CVE-1999-0223 in Solaris
Summary
by MITRE
Solaris syslogd crashes when receiving a message from a host that doesn't have an inverse DNS entry.
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Analysis
by VulDB Data Team • 04/18/2026
The vulnerability described in CVE-1999-0223 represents a critical denial of service flaw in Solaris syslogd implementations that persisted through multiple versions of the Sun Microsystems operating system. This issue specifically targets the syslog daemon's handling of network messages from hosts lacking proper reverse DNS resolution capabilities. The vulnerability manifests when the syslogd process attempts to process incoming log messages from remote systems that cannot be resolved through inverse DNS lookups, causing the daemon to terminate unexpectedly and resulting in complete loss of syslog functionality on the affected system. This behavior fundamentally undermines system monitoring and security auditing capabilities that depend on centralized logging services.
The technical root cause of this vulnerability lies in the syslogd implementation's failure to properly handle error conditions during hostname resolution operations. When the daemon receives a message from a remote host without a valid inverse DNS entry, the internal processing logic does not adequately account for this scenario, leading to a crash condition that terminates the syslog service. This represents a classic buffer over-read or improper error handling vulnerability where the system fails to gracefully manage exceptional network conditions. The flaw operates at the application layer within the network services stack, specifically affecting the syslog daemon's network message processing capabilities. According to CWE classification, this vulnerability aligns with CWE-248, which addresses an exception handling flaw where an unhandled exception leads to program termination, and potentially CWE-121, which covers stack-based buffer overflow conditions that can occur during improper string handling operations.
The operational impact of this vulnerability extends far beyond simple service disruption, as it compromises the fundamental logging infrastructure that security administrators rely upon for system monitoring, intrusion detection, and forensic analysis. When the syslogd daemon crashes, all network-based logging functionality ceases to operate, leaving system administrators blind to security events, system errors, and user activities that would normally be captured and stored in centralized log repositories. This creates a significant security gap where malicious activities can occur without detection, as the system's ability to log and report suspicious behavior is completely eliminated. The vulnerability also demonstrates how seemingly minor network configuration issues can cascade into major security incidents, as any host without proper inverse DNS resolution can potentially exploit this weakness to deny service to syslog collection services.
Mitigation strategies for this vulnerability should address both immediate remediation and long-term architectural improvements to system security. The most direct solution involves applying the appropriate security patches provided by Sun Microsystems, which typically include enhanced error handling routines that prevent the syslogd process from crashing when encountering hosts without inverse DNS entries. Organizations should also implement network configuration standards that ensure proper reverse DNS resolution capabilities are maintained across all systems participating in network logging operations. Additionally, system administrators should deploy redundant logging mechanisms and implement monitoring solutions that can detect syslog service failures and automatically restart the daemon when crashes occur. From an ATT&CK framework perspective, this vulnerability represents a denial of service technique that could be leveraged by adversaries to disrupt security monitoring capabilities, potentially enabling other attacks by eliminating audit trails that would otherwise detect malicious activity. The vulnerability also highlights the importance of network infrastructure hardening and proper DNS configuration as foundational security measures that prevent exploitation of application-level flaws.