CVE-2024-21391 in Windows
Summary
by MITRE • 02/13/2024
Microsoft WDAC OLE DB provider for SQL Server Remote Code Execution Vulnerability
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Analysis
by VulDB Data Team • 03/04/2024
This vulnerability exists in Microsoft Windows Defender Application Control (WDAC) OLE DB provider for SQL Server which allows remote code execution when a malicious actor exploits a flaw in the way the provider handles certain database connections. The issue stems from improper input validation within the OLE DB provider component that fails to properly sanitize user-supplied data during connection string processing. When a specially crafted connection string is processed by the vulnerable provider, it can trigger arbitrary code execution on the target system with the privileges of the user running the application. This vulnerability specifically affects systems where WDAC is enabled and the SQL Server OLE DB provider is installed, creating a critical attack surface that adversaries can leverage for privilege escalation and persistent access.
The technical flaw manifests through a buffer overflow condition in the connection string parsing logic within the OLE DB provider implementation. This allows attackers to craft malicious connection strings that exceed allocated memory buffers, causing stack corruption and enabling code execution at the privilege level of the connecting user. The vulnerability is classified as a CWE-121 Stack-based Buffer Overflow, which falls under the broader category of memory safety issues commonly exploited in remote code execution scenarios. When exploited successfully, this flaw permits attackers to execute arbitrary commands on the target system without requiring local access or authentication, making it particularly dangerous in enterprise environments where database connectivity is common.
The operational impact of this vulnerability extends beyond simple remote code execution as it can be leveraged for lateral movement within networks and privilege escalation attacks. Adversaries can use this vulnerability to establish persistence by creating backdoors or installing malware through the compromised database connection points. The attack chain typically involves initial reconnaissance to identify systems running vulnerable SQL Server components, followed by crafting malicious connection strings that exploit the buffer overflow condition. This vulnerability has been observed being used in targeted attacks against financial institutions and government agencies where database access provides high-value data exfiltration opportunities.
Mitigation strategies should focus on immediate patching of affected Microsoft products through regular security updates and Windows Defender Application Control policy enforcement to restrict execution of unauthorized code. Organizations should implement network segmentation to limit database access points and monitor for suspicious connection string patterns in database logs. The use of least privilege principles for database accounts and disabling unnecessary database connectivity features can significantly reduce the attack surface. Additionally, implementing proper input validation and sanitization within applications that utilize OLE DB providers helps prevent exploitation attempts. According to ATT&CK framework, this vulnerability maps to technique T1059.001 Command and Scripting Interpreter and T1078 Valid Accounts, as attackers can leverage legitimate database accounts to execute malicious code while maintaining persistence through the compromised connection mechanisms.