CVE-2017-8639 in Edge
Summary
by MITRE
Microsoft Edge in Windows 10 1607, 1703, and Windows Server 2016 allows an attacker to execute arbitrary code in the context of the current user due to the way that Microsoft browser JavaScript engines render content when handling objects in memory, aka "Scripting Engine Memory Corruption Vulnerability". This CVE ID is unique from CVE-2017-8634, CVE-2017-8635, CVE-2017-8636, CVE-2017-8638, CVE-2017-8640, CVE-2017-8641, CVE-2017-8645, CVE-2017-8646, CVE-2017-8647, CVE-2017-8655, CVE-2017-8656, CVE-2017-8657, CVE-2017-8670, CVE-2017-8671, CVE-2017-8672, and CVE-2017-8674.
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Analysis
by VulDB Data Team • 01/07/2021
This vulnerability represents a critical memory corruption flaw within Microsoft Edge's JavaScript engine that affects Windows 10 versions 1607 and 1703 along with Windows Server 2016. The issue stems from improper handling of objects in memory during JavaScript execution, creating a pathway for remote code execution attacks. The vulnerability specifically targets the scripting engine's memory management mechanisms, where the browser fails to properly validate or sanitize object references during rendering processes. This flaw enables attackers to craft malicious web content that can trigger memory corruption when Edge processes JavaScript code, potentially allowing arbitrary code execution with the privileges of the currently logged-in user.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds writes in heap-based buffers. The flaw operates through the browser's JavaScript engine's memory management system where objects are allocated, accessed, and deallocated during page rendering. When Edge encounters malformed or specially crafted JavaScript objects, the memory corruption occurs during the object lifecycle management, particularly during garbage collection or memory reallocation phases. This vulnerability is distinct from several related CVEs that target different aspects of the scripting engine, with CVE-2017-8639 specifically addressing memory corruption during object handling rather than other execution paths.
The operational impact of this vulnerability is severe as it allows attackers to execute arbitrary code remotely without requiring user interaction beyond visiting a malicious webpage. The attack surface is broad since Edge is the default browser on Windows systems, and the exploitation requires no special privileges beyond what the user already possesses. This creates a significant risk for enterprise environments where users may inadvertently visit compromised websites or receive malicious links through phishing campaigns. The vulnerability can be exploited through various attack vectors including drive-by downloads, compromised websites, or malicious advertisements, making it particularly dangerous for both individual users and organizations. The memory corruption allows attackers to potentially escalate privileges, install malware, steal sensitive information, or establish persistent access to affected systems.
Mitigation strategies should focus on immediate patch deployment through Microsoft's regular security updates, as this vulnerability was addressed in the July 2017 security bulletin. Organizations should implement network-based protections such as web application firewalls and content filtering solutions to block known malicious domains and content. Browser hardening measures including disabling unnecessary JavaScript features, implementing strict content security policies, and using sandboxing mechanisms can reduce the attack surface. Additionally, user education programs should emphasize the importance of avoiding suspicious websites and links. Security monitoring should include detection of unusual memory access patterns and browser process behavior that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of keeping browser software up to date and implementing defense-in-depth strategies to protect against sophisticated attacks targeting core browser components.