CVE-1999-1097 is a medium-severity vulnerability affecting Microsoft NetMeeting version 2.1, an early video conferencing and collaboration tool. The vulnerability allows one client connected in a NetMeeting session to read the clipboard contents of another client without authorization. This occurs when a user presses CTRL-C in the chat box while the box is empty, triggering the clipboard data to be transmitted to the other client. The vulnerability exploits the clipboard sharing feature inherent in NetMeeting, which was designed to facilitate collaboration but lacks proper access controls in this version. The attack vector is network-based (AV:N), requires no authentication (Au:N), and has low attack complexity (AC:L). The impact includes partial confidentiality and integrity compromise (C:P/I:P/A:N), as an attacker can read sensitive clipboard data and potentially manipulate it. However, availability is not affected. No patches or fixes are available since this is a legacy product no longer supported by Microsoft. There are no known exploits in the wild documented for this vulnerability, likely due to the obsolescence of NetMeeting 2.1. Nonetheless, the vulnerability highlights risks in legacy collaboration tools that share clipboard data without proper isolation or user consent mechanisms.

For European organizations, the direct impact of this vulnerability today is minimal given that Microsoft NetMeeting 2.1 is an obsolete product, replaced by modern collaboration platforms. However, organizations that maintain legacy systems or use outdated conferencing tools for specific operational needs could be at risk of unauthorized data disclosure. Clipboard data often contains sensitive information such as passwords, confidential documents, or personally identifiable information (PII). An attacker exploiting this vulnerability could exfiltrate such data, leading to privacy breaches and potential compliance violations under regulations like GDPR. The vulnerability could also be leveraged as a foothold to gather intelligence within a network if legacy NetMeeting sessions are accessible internally or over VPNs. Although no known exploits exist, the lack of patches means that any residual use of NetMeeting 2.1 remains vulnerable. European organizations should be cautious about legacy collaboration tools and consider the risk of data leakage through clipboard sharing features.

Given that no patches are available for this vulnerability, the primary mitigation is to discontinue use of Microsoft NetMeeting 2.1 entirely. Organizations should migrate to modern, supported collaboration platforms that enforce strict access controls and user consent for clipboard sharing. For environments where legacy systems must remain operational, network segmentation should be implemented to isolate NetMeeting traffic and restrict access to trusted users only. Monitoring network traffic for unusual clipboard data transmissions could help detect exploitation attempts. User training should emphasize the risks of sharing sensitive data via clipboard in collaboration tools. Additionally, organizations should conduct an inventory of legacy software and remove or upgrade unsupported applications to reduce the attack surface. Employing endpoint protection solutions that can detect anomalous clipboard access or data exfiltration attempts may provide additional defense layers.