CVE-2002-1123 in SQL Server
Summary
by MITRE
Buffer overflow in the authentication function for Microsoft SQL Server 2000 and Microsoft Desktop Engine (MSDE) 2000 allows remote attackers to execute arbitrary code via a long request to TCP port 1433, aka the "Hello" overflow.
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Analysis
by VulDB Data Team • 06/23/2025
The vulnerability identified as CVE-2002-1123 represents a critical buffer overflow flaw in the authentication mechanism of Microsoft SQL Server 2000 and Microsoft Desktop Engine MSDE 2000. This weakness resides in the handling of incoming network requests on the standard SQL Server port 1433, specifically during the initial authentication handshake process. The flaw manifests when the server receives a malformed authentication request containing an excessively long string that exceeds the allocated buffer space, creating an exploitable condition that can be leveraged by remote attackers to gain unauthorized system access.
The technical implementation of this vulnerability stems from inadequate input validation within the SQL Server authentication function, which fails to properly bounds-check the length of incoming authentication data. When a maliciously crafted request is sent to port 1433, the server's authentication handler attempts to process the oversized data without sufficient buffer size verification. This condition creates a classic buffer overflow scenario where the excess data overwrites adjacent memory locations, potentially allowing an attacker to overwrite critical program execution pointers or inject malicious code. The vulnerability is particularly dangerous because it occurs during the initial connection phase, meaning that an attacker can exploit it without requiring any prior authentication credentials or network proximity to the target system.
From an operational perspective, this vulnerability presents a severe threat to database security infrastructure as it allows remote code execution with the privileges of the SQL Server service account. Attackers can leverage this flaw to execute arbitrary commands on the affected system, potentially leading to complete system compromise, data exfiltration, or the establishment of persistent backdoors. The attack vector requires only network connectivity to the target system on port 1433, making it particularly attractive to threat actors seeking to exploit unpatched database servers. The impact extends beyond immediate system compromise as successful exploitation can provide attackers with access to sensitive corporate data, facilitate lateral movement within network environments, and enable further attacks on connected systems.
The vulnerability aligns with CWE-121, which describes the classic stack-based buffer overflow condition, and demonstrates characteristics consistent with ATT&CK technique T1190, which involves exploiting vulnerabilities in remote services to gain initial access. Organizations running affected versions of SQL Server 2000 or MSDE 2000 are particularly vulnerable since these products are no longer supported by Microsoft, leaving them exposed to this and other known exploits. Security practitioners should implement network segmentation to restrict access to port 1433, deploy intrusion detection systems to monitor for exploitation attempts, and ensure that all systems are patched or migrated to supported database versions. The remediation strategy must include immediate patch deployment, network access controls, and comprehensive monitoring of authentication attempts to detect potential exploitation attempts. Additionally, organizations should consider implementing database activity monitoring solutions to detect anomalous authentication patterns that may indicate exploitation of this vulnerability.