CVE-1999-0784 in Database Server
Summary
by MITRE
Denial of service in Oracle TNSLSNR SQL*Net Listener via a malformed string to the listener port, aka NERP.
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Analysis
by VulDB Data Team • 04/07/2017
The vulnerability identified as CVE-1999-0784 represents a critical denial of service weakness in Oracle's TNSLSNR SQL*Net Listener component, commonly referred to as the Network Error Reporting Protocol or NERP. This flaw resides within Oracle's database networking stack and specifically targets the listener service that manages client connections to Oracle database instances. The vulnerability manifests when the listener receives malformed string inputs through its network port, causing the service to crash or become unresponsive, thereby disrupting legitimate database access for authorized users.
The technical implementation of this vulnerability exploits weaknesses in the listener's input validation mechanisms within the Oracle Net Services framework. When malicious or malformed strings are sent to the listener port, typically port 1521 for Oracle databases, the system fails to properly handle these inputs and subsequently crashes or enters an unstable state. This occurs because the listener lacks adequate bounds checking and input sanitization routines to properly process unexpected string formats. The flaw operates at the network protocol level, making it particularly dangerous as it can be exploited remotely without requiring authentication credentials, allowing attackers to cause service disruption simply by sending crafted network packets to the vulnerable listener.
The operational impact of this vulnerability extends beyond simple service interruption, as it can severely compromise database availability and business continuity for organizations relying on Oracle database systems. When the listener service becomes unavailable, all database connections are severed, potentially affecting thousands of users and applications that depend on the database for their operations. This vulnerability particularly affects enterprise environments where Oracle databases are extensively used for critical business applications, financial systems, and data management platforms. The remote exploit nature means that attackers can target vulnerable systems from anywhere on the network, making it a significant threat to database security infrastructure and potentially enabling more sophisticated attacks if followed by other exploitation techniques.
Organizations should implement immediate mitigations including network segmentation to restrict access to listener ports, firewall rules to limit connections to trusted IP addresses, and regular patching of Oracle database software to address known vulnerabilities. The vulnerability aligns with CWE-129 Input Validation and CWE-20 Improper Input Validation, both of which are fundamental security weaknesses in software design that allow malformed inputs to cause system instability. From an attack framework perspective, this vulnerability maps to the ATT&CK technique T1499.004 for Network Denial of Service and T1566.001 for Phishing, as attackers may use this weakness as part of broader attack campaigns targeting database infrastructure. System administrators should also consider implementing intrusion detection systems to monitor for unusual traffic patterns on Oracle listener ports and establish robust monitoring procedures to detect potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar weaknesses in database networking components throughout the enterprise infrastructure.