CVE-2016-0032 in Exchange Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Outlook Web Access (OWA) in Microsoft Exchange Server 2013 PS1, 2013 Cumulative Update 10, 2013 Cumulative Update 11, and 2016 allows remote attackers to inject arbitrary web script or HTML via a crafted URL, aka "Exchange Spoofing Vulnerability."
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Analysis
by VulDB Data Team • 06/21/2018
The CVE-2016-0032 vulnerability represents a critical cross-site scripting flaw discovered in Microsoft Exchange Server's Outlook Web Access component, specifically affecting versions including Exchange Server 2013 with Service Pack 1 and Cumulative Updates 10 and 11, as well as Exchange Server 2016. This vulnerability operates under the broader category of CWE-79 Improper Neutralization of Input During Web Page Generation, which classifies it as a web application security weakness where user-supplied data is not properly sanitized before being rendered in web pages. The flaw enables remote attackers to execute malicious scripts within the context of a victim's browser session, exploiting the trust relationship between the user and the targeted Exchange server.
The technical mechanism behind this vulnerability involves the improper handling of URL parameters within the Outlook Web Access interface, where crafted malicious URLs can contain embedded script code that gets executed when the page loads. Attackers can construct specially formatted URLs that appear legitimate to users but contain hidden malicious payloads, allowing them to bypass standard security controls. The vulnerability specifically affects the spoofing capabilities within Exchange OWA, enabling attackers to manipulate the display of content in a way that can deceive users into executing malicious code. This type of attack falls under the ATT&CK technique T1566.001 Phishing, as it exploits user trust and can lead to credential theft, session hijacking, or further exploitation of the compromised system.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal authentication tokens, and potentially gain access to sensitive email communications and user data. The vulnerability's remote exploitation capability means that attackers do not require local access to the server, making it particularly dangerous for organizations with Exchange servers exposed to the internet. The spoofing nature of the vulnerability allows attackers to create convincing fake login pages or manipulate existing web interfaces to capture user credentials. Organizations may experience significant disruption to their email services and potential data breaches, with the attack surface extending to all users who access Exchange through OWA. The vulnerability also impacts the integrity of the email communication system, as attackers can modify content displayed to users without detection.
Mitigation strategies for CVE-2016-0032 should include immediate application of Microsoft security patches and updates, particularly the cumulative updates for Exchange Server 2013 and 2016. Network segmentation and access controls should be implemented to limit exposure of Exchange servers to untrusted networks, while monitoring solutions should be deployed to detect suspicious URL patterns and potential exploitation attempts. Organizations should also implement additional security layers including web application firewalls, enhanced email filtering, and user education programs to recognize potential phishing attempts. The vulnerability demonstrates the importance of regular security updates and proper input validation in web applications, aligning with security best practices outlined in standards such as NIST SP 800-53 and ISO/IEC 27001. Security teams should conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in other web applications and systems within their environment.