CVE-1999-1105 is a medium-severity vulnerability affecting Microsoft Windows 95 systems when the Remote Administration and File Sharing for NetWare Networks feature is enabled. Specifically, when an administrator logs in remotely under these conditions, the operating system automatically creates a hidden administrative share named C$. This share exposes the root of the system drive over the network, allowing remote attackers to map the network drive and read arbitrary files without requiring authentication. The vulnerability arises because the share is created with insufficient access controls, permitting unauthorized users to access sensitive files remotely. The CVSS score of 5.0 reflects a network attack vector with low complexity and no authentication required, impacting confidentiality but not integrity or availability. Although this vulnerability is dated and affects the obsolete Windows 95 platform, it demonstrates a classic example of insecure default administrative shares that can lead to unauthorized data disclosure. No patches are available, and no known exploits have been reported in the wild, likely due to the obsolescence of the affected system. However, the underlying principle of exposing administrative shares without proper access controls remains relevant in modern systems.

For European organizations, the direct impact of CVE-1999-1105 is minimal today because Windows 95 is no longer used in production environments. However, if legacy systems running Windows 95 are still present in isolated or specialized industrial environments, this vulnerability could allow remote attackers to access sensitive files, leading to confidentiality breaches. Unauthorized disclosure of sensitive data could result in compliance violations under regulations such as GDPR, especially if personal data is exposed. Additionally, attackers gaining access to system files could use this as a foothold for further network intrusion. The vulnerability does not affect system integrity or availability directly but compromises confidentiality, which can have reputational and legal consequences. European organizations should be aware that similar misconfigurations or legacy features in current systems could pose analogous risks.

Given that no patch is available for this vulnerability and the affected system is obsolete, the primary mitigation is to decommission or isolate Windows 95 systems from any network, especially from the internet or untrusted networks. Organizations should ensure that legacy systems are segmented within secure network zones with strict access controls. Disable Remote Administration and File Sharing for NetWare Networks features if these systems must remain operational. Network monitoring should be implemented to detect unauthorized attempts to access administrative shares. For modern systems, administrators should audit and restrict administrative shares, enforce strong authentication, and apply the principle of least privilege. Regular vulnerability assessments should include checks for exposed shares and misconfigurations to prevent similar issues.