CVE-2017-8523 in Edge
Summary
by MITRE
Microsoft Edge in Microsoft Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allows an attacker to trick a user into loading a page with malicious content when Microsoft Edge fails to correctly apply Same Origin Policy for HTML elements present in other browser windows, aka "Microsoft Edge Security Feature Bypass Vulnerability". This CVE ID is unique from CVE-2017-8530 and CVE-2017-8555.
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Analysis
by VulDB Data Team • 12/28/2020
The vulnerability described in CVE-2017-8523 represents a critical security flaw in Microsoft Edge browser that affects multiple Windows 10 versions and Windows Server 2016. This issue stems from an improper implementation of the Same Origin Policy, which is a fundamental security mechanism designed to prevent unauthorized access to resources across different origins. The vulnerability specifically manifests when Edge fails to correctly enforce cross-origin restrictions for HTML elements that exist in separate browser windows, creating a security feature bypass scenario that can be exploited by malicious actors.
The technical flaw in this vulnerability resides in Edge's handling of cross-origin resource sharing and window communication mechanisms. When a user navigates to a malicious webpage, the browser's failure to properly validate the origin of HTML elements in other windows allows attackers to execute unauthorized operations across different security contexts. This bypass occurs because Edge incorrectly permits access to resources that should be restricted by the Same Origin Policy, which is categorized under CWE-345 Insufficient Verification of Data Authenticity. The vulnerability specifically impacts the browser's ability to maintain proper isolation between different browsing contexts, enabling attackers to potentially access sensitive data or execute malicious code in ways that should otherwise be prevented.
The operational impact of this vulnerability is significant as it provides attackers with a means to circumvent browser security controls that are fundamental to protecting users from cross-site scripting attacks and data leakage. An attacker can craft malicious web pages that exploit this weakness to access content from other windows or tabs, potentially leading to information disclosure, session hijacking, or execution of arbitrary code within the victim's browsing context. This vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter and T1566.001 for Phishing, as it enables attackers to deliver malicious payloads through deceptive web content. The security implications extend beyond simple data access, as this bypass can potentially allow for more sophisticated attacks that leverage the compromised browser window to target other applications or systems within the user's environment.
Mitigation strategies for CVE-2017-8523 should prioritize immediate patching of affected systems, as Microsoft released security updates to address this specific vulnerability in their regular security bulletins. Organizations should implement browser hardening measures including disabling unnecessary browser features, implementing strict content security policies, and deploying web application firewalls to monitor and filter malicious content. Additionally, user education regarding phishing awareness and safe browsing practices remains crucial, as this vulnerability typically requires user interaction with malicious web content to be exploited. The remediation approach should also include monitoring for suspicious browser behavior and implementing network-level controls to detect and block known malicious domains associated with exploitation attempts. Security teams should consider implementing automated vulnerability scanning to identify unpatched systems and establish incident response procedures specifically addressing browser-based security bypass scenarios.