020-1024, CVE-2020-1102.
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Analysis
by VulDB Data Team • 10/16/2020
The vulnerability identified as CVE-2020-1023 represents a critical remote code execution flaw within Microsoft SharePoint software that stems from inadequate validation of application package source markup. This weakness allows attackers to execute arbitrary code on affected systems remotely without requiring authentication, making it particularly dangerous for enterprise environments where SharePoint servers are exposed to untrusted networks. The vulnerability specifically affects Microsoft SharePoint Server 2016 and SharePoint Server 2019 versions, with the flaw residing in the application package validation mechanism that fails to properly sanitize input from potentially malicious sources. This issue is classified under CWE-20 as "Improper Input Validation" and aligns with ATT&CK technique T1203 "Exploitation for Client Execution" which involves using vulnerabilities to execute code on target systems.
The technical exploitation of this vulnerability occurs when SharePoint processes application packages that contain malicious markup or code within their source files. Attackers can craft specially designed application packages that bypass the normal validation checks, allowing them to inject and execute arbitrary code with the privileges of the SharePoint service account. This typically involves manipulating the package manifest or embedded components to include malicious payloads that are executed during the package installation or deployment process. The vulnerability's impact extends beyond simple code execution as it can enable attackers to establish persistent access, escalate privileges, and potentially move laterally within the network environment. The flaw represents a failure in the principle of least privilege and demonstrates inadequate defense-in-depth measures within the SharePoint application packaging subsystem.
From an operational standpoint, organizations running affected SharePoint installations face significant risk exposure, particularly those with internet-facing SharePoint servers or those that allow external users to upload or deploy applications. The remote nature of the exploit means that attackers can target these systems from anywhere on the internet, making traditional network perimeter defenses insufficient. Successful exploitation can lead to complete system compromise, data exfiltration, and potential disruption of business operations. The vulnerability's classification as a remote code execution flaw places it in the highest severity category, as it enables attackers to gain full control over affected systems without requiring physical access or user interaction. Organizations may experience cascading effects including system downtime, regulatory compliance violations, and potential legal ramifications from data breaches.
Mitigation strategies for CVE-2020-1023 should prioritize immediate implementation of Microsoft security updates and patches released through the Microsoft Security Response Center. Organizations should also implement network segmentation to limit access to SharePoint servers, disable unnecessary application deployment features, and establish robust monitoring for suspicious package uploads or installations. Additional defensive measures include implementing application whitelisting policies, conducting regular security assessments of SharePoint configurations, and maintaining comprehensive incident response procedures. The vulnerability highlights the importance of secure coding practices and proper input validation as outlined in the OWASP Top Ten and ISO/IEC 27001 security standards. Organizations should also consider deploying web application firewalls and network intrusion detection systems to monitor for exploitation attempts targeting SharePoint services. Regular security training for administrators and developers regarding secure application packaging practices is essential to prevent similar vulnerabilities in custom SharePoint solutions and third-party applications.