CVE-2002-0650 in SQL Server
Summary
by MITRE
The keep-alive mechanism for Microsoft SQL Server 2000 allows remote attackers to cause a denial of service (bandwidth consumption) via a "ping" style packet to the Resolution Service (UDP port 1434) with a spoofed IP address of another SQL Server system, which causes the two servers to exchange packets in an infinite loop.
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Analysis
by VulDB Data Team • 06/27/2021
The vulnerability described in CVE-2002-0650 represents a significant denial of service weakness in Microsoft SQL Server 2000 that exploits the server's keep-alive mechanism to consume network bandwidth resources. This flaw specifically targets the Resolution Service component that operates on UDP port 1434, a critical port used by SQL Server for network discovery and configuration information exchange. The vulnerability demonstrates how seemingly benign network protocols can be weaponized to create resource exhaustion conditions that effectively disable system functionality.
The technical implementation of this vulnerability relies on the manipulation of the SQL Server Resolution Service's response behavior when processing incoming packets. When a malicious actor sends a specially crafted ping-style packet to UDP port 1434 with a spoofed source IP address that matches another SQL Server system, the affected server responds by initiating communication with what it believes to be the legitimate target. This creates a scenario where two SQL Server instances begin exchanging packets in an infinite loop, with each system attempting to communicate with the other using the spoofed address. The mechanism operates through the protocol's design for service discovery and configuration reporting, where the Resolution Service responds to queries by providing information about available SQL Server instances on the network.
From an operational impact perspective, this vulnerability creates a substantial bandwidth consumption issue that can severely degrade network performance or completely disable the affected SQL Server instances. The infinite packet exchange loop rapidly consumes network resources, potentially leading to complete network saturation where legitimate traffic cannot traverse the network infrastructure. Organizations running SQL Server 2000 systems are particularly vulnerable because the service discovery mechanism was designed for convenience rather than security, making it susceptible to exploitation without requiring authentication or privileged access. This attack vector aligns with the attack technique described in the MITRE ATT&CK framework under network denial of service, specifically targeting service availability through resource exhaustion.
The vulnerability also demonstrates weaknesses in network protocol design and implementation that persist in many legacy systems. The keep-alive mechanism that was intended to ensure service availability becomes a point of exploitation when combined with the lack of proper source address validation in the Resolution Service. This type of vulnerability is classified under CWE-400 as an Uncontrolled Resource Consumption, where the system fails to properly validate input or limit resource usage. Organizations should implement network segmentation and access control measures to limit exposure to this vulnerability, including blocking UDP port 1434 from external networks and implementing firewall rules to restrict communication between SQL Server instances. The recommended mitigation strategies include disabling the Resolution Service when not required, applying appropriate network access controls, and upgrading to supported versions of SQL Server where these vulnerabilities have been addressed through improved protocol implementations and enhanced security features.