CVE-2015-1629 in Exchange Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Outlook Web App (OWA) in Microsoft Exchange Server 2013 SP1 and Cumulative Update 7 allows remote attackers to inject arbitrary web script or HTML via a crafted URL, aka "ExchangeDLP Cross Site Scripting Vulnerability."
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Analysis
by VulDB Data Team • 04/15/2022
The CVE-2015-1629 vulnerability represents a critical cross-site scripting flaw discovered in Microsoft Exchange Server 2013 SP1 and Cumulative Update 7, specifically affecting Outlook Web App functionality. This vulnerability resides within the Exchange Data Loss Prevention (DLP) component that processes user input through URLs, creating an attack vector that enables remote threat actors to execute malicious scripts within the context of authenticated user sessions. The flaw manifests when the application fails to properly sanitize user-supplied URL parameters before rendering them in web responses, allowing attackers to inject arbitrary HTML and JavaScript code that executes in the victim's browser.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding mechanisms within the OWA interface. When users navigate to specially crafted URLs containing malicious payloads, the Exchange server processes these inputs without adequate sanitization, leading to the execution of injected scripts in the browser context of legitimate users who access the affected system. This particular weakness aligns with CWE-79, which categorizes cross-site scripting vulnerabilities as a result of improper neutralization of input during web page generation. The vulnerability specifically impacts the Exchange Server's handling of DLP policies and URL processing, where user-controllable parameters are directly incorporated into HTML responses without proper context-appropriate encoding.
The operational impact of CVE-2015-1629 extends beyond simple script execution, as it enables attackers to perform session hijacking, data exfiltration, and privilege escalation within the Exchange environment. Threat actors can leverage this vulnerability to steal session cookies, access sensitive email communications, and potentially gain deeper system access through the exploitation of authenticated user contexts. The attack surface is particularly concerning for enterprise environments where Exchange servers serve as primary email gateways, as successful exploitation could compromise thousands of user accounts and lead to significant data breaches. This vulnerability also maps to ATT&CK technique T1059.007 for command and control through web shells and T1566 for social engineering via malicious web content delivery.
Organizations should implement immediate mitigations including applying Microsoft's security patches and updates, implementing strict input validation controls, and deploying web application firewalls to detect and block malicious URL patterns. Network segmentation and monitoring of suspicious URL access patterns can help identify exploitation attempts. The vulnerability demonstrates the importance of proper input sanitization and output encoding practices as outlined in OWASP Top Ten security principles, particularly in enterprise web applications where user input directly influences web content generation. Regular security assessments and penetration testing should be conducted to identify similar input validation weaknesses in other applications and systems within the enterprise infrastructure.