CVE-2017-8517 in Internet Explorer
Summary
by MITRE
Microsoft browsers in Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 8.1 and Windows RT 8.1, Windows Server 2012 and R2, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016 allow an allow an attacker to execute arbitrary code in the context of the current user when the JavaScript engines fail to render when handling objects in memory in Microsoft browsers, aka "Scripting Engine Memory Corruption Vulnerability". This CVE ID is unique from CVE-2017-8522 and CVE-2017-8524.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/27/2020
This vulnerability represents a critical memory corruption flaw in Microsoft's JavaScript engines that affects multiple operating system versions and browser implementations. The issue stems from improper handling of objects in memory during JavaScript execution, specifically within the scripting engine components that process web content. When Microsoft browsers encounter certain malformed or crafted objects in memory, the JavaScript engine fails to properly manage memory allocation and deallocation, creating opportunities for attackers to exploit memory corruption patterns. The vulnerability impacts a broad range of Microsoft Windows operating systems including server versions 2008 and 2012, client versions 8.1 and 10, along with their respective service packs and update releases. This flaw operates at the core of browser security architecture where memory management failures can lead to arbitrary code execution, making it particularly dangerous for targeted attacks.
The technical nature of this vulnerability aligns with CWE-125, which describes out-of-bounds read conditions in memory management, and CWE-787, which covers out-of-bounds write operations. The memory corruption occurs during the rendering process of JavaScript objects, where the browser's scripting engine fails to validate object boundaries properly. Attackers can leverage this weakness by crafting malicious web content that, when processed by the vulnerable JavaScript engine, triggers memory corruption that can be exploited to execute arbitrary code with the privileges of the current user. The exploitability of this vulnerability is enhanced by the fact that it requires no user interaction beyond visiting a malicious website, making it particularly dangerous for drive-by attack scenarios. The attack surface extends across multiple Microsoft browser implementations including Internet Explorer and Edge, though the primary risk lies in Internet Explorer's legacy JavaScript engine which has been the focus of numerous similar vulnerabilities.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise when combined with other attack vectors. Successful exploitation allows attackers to bypass user privileges and execute malicious code in the context of the current user session, potentially leading to privilege escalation or lateral movement within a network. The vulnerability's presence in widely deployed operating systems creates substantial risk for enterprise environments where multiple systems may be simultaneously vulnerable. Organizations running affected versions of Windows are particularly at risk since the vulnerability affects not just individual user systems but entire server infrastructures that rely on Microsoft browsers for administration and user interaction. The vulnerability's classification as a remote code execution flaw means that attackers can exploit it from external networks without requiring local system access, making it a prime target for large-scale automated attacks. Security researchers have noted that this vulnerability follows patterns common to browser-based memory corruption issues, where improper memory management during object rendering creates exploitable conditions.
Mitigation strategies for this vulnerability require immediate patch deployment through Microsoft's regular security updates, specifically targeting the cumulative update releases that address the scripting engine memory corruption. Organizations should implement browser hardening measures including disabling unnecessary JavaScript features and implementing strict content security policies to limit the impact of potential exploitation attempts. Network segmentation and firewall rules can help limit lateral movement if exploitation occurs, while endpoint detection and response solutions should be configured to monitor for suspicious memory access patterns. The vulnerability's relationship to ATT&CK technique T1059.007, which covers scripting languages, demonstrates how attackers can leverage browser-based scripting engines to execute malicious payloads. System administrators should prioritize patch management processes to ensure all affected systems receive updates promptly, as this vulnerability has been widely exploited in the wild. Additionally, user education regarding safe browsing practices and the importance of keeping systems updated remains crucial in defending against this and similar memory corruption vulnerabilities.