CVE-2024-20656 is a high-severity elevation of privilege vulnerability affecting Microsoft Visual Studio 2017 versions 15.0 through 15.9.0. The vulnerability is classified under CWE-59, which pertains to improper link resolution before file access, commonly known as 'link following.' This flaw arises when the software incorrectly handles symbolic links or shortcuts, allowing an attacker with limited privileges to manipulate file paths and gain unauthorized access to files or escalate their privileges within the system. Specifically, the vulnerability allows a user with low-level privileges (PR:L) to exploit the improper link resolution mechanism to gain higher privileges (elevation of privilege) without requiring user interaction (UI:N). The CVSS v3.1 base score of 7.8 reflects the significant impact on confidentiality, integrity, and availability (all rated high) and the relatively low complexity of exploitation (AC:L). The attack vector is local (AV:L), meaning the attacker must have some level of access to the affected system to exploit this vulnerability. Although no known exploits are currently reported in the wild, the vulnerability's characteristics make it a serious concern for environments where Visual Studio 2017 is used, especially in development or build environments where elevated privileges could lead to broader system compromise or code integrity violations. The lack of available patches at the time of publication increases the urgency for organizations to implement interim mitigations and monitor for updates from Microsoft.

For European organizations, the impact of CVE-2024-20656 can be substantial, particularly in sectors heavily reliant on software development and engineering, such as finance, automotive, telecommunications, and critical infrastructure. An attacker exploiting this vulnerability could escalate privileges on developer workstations or build servers, potentially leading to unauthorized code modifications, insertion of malicious code into software builds, or access to sensitive intellectual property. This could undermine software supply chain integrity and lead to downstream compromises in deployed applications. Furthermore, elevated privileges could allow attackers to disable security controls, access confidential data, or disrupt development operations, affecting business continuity. Given the local attack vector, insider threats or compromised user accounts pose a significant risk. The vulnerability's presence in Visual Studio 2017, which remains in use in many enterprises despite newer versions, means that organizations with legacy development environments are particularly at risk. The absence of known exploits in the wild currently provides a window for proactive defense, but the high severity score underscores the need for immediate attention.

European organizations should take the following specific mitigation steps: 1) Inventory and identify all instances of Visual Studio 2017 (versions 15.0 through 15.9.0) within their environment, prioritizing critical development and build systems. 2) Apply any available patches or updates from Microsoft as soon as they are released; monitor Microsoft's security advisories closely. 3) Until patches are available, restrict local user permissions on systems running Visual Studio to the minimum necessary, preventing unprivileged users from accessing or modifying Visual Studio installation directories or related files. 4) Implement strict access controls and monitoring on developer workstations and build servers to detect unusual file system activities, particularly involving symbolic links or shortcut manipulations. 5) Employ application whitelisting and integrity verification mechanisms to detect unauthorized changes to development tools or build outputs. 6) Educate developers and IT staff about the risks of privilege escalation vulnerabilities and encourage prompt reporting of suspicious behavior. 7) Consider upgrading to newer supported versions of Visual Studio that do not have this vulnerability, if feasible, to reduce exposure. 8) Use endpoint detection and response (EDR) tools to monitor for exploitation attempts and lateral movement within the network.