CVE-2017-8520 in Edge
Summary
by MITRE
Microsoft Edge in Windows 10 1703 allows an attacker to execute arbitrary code in the context of the current user when the Edge JavaScript scripting engine fails to handle objects in memory, aka "Scripting Engine Memory Corruption Vulnerability". This CVE ID is unique from CVE-2017-8499, CVE-2017-8521, CVE-2017-8548, and CVE-2017-8549.
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Analysis
by VulDB Data Team • 12/27/2020
The vulnerability identified as CVE-2017-8520 represents a critical memory corruption flaw within Microsoft Edge's JavaScript scripting engine that affects Windows 10 version 1703. This issue stems from improper handling of objects in memory during JavaScript execution, creating a pathway for arbitrary code execution with the privileges of the currently logged-in user. The vulnerability specifically targets the Edge browser's JavaScript engine, which is responsible for interpreting and executing JavaScript code within web pages, making it a prime target for attackers seeking to exploit web-based attack vectors. The flaw manifests when the scripting engine fails to properly manage memory objects, potentially leading to memory corruption that can be leveraged by malicious actors to execute unauthorized code.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions that can lead to memory corruption issues. The flaw occurs within the JavaScript scripting engine's memory management routines where objects are not properly validated or handled during execution, creating opportunities for attackers to manipulate memory contents through carefully crafted JavaScript code. This memory corruption vulnerability allows an attacker to overwrite memory locations with malicious payloads, potentially leading to complete system compromise when the browser executes the compromised JavaScript code. The vulnerability is particularly concerning because it operates within the context of the current user, meaning that successful exploitation would grant the attacker the same privileges and access rights as the user, including access to user data, files, and system resources.
The operational impact of CVE-2017-8520 extends beyond simple code execution, as it represents a significant escalation risk for attackers who can leverage this vulnerability in conjunction with other techniques. Attackers typically utilize this flaw by delivering malicious web content that triggers the vulnerable JavaScript engine when a user visits compromised websites or opens maliciously crafted documents. The vulnerability's exploitation requires minimal user interaction beyond normal browsing behavior, making it particularly dangerous in phishing campaigns or drive-by download scenarios. The attack surface is broad since Edge is the default browser on Windows 10 systems, and the vulnerability affects a large user base. Additionally, the fact that this vulnerability is distinct from other related CVEs in the same vulnerability family suggests it represents a unique memory management flaw that requires specific mitigation approaches rather than generic fixes.
Mitigation strategies for CVE-2017-8520 should focus on both immediate patching and operational security measures. Microsoft released security updates that addressed this specific memory corruption flaw, and system administrators should prioritize applying these patches to all affected Windows 10 systems. Organizations should also implement browser hardening techniques such as disabling unnecessary JavaScript features, implementing content security policies, and deploying web application firewalls to filter malicious content. The vulnerability's characteristics make it susceptible to exploit prevention through sandboxing mechanisms, though the memory corruption nature means that traditional sandboxing may not provide complete protection. Security monitoring should include detection of unusual JavaScript execution patterns and memory access anomalies that could indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving exploitation of known vulnerabilities and privilege escalation, making it a critical target for defensive measures that focus on patch management and user behavior monitoring. Organizations should also consider implementing multi-layered security approaches including network segmentation, user access controls, and regular security assessments to minimize the risk of successful exploitation.