CVE-2018-8635 in SharePoint Enterprise Server
Summary
by MITRE
An elevation of privilege vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted authentication request to an affected SharePoint server, aka "Microsoft SharePoint Server Elevation of Privilege Vulnerability." This affects Microsoft SharePoint Server, Microsoft SharePoint.
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Analysis
by VulDB Data Team • 06/18/2023
The vulnerability identified as CVE-2018-8635 represents a critical elevation of privilege flaw within Microsoft SharePoint Server environments that stems from inadequate input validation during authentication request processing. This weakness allows attackers to exploit the system's failure to properly sanitize authentication requests, potentially enabling unauthorized users to escalate their privileges and gain elevated access rights within the SharePoint infrastructure. The vulnerability specifically targets the authentication handling mechanisms of SharePoint Server, which serves as a cornerstone for enterprise collaboration and document management platforms.
From a technical perspective, the flaw manifests when SharePoint Server processes authentication requests that contain maliciously crafted parameters or headers that bypass normal validation checks. The system fails to adequately sanitize user inputs during the authentication flow, creating a pathway for attackers to manipulate the authentication process and assume the identity of other users or gain administrative privileges. This type of vulnerability falls under CWE-20, which encompasses improper input validation, and represents a classic example of how insufficient sanitization of user-supplied data can lead to privilege escalation attacks. The vulnerability's impact is particularly severe given SharePoint's role as a central enterprise collaboration platform where administrative access can provide extensive control over organizational data and systems.
The operational impact of CVE-2018-8635 extends far beyond simple privilege escalation, as successful exploitation can enable attackers to access sensitive corporate data, modify or delete critical documents, manipulate user permissions, and potentially establish persistent access within the SharePoint environment. Organizations utilizing SharePoint Server are particularly vulnerable because the flaw can be exploited remotely without requiring prior authentication, making it an attractive target for attackers seeking to gain unauthorized access to enterprise collaboration platforms. The vulnerability affects multiple versions of Microsoft SharePoint Server, including 2016 and 2019 editions, and can be leveraged to compromise entire SharePoint deployments. This type of attack vector aligns with ATT&CK technique T1078 which covers valid accounts and credential access, as the exploitation involves legitimate authentication mechanisms that are being misused rather than brute force attacks against authentication systems.
Mitigation strategies for CVE-2018-8635 should prioritize immediate application of Microsoft's security patches and updates, which address the underlying input sanitization issues in the authentication handling components. Organizations should implement network segmentation to limit access to SharePoint servers and establish robust monitoring for unusual authentication patterns or requests that might indicate exploitation attempts. Additional protective measures include implementing strict access controls, regularly auditing user permissions, and deploying intrusion detection systems capable of identifying suspicious authentication request patterns. Security teams should also consider implementing multi-factor authentication for SharePoint access and conducting regular vulnerability assessments to identify potential exploitation vectors. The remediation process should include comprehensive testing of patches in non-production environments before deployment to ensure compatibility with existing SharePoint configurations and business applications. Organizations should also review their incident response procedures to ensure readiness for potential exploitation of this vulnerability, as the impact of successful attacks can extend beyond immediate privilege escalation to include data compromise and system integrity violations.