CVE-2024-28940 - Deep Dive into the Microsoft OLE DB Driver for SQL Server Remote Code Execution Vulnerability

In early 2024, Microsoft patched a critical vulnerability, tracked as CVE-2024-28940, in the Microsoft OLE DB Driver for SQL Server. This vulnerability allows an attacker to execute arbitrary code remotely, potentially giving them full control of affected systems. In this article, we will break down what this vulnerability is, how it works, and how attackers might exploit it—with code examples and actionable references.

What is CVE-2024-28940?

CVE-2024-28940 is a Remote Code Execution (RCE) vulnerability found in the Microsoft OLE DB Driver for SQL Server (commonly used as the MSOLEDBSQL provider). OLE DB is a core database connectivity technology on Windows, and SQL Server is one of the world’s most popular databases. If an attacker leverages this bug successfully, they could run malicious code under the context of the user running the affected application.

Affected Versions:
OLE DB Driver for SQL Server up to version 18.7. (and possibly others, always check the latest advisories).

Attack Vector:
Typically, the vulnerability is triggered by maliciously formatted data handled by applications that use the driver to connect to Microsoft SQL Server.

Technical Details

Microsoft did not release public proof-of-concept code, but from patch analysis and component behavior, security researchers have pieced together the root cause. It lies in how the OLE DB driver parses incoming data. Specifically, a buffer overflow or similar memory corruption bug can occur when it processes certain crafted responses or queries.

Imagine you have an application code that executes a SQL command using the OLE DB driver, such as

using System.Data.OleDb;

string connStr = "Provider=MSOLEDBSQL;Server=myServer;Database=myDB;User Id=myUser;Password=myPass;";
using (var conn = new OleDbConnection(connStr))
{
    conn.Open();
    var cmd = new OleDbCommand("SELECT * FROM Users WHERE Name = '" + userInput + "'", conn);
    var reader = cmd.ExecuteReader();
    // ...
}

If the backend SQL Server can be controlled by an attacker (for example, a rogue SQL server or a MitM attack), it’s possible for it to send maliciously crafted responses that exploit the bug in the OLE DB driver when data is parsed by OleDbCommand or related classes.

Typical attack scenarios for CVE-2024-28940 include

- Rogue SQL Server scenario: The attacker tricks a client application into connecting to a compromised SQL Server, which sends back special binary payloads.
- Man-in-the-middle scenario: An attacker who can intercept traffic tampers with responses from a legitimate SQL Server.

Exploit code can (in theory) look like the following pseudo-code

# This is just a schematic, not a working exploit
# Attacker sets up an SQL Server emulator that accepts incoming connections
import socket

malicious_payload = b'\x41' * 1024  # Oversized response to trigger vulnerable code path

s = socket.socket()
s.bind(('...', 1433))
s.listen(1)
print("Waiting for victim to connect...")
conn, addr = s.accept()
print(f"Connection from {addr}")

# Handshake omitted for brevity

conn.sendall(malicious_payload)  # Sends malicious response

When a vulnerable application connects, the driver processes the malicious response, causing memory corruption and potentially running arbitrary code.

Detection

Look for crashes in applications using the affected OLE DB driver, unexpected exceptions, or connections to suspicious SQL Servers.

Mitigation

- Patch Immediately: Download and install the *latest* OLE DB Driver for SQL Server from Microsoft's official site:
Download Center - OLE DB Driver for SQL Server

Original References

- Microsoft Security Guidance for CVE-2024-28940
- Microsoft OLE DB Driver for SQL Server Docs

Exploit and Proof of Concept

At the time of writing, there is no public exploit available. However, security researchers advise that the complexity is moderate, and a sophisticated attacker could weaponize this vulnerability for targeted attacks.

Responsible disclosure and patching are critical. Bringing public, fully working exploit code is discouraged due to the impact on mission-critical business systems.

Final Thoughts

CVE-2024-28940 highlights the importance of keeping database drivers up to date and only communicating with trusted database servers. Applications using the Microsoft OLE DB Driver for SQL Server must be updated urgently.

If you manage or develop for Windows or SQL Server environments, please review your connection configurations and update your drivers—to keep your systems secure.

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Stay updated, stay protected.

Note: This article is for educational and defensive security purposes only. Do not use this information for unauthorized access or attacks.

Timeline

Published on: 04/09/2024 17:15:56 UTC
Last modified on: 04/10/2024 13:24:00 UTC