CVE-1999-0384 is a medium-severity vulnerability affecting the Forms 2.0 ActiveX control included with Visual Basic for Applications (VBA) 5.0 and Microsoft Office 98. This ActiveX control can be exploited to read text from a user's clipboard when the user opens documents containing ActiveX content. The vulnerability arises because the control does not properly restrict access to the clipboard, allowing malicious documents to silently extract clipboard data without user consent. Since clipboard contents often include sensitive information such as passwords, personal data, or confidential text, unauthorized reading of this data poses a privacy and confidentiality risk. The attack vector requires a user to open a specially crafted document with embedded ActiveX controls, which then execute within the context of the Office application. No authentication is required, but user interaction is necessary to open the malicious document. The vulnerability has a CVSS v2 score of 4.6, reflecting its medium severity, with partial impact on confidentiality, integrity, and availability. Microsoft has released patches addressing this issue as part of their 1999 security bulletin MS99-001. There are no known exploits in the wild, and the vulnerability primarily affects legacy Office versions that are now obsolete and unsupported.

For European organizations, the impact of this vulnerability is generally low in modern environments due to the obsolescence of the affected software versions (Office 98 and VBA 5.0). However, organizations that still maintain legacy systems or archives using these older Office versions could be at risk. If exploited, attackers could silently harvest clipboard data, potentially exposing sensitive information such as credentials, confidential business data, or personally identifiable information (PII). This could lead to privacy breaches, data leakage, or facilitate further attacks such as credential theft or social engineering. The requirement for user interaction (opening a malicious document) limits the scope of exploitation but does not eliminate risk, especially in environments where users frequently exchange Office documents. The vulnerability does not allow remote code execution but can be a stepping stone in multi-stage attacks. Given the age of the vulnerability and the availability of patches, the primary impact today is on legacy systems that have not been updated or isolated.

European organizations should ensure that all legacy Microsoft Office installations, especially those running Office 98 or VBA 5.0, are updated with the security patches provided in MS99-001. Where updating is not feasible, organizations should isolate legacy systems from the network and restrict their use to minimize exposure. Implement strict email and document filtering to block or quarantine documents containing ActiveX controls or originating from untrusted sources. Educate users about the risks of opening unsolicited or suspicious Office documents, emphasizing the dangers of enabling ActiveX content. Consider disabling ActiveX controls in Office applications where possible or configuring Office security settings to prompt users before running ActiveX content. Regularly audit and inventory legacy software to identify and remediate unsupported versions. Finally, implement endpoint security solutions capable of detecting and blocking exploitation attempts involving clipboard access or suspicious ActiveX behavior.