CVE-2017-8642 in Edge
Summary
by MITRE
Microsoft Edge in Microsoft Windows 10 1703 allows an attacker to elevate privileges due to the way that Microsoft Edge validates JavaScript under specific conditions, aka "Microsoft Edge Elevation of Privilege Vulnerability". This CVE ID is unique from CVE-2017-8503.
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Analysis
by VulDB Data Team • 01/07/2021
The vulnerability identified as CVE-2017-8642 represents a critical privilege escalation flaw within Microsoft Edge browser that affects Windows 10 version 1703. This issue stems from insufficient validation mechanisms within the browser's JavaScript execution environment, creating a pathway for malicious actors to elevate their access rights from standard user level to system administrator privileges. The vulnerability specifically manifests when Microsoft Edge processes JavaScript code under certain conditional circumstances that bypass normal security boundaries.
The technical root cause of this vulnerability lies in the improper validation of JavaScript code execution contexts within Microsoft Edge's rendering engine. When specific JavaScript operations are performed within the browser, the validation mechanisms fail to properly enforce security boundaries between different execution contexts. This allows attackers to craft malicious JavaScript payloads that can exploit memory management flaws and bypass the standard security restrictions that normally prevent web content from accessing system-level resources. The vulnerability falls under the category of privilege escalation attacks, where an attacker can leverage a flaw in one component to gain elevated privileges within the operating system.
From an operational perspective, this vulnerability poses significant risks to enterprise environments where users may inadvertently visit malicious websites or receive compromised email attachments containing malicious JavaScript. The attack vector typically involves phishing campaigns or compromised websites that deliver malicious content designed to exploit this specific validation flaw. Once successfully exploited, the attacker gains system-level privileges which can be used to install persistent backdoors, modify system files, steal sensitive data, or establish command and control channels. The impact extends beyond individual user compromise to potentially enable lateral movement within network environments and full system takeover.
The vulnerability's classification aligns with CWE-20, which describes "Improper Input Validation" as the underlying weakness that enables this privilege escalation. This weakness allows attackers to manipulate input validation mechanisms, leading to unexpected behavior that can be exploited for privilege elevation. According to ATT&CK framework, this vulnerability maps to T1068, which covers "Exploitation for Privilege Escalation," and T1190, which covers "Exploitation of Remote Services." Organizations affected by this vulnerability should prioritize immediate patch deployment and implement additional security controls including browser hardening, network segmentation, and enhanced monitoring for suspicious JavaScript execution patterns.
Mitigation strategies should include immediate deployment of Microsoft's security patches released for Windows 10 version 1703, along with implementation of browser security measures such as disabling unnecessary JavaScript features, implementing content security policies, and utilizing sandboxing technologies. Network-level protections should include web filtering solutions that can detect and block malicious JavaScript content, while endpoint detection and response systems should be configured to monitor for abnormal privilege escalation behaviors. Security teams should also consider implementing user behavior analytics to identify potential exploitation attempts and establish incident response procedures specifically addressing privilege escalation vulnerabilities in browser environments.