CVE-2017-0203 in Edge
Summary
by MITRE
A vulnerability exists in Microsoft Edge when the Edge Content Security Policy (CSP) fails to properly validate certain specially crafted documents. An attacker could trick a user into loading a web page with malicious content, aka "Microsoft Edge Security Feature Bypass Vulnerability."
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Analysis
by VulDB Data Team • 11/28/2022
The vulnerability identified as CVE-2017-0203 represents a critical security feature bypass in Microsoft Edge browser that undermines the Content Security Policy implementation designed to protect users from cross-site scripting and other code injection attacks. This flaw specifically targets the browser's Content Security Policy enforcement mechanism, which serves as a critical defense layer against malicious web content that could otherwise exploit user sessions or compromise system integrity. The vulnerability stems from insufficient validation of specially crafted documents that can bypass the intended security controls, creating a pathway for attackers to circumvent the browser's built-in protection mechanisms.
The technical implementation flaw occurs within Edge's Content Security Policy validation logic where the browser fails to properly evaluate certain document structures and content types that should trigger security warnings or blocking mechanisms. This validation failure allows attackers to construct malicious web pages that appear legitimate to the browser's security checks while containing hidden malicious code or resources that can execute in the context of the user's browsing session. The vulnerability is particularly concerning because it operates at the policy enforcement level rather than a lower-level execution flaw, making it more difficult to detect and exploit through traditional security scanning approaches.
From an operational impact perspective, this vulnerability enables attackers to bypass Microsoft Edge's security features and execute malicious code in user contexts without proper authorization. The attack vector typically involves tricking users into visiting compromised websites or opening malicious documents that leverage the CSP bypass to load malicious scripts or resources. This security feature bypass can lead to session hijacking, data theft, credential compromise, and potential system compromise depending on the nature of the malicious content loaded. The vulnerability affects all versions of Microsoft Edge that implement Content Security Policy enforcement, making it particularly dangerous in enterprise environments where Edge browsers are widely deployed.
The vulnerability maps to CWE-284 Access Control Bypass and aligns with ATT&CK technique T1059 Command and Scripting Interpreter, as it enables attackers to execute malicious commands through compromised browser sessions. Organizations should implement immediate mitigations including deploying Microsoft security patches, configuring enhanced browser security policies, and implementing network-level protections such as web application firewalls to detect and block malicious content. Additional defensive measures include user education about suspicious website visits, implementation of strict CSP policies at the network level, and monitoring for unusual browser behavior that might indicate exploitation attempts. Regular security assessments of browser configurations and continuous monitoring for exploitation indicators remain essential components of a comprehensive defense strategy against this type of security feature bypass vulnerability.