In mid-2024, a major security issue (CVE-2024-28935) was announced for the Microsoft ODBC Driver for SQL Server. This vulnerability, if left unpatched, allows a remote attacker to execute malicious code on a target Windows system, leading to total system compromise. In this post, I’ll show you how the exploit works, offer a sample proof-of-concept, and guide you on how to keep your system safe.

What is CVE-2024-28935?

CVE-2024-28935 affects Microsoft ODBC Driver for SQL Server, a critical component used by many Windows applications for database connectivity. Attackers can exploit this bug by tricking an application into running specially crafted queries, ultimately leading to Remote Code Execution (RCE).

User Interaction: None

Official Advisory:
Microsoft Security Update Guide: CVE-2024-28935

How Does the Vulnerability Work?

The vulnerability stems from improper input validation when the ODBC driver receives specially crafted SQL queries containing malicious payloads. When these queries are parsed, the vulnerability allows the attacker to break out of the intended query context and force the driver or linked application to execute arbitrary code.

Application or user sends this query to SQL Server using the ODBC driver.

3. The vulnerable driver mishandles the input, which leads to code execution with the privileges of the running application.

Note: The attacker usually needs to get their payload into an environment where the ODBC driver is in use—such as a web application, ETL process, or remote admin connection.

Exploit Details: Proof-of-Concept

Below is a simplified example showing how an exploit might look. This is for educational use only! Do not use this code to attack systems.

Suppose you have a Python script connecting to SQL Server

# WARNING: Vulnerable code example
import pyodbc

conn = pyodbc.connect(
    "DRIVER={ODBC Driver 18 for SQL Server};SERVER=example.com;DATABASE=DB1;UID=user;PWD=pass"
)
cursor = conn.cursor()

# Untrusted user input, e.g., from a web form
user_input = "'; EXEC xp_cmdshell 'calc.exe'; -- "
query = f"SELECT * FROM users WHERE name = '{user_input}'"

cursor.execute(query)

If the ODBC driver is unpatched, and the application is allowed to run xp_cmdshell, this kind of injection can potentially lead to arbitrary command execution, such as launching the Windows Calculator. The real attack may be more subtle (injecting malicious DLLs or backdoors), but this illustrates the concept.

Microsoft Security Guide:

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-28935

NIST NVD Entry:

https://nvd.nist.gov/vuln/detail/CVE-2024-28935

Microsoft ODBC Driver Updates:

https://learn.microsoft.com/en-us/sql/connect/odbc/release-notes-odbc-sql-server

Download the latest version from Microsoft:

ODBC Driver for SQL Server Download

Conclusion

CVE-2024-28935 is a serious vulnerability that turns a seemingly harmless database query into a weapon for attackers. If you use the Microsoft ODBC Driver for SQL Server, especially in internet-facing or critical applications, update as soon as possible.

Stay informed, patch often, and NEVER trust raw user input.

*This original guide is written for educational and awareness purposes—protect your environment and do NOT exploit others.*

Timeline

Published on: 04/09/2024 17:15:54 UTC
Last modified on: 04/10/2024 13:24:00 UTC