CVE-2017-8529 in Internet Explorer
Summary
by MITRE
Internet Explorer in Microsoft Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8.1 and Windows RT 8.1, and Windows Server 2012 and R2 allow an attacker to detect specific files on the user's computer when affected Microsoft scripting engines do not properly handle objects in memory, aka "Microsoft Browser Information Disclosure Vulnerability".
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Analysis
by VulDB Data Team • 12/28/2020
The vulnerability identified as CVE-2017-8529 represents a significant information disclosure flaw within Microsoft Internet Explorer's scripting engine implementation. This vulnerability specifically affects multiple versions of Windows operating systems including Windows 7 SP1, Windows Server 2008 R2 SP1, Windows 8.1, Windows RT 8.1, Windows Server 2012, and Windows Server 2012 R2. The flaw stems from improper handling of objects within memory by the affected scripting engines, creating an avenue for attackers to gain unauthorized knowledge about file existence on target systems. The vulnerability operates at the intersection of browser security and memory management, exploiting how Internet Explorer processes and manages objects during script execution.
The technical mechanism underlying this vulnerability involves the Microsoft scripting engines failing to properly validate or sanitize object references during memory operations. When Internet Explorer processes certain script content, particularly those involving Active Scripting technologies, the engines do not adequately protect against memory access patterns that could reveal file system information. This occurs through side-channel information leakage where attackers can infer the presence or absence of specific files based on timing variations or memory access behaviors. The vulnerability is classified under CWE-200 as "Information Exposure" and specifically relates to information leakage through improper object handling. This type of vulnerability falls within the ATT&CK framework under T1082 "System Information Discovery" as it enables adversaries to gather intelligence about the target system's file structure.
The operational impact of CVE-2017-8529 extends beyond simple information disclosure, as it provides attackers with valuable reconnaissance data that can inform subsequent attack phases. An attacker who successfully exploits this vulnerability can determine which files exist on a victim's system, potentially identifying sensitive documents, system binaries, or other targets of interest. This information can be particularly dangerous when combined with other reconnaissance techniques, as it allows attackers to tailor their approach based on the actual file structure present on the target. The vulnerability is particularly concerning in enterprise environments where attackers might use this information to identify system administration tools, sensitive corporate documents, or other valuable targets within the file system. The exploitability requires user interaction through malicious web content, making it a prime candidate for phishing campaigns or compromised websites that could deliver the malicious script content.
Mitigation strategies for this vulnerability require a multi-layered approach combining immediate patch management with operational security measures. Microsoft released security updates that address the underlying memory handling issues in the scripting engines, and organizations should prioritize applying these patches across all affected systems. Network-based protections such as web application firewalls and content filtering solutions can help detect and block malicious script content that attempts to exploit this vulnerability. Additionally, browser hardening measures including disabling unnecessary scripting capabilities, implementing strict content security policies, and using sandboxing technologies can reduce the attack surface. Security monitoring should focus on detecting unusual memory access patterns or timing variations that might indicate exploitation attempts. Organizations should also implement regular vulnerability assessments to identify and remediate similar issues in other browser components or scripting environments, as this vulnerability demonstrates the broader risk associated with improper object management in scripting engines. The remediation process should include comprehensive testing to ensure that patches do not introduce compatibility issues with existing applications while maintaining the security posture against this specific information disclosure threat.