CVE-2024-21352 - Breaking Down the Microsoft WDAC OLE DB Provider for SQL Server RCE Vulnerability

In February 2024, Microsoft patched a critical vulnerability identified as CVE-2024-21352, affecting the WDAC OLE DB Provider for SQL Server. This vulnerability allowed remote attackers to execute arbitrary code on target systems. In this deep-dive, we’ll unpack what this vulnerability is, how it works, and what you can do to protect your environment. We will also provide code snippets and demonstrations for educational purposes.

What is CVE-2024-21352?

CVE-2024-21352 affects the Microsoft WDAC OLE DB Provider for SQL Server (commonly referred to as MSOLEDBSQL). OLE DB is a Microsoft technology that allows access to different data sources uniformly. Applications using this driver to connect to SQL Server could become exposed if not patched.

Severity: Critical
CVSS Score: 8.8 (High)
Attack Vector: Remote
Impact: Remote Code Execution (RCE)

Official Sources

- Microsoft Security Update Guide
- NVD CVE Details

How Does CVE-2024-21352 Work?

The vulnerability arises from improper validation of objects in memory when processing malformed OLE DB requests. A remote attacker that successfully exploits this flaw can run arbitrary code in the context of the application using the OLE DB provider.

Scenario:
If you have a web application or service using MSOLEDBSQL to interface with SQL Server, an attacker could send a specially crafted query or payload to trigger the RCE. No user interaction is required—making unpatched systems especially risky.

Below, let’s see an example of code that would be vulnerable if not patched

// Vulnerable code sample (DO NOT USE IN PROD)
using System.Data.OleDb;

string connStr = "Provider=MSOLEDBSQL;Data Source=SERVER;Initial Catalog=DB;User Id=sa;Password=pass;";
using (var conn = new OleDbConnection(connStr))
{
    conn.Open();
    using (var cmd = conn.CreateCommand())
    {
        // User input not sanitized
        string userQuery = Request.QueryString["sql"];
        cmd.CommandText = userQuery;
        var reader = cmd.ExecuteReader(); // This is where the exploit can occur
    }
}

What happens here?
If the attacker sends a malicious query through userQuery, the vulnerable OLE DB provider interprets malformed requests and may give control of the execution flow to the attacker.

Exploit Example (Conceptual)

The actual exploit details are not released publicly by Microsoft for safety. But in general, a successful attack might look like:

Example Attack Vector (illustrative, not real-world exploit)

GET /vulnerableapp?sql=EXEC('malicious_code_here') HTTP/1.1

If your application directly passes sql commands from user input to the OLE DB provider without validation or sanitation, your server could be owned.

How to Mitigate

1. Patch immediately!
- Install the security update from MSRC: February 2024 Security Updates
- Update your OLE DB driver from the official download page.

2. Never concatenate direct user input into database queries. Always sanitize and parameterize inputs.

3. Restrict application permissions. Make sure applications running OLE DB have only the permissions they need.

References

- Microsoft Security Guidance for CVE-2024-21352
- National Vulnerability Database Entry
- MSOLEDBSQL Documentation

Conclusion

CVE-2024-21352 is a high-risk RCE vulnerability in Microsoft’s WDAC OLE DB Provider for SQL Server. Unaddressed, it can allow remote attackers to fully compromise your server or business-critical apps. Patch now, audit your applications, and always treat user input with caution.

Timeline

Published on: 02/13/2024 18:15:51 UTC
Last modified on: 02/13/2024 18:22:58 UTC