CVE-2019-0809 in Visual Studio
Summary
by MITRE
A remote code execution vulnerability exists when the Visual Studio C++ Redistributable Installer improperly validates input before loading dynamic link library (DLL) files, aka 'Visual Studio Remote Code Execution Vulnerability'.
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Analysis
by VulDB Data Team • 05/16/2020
The vulnerability identified as CVE-2019-0809 represents a critical remote code execution flaw within the Visual Studio C++ Redistributable Installer component. This weakness arises from insufficient input validation mechanisms during the dynamic link library loading process, creating an exploitable condition that adversaries can leverage to execute arbitrary code on affected systems. The issue specifically impacts systems that have installed the Visual Studio C++ Redistributable packages, making it particularly concerning given the widespread deployment of these components across enterprise and consumer environments. The vulnerability stems from the installer's failure to properly sanitize and validate file paths and module names before attempting to load DLL files, which creates opportunities for malicious actors to inject and execute unauthorized code.
The technical exploitation of this vulnerability occurs through a classic DLL injection attack vector where an attacker crafts malicious input that bypasses the installer's validation checks. When the Visual Studio C++ Redistributable Installer processes certain input parameters, it fails to adequately verify the integrity and legitimacy of DLL files that are intended to be loaded. This improper validation allows an attacker to manipulate the loading sequence and potentially execute malicious code with the privileges of the installer process. The flaw falls under the category of improper input validation as classified by CWE-20, which specifically addresses weaknesses in the validation of input data that can lead to various security issues including code execution. The vulnerability demonstrates characteristics of a privilege escalation scenario where the installer's elevated privileges can be leveraged to compromise the entire system.
The operational impact of CVE-2019-0809 extends beyond simple remote code execution capabilities as it can be exploited in various attack scenarios including targeted attacks against specific systems or broader campaign-based exploitation. Organizations with outdated Visual Studio C++ Redistributable installations face significant risk of compromise, particularly in environments where the installer is executed with elevated privileges or where automated deployment mechanisms are in place. The vulnerability's remote execution capability means that attackers can exploit it without requiring physical access to the target systems, making it particularly dangerous in networked environments. According to ATT&CK framework methodology, this vulnerability maps to techniques involving execution through installer packages and DLL side-loading, both of which are categorized under the execution and privilege escalation domains. The risk assessment indicates that systems with the vulnerable redistributable components pose a high threat surface, especially when combined with other attack vectors that might be used in conjunction with this exploit.
Mitigation strategies for CVE-2019-0809 primarily focus on immediate patching and remediation efforts through Microsoft's security updates. Organizations should prioritize the deployment of the official Microsoft security patches that address the input validation issues within the Visual Studio C++ Redistributable Installer. Additionally, system administrators should implement network segmentation and access controls to limit the potential attack surface, particularly by restricting access to systems that may execute the vulnerable installer components. The implementation of application whitelisting policies can help prevent the execution of unauthorized DLL files, while regular security assessments should be conducted to identify and remediate any remaining vulnerable installations. Organizations should also consider monitoring for suspicious installation activities and implementing behavioral analysis tools that can detect anomalous DLL loading patterns. The vulnerability highlights the importance of maintaining current security patches and demonstrates how seemingly routine components like redistributable installers can present significant security risks when not properly validated. Security teams should also consider implementing the principle of least privilege for installer execution and regularly audit system configurations to ensure that vulnerable components are either removed or properly patched across all affected systems.