A critical remote code execution vulnerability (CVE-2023-21704) has been discovered in the Microsoft ODBC Driver for SQL Server. Exploiting this vulnerability could allow an attacker to execute arbitrary code with SYSTEM privileges on the server running the ODBC Driver. The vulnerability resides in the way the driver handles certain SQL queries, which, if exploited, can cause a buffer overflow and ultimately, remote code execution. Microsoft has acknowledged the issue and released a patch to address this vulnerability. This post delves into the technical details of this vulnerability and provides links to the original references, exploit details, and code snippets.

Code Snippet

The following code snippet demonstrates a vulnerable SQL query that could be used to trigger the buffer overflow and ultimately execute arbitrary code on the server:

DECLARE @buf_overflow NVARCHAR(400);
SET @buf_overflow = REPLICATE(N'a', 400);

-- This SELECT statement triggers the buffer overflow in the ODBC Driver
SELECT CONCAT(@buf_overflow, N'<some malicious payload>');

Exploit Details

The exploit for CVE-2023-21704 involves crafting a malicious SQL query that causes the buffer overflow in the ODBC Driver. When the SQL Server processes the malicious query, it prompts the ODBC Driver to allocate memory for the result, but due to incorrect memory handling, it results in a buffer overflow. This overflow can be leveraged by an attacker to execute arbitrary code with SYSTEM privileges on the target system.

A successful exploit of CVE-2023-21704 can have severe consequences, as attackers could potentially gain complete control over the compromised system, gaining unauthorized access to critical data, and spreading malware or launching further attacks.

Original References

Microsoft Security Advisory: CVE-2023-21704

Microsoft Security Update Guide: Patch for ODBC Driver for SQL Server

Mitigations & Recommendations

1. Download and apply the security patch released by Microsoft for systems running the affected ODBC Driver for SQL Server.

2. Always use the latest version of software and drivers, as they often contain necessary security updates and bug fixes.

Restrict access to the SQL Server, allowing only trusted IP addresses and specific users.

5. Be cautious of untrusted SQL queries or stored procedures, especially from external sources. Ensure that all inputs are validated and sanitized.

Conclusion

CVE-2023-21704 is a significant vulnerability in the Microsoft ODBC Driver for SQL Server that could have severe consequences if exploited. Microsoft has released a security patch to address this vulnerability, and it is highly recommended to apply this patch to all affected systems as soon as possible. Additionally, it is essential to follow recommended security best practices to protect your systems from such vulnerabilities and to mitigate the potential risks associated with them.

Timeline

Published on: 02/14/2023 20:15:00 UTC
Last modified on: 02/23/2023 15:01:00 UTC