CVE-2015-1771 in Exchange Server
Summary
by MITRE
Cross-site request forgery (CSRF) vulnerability in the web applications in Microsoft Exchange Server 2013 SP1 and Cumulative Update 8 allows remote attackers to hijack the authentication of arbitrary users, aka "Exchange Cross-Site Request Forgery Vulnerability."
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Analysis
by VulDB Data Team • 05/20/2022
The CVE-2015-1771 vulnerability represents a critical cross-site request forgery flaw that affected Microsoft Exchange Server 2013 SP1 and Cumulative Update 8 environments. This vulnerability resides within the web application components of Exchange Server, specifically targeting the authentication mechanisms that govern user sessions and access controls. The flaw enables remote attackers to manipulate authenticated sessions by tricking users into executing unauthorized actions through malicious web requests. Such vulnerabilities are particularly dangerous in enterprise environments where Exchange servers handle sensitive email communications and corporate data access. The vulnerability's impact extends beyond simple authentication bypass to potentially enable full system compromise when combined with other exploitation techniques.
The technical implementation of this CSRF vulnerability stems from insufficient validation of origin requests within the Exchange Server web interface. When users access Exchange web applications, the system relies on session cookies and authentication tokens to maintain user state. However, the flaw allows attackers to craft malicious web pages or emails that can trigger authenticated requests to the Exchange server without user knowledge or consent. The vulnerability specifically affects the web-based management interfaces and Outlook Web App functionality where user authentication is maintained through browser sessions. Attackers can leverage this weakness to perform actions such as sending emails, modifying user accounts, accessing confidential data, or altering system configurations. This flaw aligns with CWE-352, which categorizes cross-site request forgery vulnerabilities as those that permit unauthorized commands from a user that the web application believes to be legitimate.
The operational impact of CVE-2015-1771 is substantial for organizations relying on Exchange Server 2013 environments. Successful exploitation can lead to complete compromise of user accounts and potentially the entire Exchange infrastructure. Attackers can leverage this vulnerability to conduct persistent surveillance, exfiltrate sensitive email communications, and establish backdoor access points within corporate networks. The vulnerability is particularly concerning because it operates at the application layer and can be exploited through social engineering campaigns targeting end users. Organizations may experience unauthorized access to confidential business communications, data breaches, and potential compliance violations. The attack surface is broad since Exchange servers typically serve as central points for email communication and collaboration services, making them attractive targets for cybercriminals. According to ATT&CK framework, this vulnerability maps to T1566 (Phishing) and T1078 (Valid Accounts) techniques, as attackers can use the CSRF flaw to hijack legitimate user sessions and maintain persistent access.
Mitigation strategies for CVE-2015-1771 primarily involve applying Microsoft security updates and implementing additional protective measures. Microsoft released cumulative updates addressing this vulnerability, and organizations should immediately deploy the appropriate patches to remediate the issue. Beyond patching, network administrators should implement proper CSRF protection mechanisms such as anti-CSRF tokens in web forms and request validation. Organizations should also consider implementing additional security controls including web application firewalls, monitoring for suspicious authentication patterns, and user education programs to reduce social engineering risks. The vulnerability demonstrates the importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that protect against multiple attack vectors. Security teams should conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in other web applications and systems within their infrastructure.