CVE-1999-0247 in INN
Summary
by MITRE
buffer overflow in nnrpd program in inn up to version 1.6 allows remote users to execute arbitrary commands.
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Analysis
by VulDB Data Team • 10/26/2025
The vulnerability described in CVE-1999-0247 represents a critical buffer overflow flaw within the nnrpd program component of the InterNetNews (inn) software suite version 1.6 and earlier. This issue resides in the network news server daemon that handles incoming news articles and postings through the Network News Transfer Protocol. The buffer overflow occurs when the nnrpd program processes incoming data without proper bounds checking, allowing maliciously crafted input to overwrite adjacent memory locations. This fundamental flaw in input validation creates an exploitable condition that can be leveraged by remote attackers to gain unauthorized control over systems running vulnerable versions of the inn software.
The technical implementation of this vulnerability stems from improper handling of user-supplied data within the nnrpd daemon's processing routines. When remote users send specially crafted news articles or commands to the server, the program fails to validate the length of incoming data before copying it into fixed-size buffers. This classic buffer overflow condition allows attackers to overwrite stack variables, return addresses, and potentially executable code segments. The vulnerability specifically aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows data to be written beyond the allocated buffer boundaries. The attack vector operates over the network protocol port typically used for news server communications, making it accessible to any remote user with network connectivity to the affected system.
The operational impact of this vulnerability extends far beyond simple data corruption, as it provides remote code execution capabilities that can result in complete system compromise. An attacker who successfully exploits this buffer overflow can execute arbitrary commands with the privileges of the nnrpd process, which typically runs with elevated permissions to handle news server operations. This privilege escalation opportunity can lead to unauthorized access to sensitive data, system file manipulation, persistent backdoor installation, and potential lateral movement within network environments. The vulnerability affects systems that rely on news server functionality for communication and information distribution, making it particularly dangerous in environments where news servers are exposed to untrusted networks or internet-facing services. According to ATT&CK framework, this vulnerability maps to T1059.007 for command and scripting interpreter and T1068 for exploit for privilege escalation, representing the attack paths available to adversaries exploiting such memory corruption flaws.
Mitigation strategies for CVE-1999-0247 require immediate action to address the root cause through software updates and system hardening measures. The primary solution involves upgrading to inn version 1.7 or later, where the buffer overflow has been corrected through proper input validation and bounds checking mechanisms. System administrators should also implement network segmentation to limit access to news server ports, deploy intrusion detection systems to monitor for suspicious news protocol traffic, and consider disabling unnecessary news server functionality. Additional defensive measures include implementing proper access controls for news server operations, regularly monitoring system logs for unauthorized access attempts, and establishing network monitoring procedures to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of input validation and proper memory management in network services, reinforcing security best practices that align with NIST SP 800-144 guidelines for secure coding practices and system hardening procedures.