CVE-2017-8560 in Exchange Server
Summary
by MITRE
Microsoft Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5 allows an elevation of privilege vulnerability due to the way that Exchange Outlook Web Access (OWA) handles web requests, aka "Microsoft Exchange Cross-Site Scripting Vulnerability". This CVE ID is unique from CVE-2017-8559.
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Analysis
by VulDB Data Team • 12/31/2020
The vulnerability identified as CVE-2017-8560 represents a critical elevation of privilege flaw within Microsoft Exchange Server implementations that affects multiple versions including Exchange Server 2010 SP3, Exchange Server 2013 SP3, Exchange Server 2013 CU16, and Exchange Server 2016 CU5. This security weakness specifically manifests through the handling of web requests within the Outlook Web Access component of Exchange Server, creating an avenue for malicious actors to escalate their privileges within the targeted environment. The vulnerability's classification as a cross-site scripting issue places it within the purview of CWE-79, which specifically addresses cross-site scripting vulnerabilities that allow attackers to inject malicious scripts into web applications. The flaw exploits the improper sanitization of user input within OWA's request processing pipeline, enabling attackers to execute arbitrary code with elevated privileges.
The technical exploitation of this vulnerability occurs through the manipulation of web requests that traverse the Exchange Server's OWA interface. When users interact with Outlook Web Access, the server processes incoming HTTP requests without adequate validation of input parameters, allowing malicious payloads to be injected and subsequently executed within the context of the target user's session. This particular weakness enables attackers to bypass normal authentication and authorization mechanisms, potentially gaining access to sensitive email data, administrative functions, and other privileged resources within the Exchange environment. The vulnerability's impact extends beyond simple script execution as it creates a persistent backdoor that can be leveraged for further lateral movement and privilege escalation throughout the network infrastructure.
From an operational perspective, the exploitation of CVE-2017-8560 poses significant risks to organizations relying on Microsoft Exchange Server for email services. The vulnerability can be exploited remotely without requiring authentication, making it particularly dangerous for organizations with exposed Exchange servers on the internet. Attackers can leverage this flaw to gain unauthorized access to user mailboxes, modify email content, access calendar data, and potentially escalate privileges to administrative levels within the Exchange environment. The vulnerability's presence in multiple Exchange Server versions means that organizations across different deployment scenarios face similar risks, creating widespread potential impact across enterprise email infrastructures. This weakness directly aligns with ATT&CK technique T1059, which covers the use of command and scripting interpreters for execution, as the vulnerability enables attackers to execute malicious code within the Exchange server environment.
Organizations should implement immediate mitigations including applying the relevant security patches released by Microsoft to address the identified cross-site scripting vulnerability. The patching process should be prioritized across all affected Exchange Server versions, with particular attention to the CU updates that specifically address this vulnerability. Network segmentation and access controls should be implemented to limit exposure of Exchange servers to untrusted networks, while monitoring solutions should be configured to detect anomalous web request patterns that may indicate exploitation attempts. Additionally, organizations should conduct comprehensive security assessments of their Exchange environments to identify any potential exploitation indicators and implement proper input validation measures to prevent similar vulnerabilities from occurring in other components of their email infrastructure. The vulnerability's classification under CWE-79 and its potential for privilege escalation make it a critical concern for organizations following ATT&CK framework methodologies for threat detection and response.