CVE-2019-0761 in Internet Explorer
Summary
by MITRE
A security feature bypass vulnerability exists when Internet Explorer fails to validate the correct Security Zone of requests for specific URLs, aka 'Internet Explorer Security Feature Bypass Vulnerability'. This CVE ID is unique from CVE-2019-0768.
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Analysis
by VulDB Data Team • 05/16/2020
The vulnerability described in CVE-2019-0761 represents a critical security feature bypass in Microsoft Internet Explorer that undermines the browser's core security model. This flaw specifically affects how Internet Explorer handles security zone validation for certain URL requests, creating a pathway for malicious actors to circumvent intended protection mechanisms. The issue stems from the browser's failure to properly verify the security zone context of incoming requests, allowing unauthorized code execution or data access that should be restricted based on zone boundaries. Such a bypass compromises the fundamental principle of zone-based security that Internet Explorer employs to isolate different types of content and limit their capabilities based on trust levels.
The technical implementation of this vulnerability exploits the browser's security zone handling mechanism where requests for specific URLs are not properly validated against their expected security context. When Internet Explorer processes these requests, it fails to enforce the appropriate security restrictions that should be applied based on the URL's zone classification, which typically includes internet, local intranet, trusted sites, and restricted sites. This failure creates a condition where malicious content can be executed in a higher privilege context than intended, effectively allowing attackers to bypass the sandboxing and access controls that should protect users from potentially harmful web content. The vulnerability specifically impacts how the browser validates the security zone of requests, enabling attackers to manipulate the execution environment and potentially gain unauthorized access to system resources or user data.
From an operational perspective, this vulnerability poses significant risks to organizations relying on Internet Explorer for business operations, as it allows attackers to bypass security controls that are essential for protecting corporate networks and user information. The impact extends beyond individual user sessions to potentially compromise entire network infrastructures, particularly in environments where legacy applications depend on Internet Explorer or where users may inadvertently visit malicious websites. Attackers can leverage this vulnerability to execute arbitrary code, access sensitive information, or perform actions that should be restricted based on security zone policies. The attack surface is particularly concerning given Internet Explorer's widespread use in enterprise environments and the potential for lateral movement within networks once initial access is achieved. This vulnerability can be exploited through various vectors including malicious web pages, email attachments, or compromised websites that trick users into visiting harmful content.
Organizations should implement immediate mitigations including disabling Internet Explorer or migrating to more secure browsers such as Microsoft Edge, which offers better security features and ongoing support. Microsoft has released patches addressing this vulnerability, and administrators should ensure all systems are updated with the latest security fixes. Additional protective measures include implementing strict browser policies, disabling unnecessary features, and deploying web application firewalls to monitor and filter potentially malicious traffic. The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1059.001 for command and scripting interpreter, as attackers can leverage the bypassed security controls to execute malicious code within the browser environment. Security teams should also consider network segmentation, user access controls, and regular security assessments to minimize the impact of such vulnerabilities and prevent exploitation attempts.