Microsoft Internet Explorer Scripting Engine Memory Corruption Remote Code Execution Vulnerability (CVE-2019-1367)

1. Vulnerability Overview & Root Cause

This vulnerability (CVE-2019-1367) is a memory corruption vulnerability that exists in the way the scripting engine (JScript.dll) handles objects in memory within Internet Explorer. Due to a flaw in the garbage collection mechanism, the engine fails to properly track active objects under specific conditions, leading to Use-After-Free (UAF) or out-of-bounds write conditions (CWE-787).

2. Exploitation Mechanics & Attack Scenario

To exploit this vulnerability, an attacker hosts a specially crafted website designed to trigger the memory corruption and lures users to view the site via Internet Explorer. Alternatively, attackers can embed an ActiveX control or a web view control inside Microsoft Office documents or emails to force the rendering of the malicious HTML/JS payload. Once the scripting engine parses the malicious script, it corrupts the memory layout, allowing the attacker to hijack the execution flow and run arbitrary shellcode.

3. Infrastructure & Business Impact

This vulnerability is listed in the CISA KEV (Known Exploited Vulnerabilities) catalog, confirming active exploitation in the wild. Successful exploitation allows attackers to execute arbitrary code with the privileges of the active user. If the user has administrative rights, the attacker can compromise the entire system, install malicious programs, exfiltrate sensitive data, and perform lateral movement across the enterprise network.