CVE-2018-0799 in SharePoint Enterprise Server
Summary
by MITRE
Microsoft Access in Microsoft SharePoint Enterprise Server 2013 and Microsoft SharePoint Enterprise Server 2016 allows a cross-site-scripting (XSS) vulnerability due to the way image field values are handled, aka "Microsoft Access Tampering Vulnerability".
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Analysis
by VulDB Data Team • 01/29/2021
The Microsoft Access Tampering Vulnerability identified as CVE-2018-0799 represents a critical cross-site scripting flaw within Microsoft SharePoint Enterprise Server 2013 and 2016 platforms. This vulnerability stems from improper handling of image field values in the Microsoft Access integration component, creating an avenue for malicious actors to inject arbitrary script code into web applications. The flaw specifically manifests when SharePoint servers process image field data from Microsoft Access databases, allowing attackers to manipulate the data handling process and execute malicious scripts in the context of the victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of image field values that are processed by SharePoint's Access integration functionality. When users interact with SharePoint lists or libraries that contain image fields sourced from Microsoft Access databases, the application fails to properly sanitize or validate the image metadata before rendering it in web pages. This inadequate input validation creates a persistent cross-site scripting vector where attacker-controlled data can be executed as script code within the victim's browser environment. The vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications, and aligns with ATT&CK technique T1059.007 for scripting languages and T1566 for phishing with malicious attachments or links.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform session hijacking, data exfiltration, and privilege escalation within the SharePoint environment. An attacker who successfully exploits this vulnerability could gain access to sensitive information stored within SharePoint, manipulate user sessions, and potentially move laterally within the network infrastructure. The vulnerability is particularly concerning because SharePoint servers often contain sensitive business data, user credentials, and organizational information that could be compromised. Additionally, the attack surface is broad as any user with access to SharePoint lists or libraries containing image fields from Microsoft Access databases could be targeted.
Organizations should implement multiple layers of defense to mitigate this vulnerability effectively. Immediate remediation requires applying Microsoft's security patches and updates specifically addressing CVE-2018-0799, which should be prioritized in all production environments. Network segmentation and web application firewall deployment can provide additional protection by monitoring and filtering malicious script payloads before they reach vulnerable SharePoint servers. Input validation and output encoding should be strengthened throughout the SharePoint application stack, particularly for all image field processing components. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other Microsoft Access integration components. The implementation of strict content security policies and regular monitoring of user activities within SharePoint environments will help detect potential exploitation attempts and provide early warning of security incidents. Organizations should also consider restricting user permissions and implementing least privilege access controls to minimize the potential impact of successful exploitation.