CVE-2018-8300 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 affects Microsoft SharePoint.
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Analysis
by VulDB Data Team • 04/05/2023
The vulnerability identified as CVE-2018-8300 represents a critical remote code execution flaw within Microsoft SharePoint software systems. This weakness stems from insufficient validation of source markup within application packages, creating an exploitable condition that allows attackers to execute arbitrary code on affected systems. The vulnerability specifically impacts Microsoft SharePoint Server versions including 2013, 2016, and 2019, making it a widespread concern across enterprise environments that rely on SharePoint for document management and collaboration services. The flaw exists at the application package validation layer where SharePoint fails to properly sanitize or verify the integrity of markup content within packages that are uploaded or deployed to the platform.
From a technical perspective, this vulnerability operates through a markup validation bypass mechanism that allows malicious actors to embed malicious code within legitimate-looking SharePoint application packages. The issue manifests when SharePoint processes these packages without adequate source verification, enabling attackers to inject harmful payloads that can execute with the privileges of the SharePoint service account. This particular flaw aligns with CWE-20, which describes improper input validation, and represents a classic example of a code injection vulnerability that can be exploited remotely. The vulnerability can be triggered through the SharePoint app installation process, where users or administrators upload packages that contain malicious markup elements designed to bypass normal security checks.
The operational impact of CVE-2018-8300 extends beyond simple remote code execution capabilities, as it provides attackers with persistent access to affected SharePoint environments. Successful exploitation can lead to complete system compromise, data exfiltration, and lateral movement within corporate networks where SharePoint servers serve as central collaboration platforms. Organizations utilizing SharePoint for sensitive document management, workflow automation, and enterprise collaboration face significant risk from this vulnerability, as it can be exploited without user interaction and requires minimal privileges to execute. The attack vector typically involves uploading a malicious SharePoint package through the standard app installation interface, which then executes the embedded payload when SharePoint processes the package contents. This vulnerability particularly affects organizations that have SharePoint servers configured to allow user app installations or that maintain default configurations without proper security hardening.
Mitigation strategies for CVE-2018-8300 should prioritize immediate implementation of Microsoft security patches and updates released in response to this vulnerability. Organizations must ensure their SharePoint environments are updated with the latest security patches, particularly focusing on the specific versions mentioned in the vulnerability description. Network segmentation and access controls should be implemented to limit exposure of SharePoint servers to untrusted networks, while monitoring solutions should be configured to detect unusual package upload activities or suspicious markup content. Security professionals should also consider implementing application whitelisting policies that restrict the execution of unsigned or untrusted SharePoint packages, and establish regular vulnerability scanning procedures to identify potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1203, which describes Exploitation for Client Execution, highlighting the importance of endpoint protection and application control measures. Additionally, organizations should conduct comprehensive security assessments of their SharePoint configurations to identify and remediate any misconfigurations that could exacerbate the vulnerability's impact, including reviewing permissions and access controls for app installation capabilities.