CVE-1999-0630 in Windows
Summary
by MITRE
The NT Alerter and Messenger services are running.
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability described in CVE-1999-0630 identifies the presence of NT Alerter and Messenger services running on Windows NT systems, which represents a significant security risk within enterprise network environments. These services were originally designed for system administration purposes but have been widely exploited by attackers due to their inherent security flaws and lack of proper authentication mechanisms. The NT Alerter service specifically broadcasts system alerts and messages across the network, while the Messenger service handles remote messaging capabilities that can be leveraged for various malicious activities.
The technical flaw lies in the fundamental design of these services which operate with minimal security controls and lack proper access validation. The Alerter service broadcasts messages without authentication requirements, making it susceptible to message injection attacks where unauthorized users can send malicious alerts to system administrators. The Messenger service, while designed to provide remote messaging capabilities, suffers from inadequate input validation and lacks proper privilege separation. Both services typically run with elevated privileges and listen on well-known ports, creating attack vectors that align with common penetration testing methodologies and exploit frameworks. This vulnerability is categorized under CWE-255 - Credentials Management and CWE-284 - Improper Access Control, as these services fail to properly enforce access controls and manage system credentials.
The operational impact of these running services extends beyond immediate security concerns to encompass broader network compromise risks. Attackers can exploit these services to conduct denial of service attacks, inject malicious alerts that may deceive system administrators, or even establish covert communication channels. The services can be leveraged for reconnaissance purposes, allowing threat actors to map network topology and identify vulnerable systems. These vulnerabilities are particularly dangerous in enterprise environments where administrators may inadvertently trust messages from these services without proper verification. The impact is further amplified by the fact that these services were designed for legacy environments and do not implement modern security standards such as encryption or secure authentication protocols. The presence of these services aligns with ATT&CK technique T1072 - Software Deployment Tools, as they can be used to facilitate lateral movement and privilege escalation within compromised networks.
Organizations should immediately disable these services through group policy settings or registry modifications to prevent exploitation. The recommended mitigations include implementing proper network segmentation to isolate these services, configuring firewall rules to block access to the relevant ports, and conducting comprehensive network scans to identify all systems running these vulnerable services. System administrators should also implement monitoring solutions to detect unauthorized access attempts or message injections targeting these services. The remediation process should include regular security assessments to ensure these services remain disabled and that no unauthorized re-enablement occurs. Additionally, organizations should establish policies for maintaining secure configurations and ensure that system updates and patches are properly applied to prevent the exploitation of known vulnerabilities in these legacy services.