CVE-2016-0030 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, and 2016 allows remote attackers to inject arbitrary web script or HTML via a crafted URL, aka "Exchange Spoofing Vulnerability."
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 06/21/2018
The CVE-2016-0030 vulnerability represents a critical cross-site scripting flaw within Microsoft Exchange Server's Outlook Web Access component, specifically affecting versions including Exchange Server 2013 with Service Pack 1, Cumulative Update 10, and Exchange Server 2016. This vulnerability stems from insufficient input validation mechanisms within the OWA interface that fails to properly sanitize user-supplied URL parameters before processing them in the web application context. The flaw enables remote attackers to craft malicious URLs containing malicious script payloads that can be executed within the context of authenticated user sessions, creating a significant security risk for enterprise email environments where users regularly access Exchange services through web browsers.
The technical implementation of this vulnerability occurs when OWA processes URL parameters without adequate sanitization or encoding, allowing malicious input to be rendered as executable JavaScript within the victim's browser session. Attackers can construct specially crafted URLs that contain script code within URL parameters, which when clicked by an authenticated user would execute in the context of the victim's OWA session. This creates a persistent threat vector where attackers can leverage the trust relationship between the user and the Exchange server to execute arbitrary code, potentially accessing sensitive email content, modifying user permissions, or establishing further attack vectors within the corporate network. The vulnerability specifically affects the authentication context of OWA, where legitimate users are authenticated but malicious scripts can execute with their privileges, making it particularly dangerous for enterprise environments.
The operational impact of this vulnerability extends beyond simple script execution, as it enables sophisticated attack patterns that can compromise entire email infrastructures. Attackers can use this vulnerability to perform session hijacking, steal authentication tokens, access confidential email communications, or even escalate privileges within the Exchange environment. The spoofing nature of the vulnerability means that attackers can manipulate the user interface to display fraudulent content, potentially leading to social engineering attacks that exploit user trust in legitimate Exchange interfaces. According to CWE classification, this represents a classic cross-site scripting vulnerability categorized under CWE-79, which specifically addresses the improper neutralization of input during web page generation. The vulnerability also maps to ATT&CK technique T1566.001, which covers spearphishing with attachments, as attackers can craft malicious URLs that appear legitimate within the Exchange interface.
Mitigation strategies for CVE-2016-0030 require immediate implementation of Microsoft security patches and updates to affected Exchange Server versions, as the vulnerability was addressed through official cumulative updates that introduced proper input validation and sanitization mechanisms. Organizations should implement comprehensive URL filtering and content security policies that prevent execution of untrusted script content within the OWA environment. Network-level protections including web application firewalls and deep packet inspection can help detect and block malicious URL patterns, while user education programs should emphasize the importance of verifying URL authenticity before clicking on suspicious links. Additionally, implementing strict browser security policies such as disabling script execution for internal corporate resources and deploying content security policy headers can provide additional defense layers. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for regular security updates and vulnerability assessments in enterprise email systems, particularly those handling sensitive corporate communications and personal data.