CVE-2015-1764 in Exchange Server
Summary
by MITRE
The web applications in Microsoft Exchange Server 2013 SP1 and Cumulative Update 8 allow remote attackers to bypass the Same Origin Policy and send HTTP traffic to intranet servers via a crafted request, related to a Server-Side Request Forgery (SSRF) issue, aka "Exchange Server-Side Request Forgery Vulnerability."
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Analysis
by VulDB Data Team • 05/20/2022
The vulnerability identified as CVE-2015-1764 represents a critical Server-Side Request Forgery (SSRF) flaw within Microsoft Exchange Server 2013 SP1 and Cumulative Update 8 web applications. This security weakness stems from insufficient validation of user-supplied input in the web interface components that handle HTTP requests, creating an avenue for malicious actors to manipulate server-side operations. The flaw specifically affects the Same Origin Policy enforcement mechanisms that are fundamental to web security, allowing attackers to circumvent normal access controls and potentially gain unauthorized access to internal network resources that would otherwise be protected by firewalls and network segmentation.
The technical implementation of this vulnerability occurs through crafted HTTP requests that exploit the web application's inability to properly validate or sanitize input parameters before forwarding requests to internal servers. When an attacker submits a maliciously crafted request through the Exchange web interface, the server processes this request without adequate validation, effectively acting as an intermediary that can make arbitrary HTTP requests to internal systems. This behavior violates the fundamental principle of web application security that prevents client-side applications from making requests to internal resources without proper authorization. The vulnerability is categorized under CWE-918, which specifically addresses Server-Side Request Forgery vulnerabilities where applications fail to validate or sanitize user input before making server-side requests.
The operational impact of CVE-2015-1764 extends far beyond simple data exfiltration, as it provides attackers with the capability to perform reconnaissance and potentially execute further attacks against internal network infrastructure. An attacker could leverage this vulnerability to scan internal network ports, access internal web services, retrieve sensitive information from internal databases, or even escalate privileges within the internal network. The vulnerability is particularly dangerous because it can be exploited remotely without requiring authentication to the Exchange server itself, making it an attractive target for automated scanning tools and malicious actors seeking to expand their attack surface. This SSRF vulnerability essentially transforms the Exchange server into a potential pivot point for internal network reconnaissance and lateral movement attacks, which aligns with techniques documented in the MITRE ATT&CK framework under the T1018 and T1046 tactics for discovery and remote service enumeration.
Mitigation strategies for CVE-2015-1764 should focus on implementing comprehensive input validation and sanitization mechanisms within the web application layer, combined with network-level restrictions that prevent internal server access. Organizations should apply the official Microsoft security updates and patches that address this specific vulnerability, while also implementing network segmentation and firewall rules that restrict internal server communication from external-facing web applications. Additional protective measures include deploying web application firewalls that can detect and block suspicious request patterns, implementing strict access controls that limit what internal resources can be accessed through the Exchange web interface, and conducting regular security assessments to identify similar vulnerabilities in other web applications. The vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing defense-in-depth strategies that protect against both known and emerging threats in enterprise email infrastructure.