CVE-1999-0795 is a high-severity vulnerability affecting the NIS+ rpc.nisd server component on Sun Solaris systems. The rpc.nisd server is part of the Network Information Service Plus (NIS+), which is used for centralized management of system configuration data such as user and host information in Solaris environments. This vulnerability allows remote attackers to invoke certain Remote Procedure Calls (RPCs) without any authentication, enabling them to obtain sensitive system information, disable logging mechanisms, or modify internal caches. The lack of authentication means that an attacker can interact with the rpc.nisd server over the network without credentials, potentially leading to unauthorized disclosure of information, tampering with system state, and disruption of normal logging activities. The CVSS v2 score of 7.5 reflects the ease of exploitation (network vector, no authentication required), and the significant impact on confidentiality, integrity, and availability. Although this vulnerability was published in 1998 and no patches are available, it remains relevant for legacy Solaris systems still in operation. Exploitation could allow attackers to gather intelligence about the system, cover their tracks by disabling logs, and manipulate cache data, which may affect system behavior or security policies.

For European organizations running legacy Solaris systems with NIS+ enabled, this vulnerability poses a significant risk. Unauthorized access to system information can facilitate further attacks by revealing user accounts, hostnames, or configuration details. Disabling logging impairs incident detection and response capabilities, increasing the risk of prolonged undetected intrusions. Modifying caches could disrupt system operations or security controls, potentially leading to denial of service or privilege escalation scenarios. Organizations in sectors with high regulatory requirements for data protection and system integrity, such as finance, healthcare, and critical infrastructure, may face compliance issues if exploited. Additionally, the presence of this vulnerability could be leveraged by threat actors targeting outdated infrastructure, especially in environments where Solaris remains in use due to legacy application dependencies.

Given that no official patch is available, European organizations should consider the following specific mitigations: 1) Disable the NIS+ rpc.nisd service if it is not strictly required, as removing the vulnerable service eliminates the attack surface. 2) Restrict network access to the rpc.nisd server using firewall rules or network segmentation, allowing only trusted management hosts to communicate with it. 3) Monitor network traffic for unusual RPC calls targeting the rpc.nisd port to detect potential exploitation attempts. 4) Implement compensating controls such as enhanced logging at network perimeter devices and intrusion detection systems to identify suspicious activity. 5) Plan for migration away from Solaris NIS+ to more secure directory services or identity management solutions that support modern authentication and encryption. 6) Conduct regular security audits of legacy systems to identify and mitigate similar vulnerabilities.