CVE-2024-20690 is a cryptographic vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting the Nearby Sharing feature. The vulnerability is classified under CWE-310, which relates to the use of insufficiently protected cryptographic mechanisms. Nearby Sharing is a Windows feature that allows users to share files, links, and other content wirelessly with nearby devices using Bluetooth and Wi-Fi. This vulnerability enables an attacker to perform spoofing attacks by exploiting weaknesses in the cryptographic protections that verify the authenticity of shared data or devices. The CVSS 3.1 base score is 6.5, indicating a medium severity level. The attack vector is network-based (AV:N), requiring no privileges (PR:N) but does require user interaction (UI:R), such as accepting a sharing prompt. The vulnerability impacts the integrity of the data shared (I:H) but does not affect confidentiality or availability. The scope is unchanged (S:U), meaning the vulnerability affects only the vulnerable component. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability could allow an attacker within wireless range to impersonate a trusted device or manipulate shared content, potentially leading to the delivery of malicious files or misinformation. The cryptographic flaw undermines the trust model of Nearby Sharing, making it possible to bypass intended security checks.

For European organizations, this vulnerability poses a moderate risk, especially in environments where Windows 10 Version 1809 is still in use and Nearby Sharing is enabled. The integrity compromise could lead to the distribution of malicious payloads or tampered data within corporate networks or between employees, potentially facilitating lateral movement or social engineering attacks. Although confidentiality is not directly impacted, the manipulation of shared content could disrupt business operations or lead to misinformation. Organizations with mobile or remote workforces using Nearby Sharing in office or public environments are particularly at risk due to the network-based attack vector. Given that Windows 10 Version 1809 is an older release, many enterprises may have upgraded, but legacy systems in critical infrastructure or industrial environments might still be vulnerable. The lack of known exploits reduces immediate risk, but the presence of a public CVE and medium severity score suggests that attackers could develop exploits, especially targeting sectors with high-value data or critical operations.

European organizations should first identify and inventory all systems running Windows 10 Version 1809 with Nearby Sharing enabled. As no official patch links are currently available, organizations should consider disabling Nearby Sharing on vulnerable systems as a temporary mitigation to prevent exploitation. This can be done via Group Policy or registry settings to restrict or disable the feature. Network segmentation and wireless access controls should be enforced to limit the exposure of devices to untrusted networks or users. Monitoring for unusual Nearby Sharing activity or unexpected file transfers can help detect potential exploitation attempts. Organizations should also prioritize upgrading affected systems to newer Windows versions where this vulnerability is addressed. Additionally, user awareness training should emphasize caution when accepting Nearby Sharing requests, especially from unknown or unexpected sources. Implementing endpoint detection and response (EDR) solutions that can flag suspicious file sharing or device spoofing behavior will further reduce risk.