CVE-2017-8555 in Edge
Summary
by MITRE
Microsoft Edge in Microsoft Windows 10 1703 allows an attacker to trick a user into loading a page with malicious content when the Edge Content Security Policy (CSP) fails to properly validate certain specially crafted documents, aka "Microsoft Edge Security Feature Bypass Vulnerability". This CVE ID is unique from CVE-2017-8523 and CVE-2017-8530.
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Analysis
by VulDB Data Team • 12/28/2020
The vulnerability identified as CVE-2017-8555 represents a critical security flaw in Microsoft Edge browser that affects Windows 10 version 1703. This issue manifests as a security feature bypass that occurs when the browser's Content Security Policy (CSP) mechanism fails to properly validate specific maliciously crafted documents. The vulnerability exploits a fundamental weakness in Edge's security architecture where legitimate user interactions can be manipulated to load harmful content without proper validation. The flaw specifically targets the browser's ability to enforce security policies that should prevent execution of unauthorized scripts and content, creating a pathway for attackers to circumvent built-in protections. This bypass occurs during the page loading process when Edge encounters documents that have been specially constructed to exploit validation gaps in the CSP implementation.
The technical nature of this vulnerability stems from improper validation mechanisms within Edge's Content Security Policy enforcement system. When users navigate to web pages containing maliciously crafted documents, the browser's CSP fails to adequately inspect or reject these inputs before rendering them. This allows attackers to construct documents that appear legitimate to the browser's security checks but contain hidden malicious payloads. The vulnerability operates at the application level where Edge's security controls should prevent unauthorized content execution, but instead permits certain types of content that should be blocked. The flaw demonstrates a classic security bypass scenario where the intended protection mechanisms are circumvented through careful manipulation of input validation processes, enabling attackers to execute code or load malicious resources that would normally be restricted by CSP policies.
The operational impact of CVE-2017-8555 is significant as it provides attackers with a method to bypass browser security controls that are designed to protect users from various web-based attacks. This vulnerability could be exploited to deliver malicious scripts, download harmful payloads, or redirect users to phishing sites without triggering the normal security warnings that users expect to see. The attack vector typically involves social engineering where users are tricked into visiting compromised websites or opening malicious documents that have been crafted to exploit this specific validation flaw. Security researchers have noted that this vulnerability aligns with the CWE-119 weakness category, which encompasses issues related to improper input validation and memory handling. The flaw can be particularly dangerous in enterprise environments where users may encounter malicious content through legitimate business websites or email attachments that have been compromised.
Organizations and security professionals should implement immediate mitigations to address this vulnerability including applying Microsoft's security patches and updates as soon as they become available. Browser administrators should consider implementing additional security measures such as enhanced CSP policies that provide more granular control over content loading and execution. The vulnerability also highlights the importance of maintaining up-to-date security configurations and monitoring for suspicious user behavior that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and defense evasion where attackers can bypass security controls to maintain persistent access. Network security teams should monitor for unusual traffic patterns and implement web filtering solutions that can detect and block known malicious content patterns. The incident underscores the necessity of comprehensive security testing including validation of security policy enforcement mechanisms to prevent similar bypass vulnerabilities from being exploited in the future.