CVE-2020-1058 in Internet Explorer
Summary
by MITRE
A remote code execution vulnerability exists in the way that the VBScript engine handles objects in memory, aka 'VBScript Remote Code Execution Vulnerability'. This CVE ID is unique from CVE-2020-1035, CVE-2020-1060, CVE-2020-1093.
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Analysis
by VulDB Data Team • 10/17/2020
This vulnerability represents a critical remote code execution flaw within Microsoft's VBScript engine implementation, specifically affecting how the engine manages object references in memory. The vulnerability stems from improper handling of object lifecycle management and memory operations within the scripting engine, creating opportunities for attackers to manipulate memory structures and execute arbitrary code. The flaw exists in the interaction between VBScript's object model and the underlying memory management system, where insufficient validation occurs during object deallocation and reference counting operations. This particular vulnerability affects systems running Windows operating systems with VBScript enabled, making it particularly dangerous in enterprise environments where scripting capabilities are commonly utilized. The issue was identified through analysis of how the VBScript engine processes object references during script execution, particularly when objects are created, modified, and eventually destroyed within memory.
The technical exploitation of this vulnerability occurs through carefully crafted VBScript code that triggers memory corruption conditions within the scripting engine. Attackers can leverage this flaw by constructing malicious scripts that manipulate object references in ways that cause the VBScript engine to execute unintended memory operations. The vulnerability typically manifests when the engine encounters specific patterns of object creation and destruction that result in memory pointers becoming invalid or corrupted, allowing attackers to redirect execution flow or inject malicious code. This exploitation technique aligns with common software security weaknesses documented in CWE-121, which addresses buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow vulnerabilities. The memory corruption occurs at the intersection of object-oriented programming concepts and low-level memory management, creating a pathway for privilege escalation and persistent access to compromised systems.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential system compromise and data exfiltration capabilities. When successfully exploited, the vulnerability allows attackers to execute code with the privileges of the user running the VBScript engine, which could range from standard user privileges to SYSTEM level access depending on the target system configuration. The attack surface includes web browsers that support VBScript execution, email clients processing malicious attachments, and any application that embeds VBScript functionality. Organizations using legacy applications or older Windows versions remain particularly vulnerable, as these systems often lack the security updates that would mitigate this specific memory management flaw. The vulnerability's impact is amplified by the fact that VBScript remains enabled by default in many Windows environments, and the exploitation techniques can be delivered through phishing emails, malicious websites, or compromised applications, making it a significant threat vector in enterprise security.
Mitigation strategies for this vulnerability require a multi-layered approach combining immediate patch management with operational security measures. Microsoft released security updates addressing this specific memory corruption issue, and organizations should prioritize deployment of the relevant security patches to prevent exploitation. Network segmentation and application whitelisting can help reduce the attack surface by limiting which systems can execute VBScript code, particularly in environments where scripting capabilities are not essential for business operations. Security monitoring should focus on identifying unusual VBScript execution patterns, suspicious memory access operations, and anomalous network connections that might indicate exploitation attempts. Implementing exploit prevention technologies such as exploit protection mechanisms, address space layout randomization, and control flow integrity checks can provide additional defense layers. Organizations should also consider disabling VBScript execution in web browsers and email clients where it is not required, following the principle of least privilege to minimize potential impact from successful exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date security patches and the risks associated with legacy scripting technologies that may contain unaddressed memory management issues.