CVE-2018-8518 in SharePoint Enterprise Server
Summary
by MITRE
An elevation of privilege vulnerability exists when Microsoft SharePoint Server does not properly sanitize a specially crafted web request to an affected SharePoint server, aka "Microsoft SharePoint Elevation of Privilege Vulnerability." This affects Microsoft SharePoint. This CVE ID is unique from CVE-2018-8480, CVE-2018-8488, CVE-2018-8498.
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Analysis
by VulDB Data Team • 05/23/2023
The vulnerability identified as CVE-2018-8518 represents a critical elevation of privilege flaw within Microsoft SharePoint Server that stems from inadequate input validation mechanisms. This weakness allows malicious actors to exploit specially crafted web requests that bypass normal security restrictions, enabling unauthorized users to gain higher privileges than initially granted. The vulnerability specifically affects Microsoft SharePoint Server environments where proper sanitization of web requests fails to occur, creating a pathway for privilege escalation attacks that can compromise the integrity and confidentiality of sensitive data within the SharePoint infrastructure.
Technical exploitation of this vulnerability occurs through the manipulation of web requests that are processed by SharePoint Server components. When the server receives a crafted request containing malicious input, the insufficient sanitization allows attacker-controlled data to be interpreted as legitimate commands or parameters. This flaw typically manifests in scenarios where SharePoint Server accepts user-supplied data without proper validation or encoding, enabling attackers to inject malicious elements that can be executed within the server context. The vulnerability operates at the application layer, leveraging weaknesses in the SharePoint Server's request handling mechanisms to bypass standard access controls and authentication checks.
The operational impact of CVE-2018-8518 extends beyond simple privilege escalation, potentially enabling attackers to access sensitive information, modify data, or even take complete control of affected SharePoint environments. Organizations running vulnerable SharePoint Server instances face significant risks including data breaches, unauthorized access to confidential documents, and potential lateral movement within network infrastructures. The vulnerability's impact is particularly concerning because SharePoint servers often host critical business information, user credentials, and organizational data that, once compromised, can lead to substantial financial and reputational damage. Security teams must consider that successful exploitation could result in persistent access and data exfiltration capabilities that may remain undetected for extended periods.
Mitigation strategies for CVE-2018-8518 should focus on implementing comprehensive input validation and sanitization measures across SharePoint Server environments. Organizations should prioritize applying Microsoft security patches and updates released to address this vulnerability, while also implementing network segmentation and monitoring to detect anomalous request patterns. Security controls should include enhanced web application firewall rules, proper input validation at all entry points, and regular security assessments to identify potential exploitation vectors. The vulnerability aligns with CWE-20, which describes improper input validation, and may be mapped to ATT&CK technique T1068, involving the use of elevated privileges to gain access to systems. Additionally, organizations should consider implementing principle of least privilege access controls and regular security audits to minimize the attack surface and reduce the potential impact of similar vulnerabilities in the future.