When it comes to cybersecurity, vulnerabilities in Microsoft’s database drivers get immediate attention. In February 2023, Microsoft patched CVE-2023-23375, a critical Remote Code Execution (RCE) vulnerability that affects both Microsoft ODBC and OLE DB drivers. This post aims to break down what CVE-2023-23375 is, how it could be exploited, and how you can protect your systems—even if you’re not a security expert.

What is CVE-2023-23375?

CVE-2023-23375 is a security flaw in Microsoft’s ODBC and OLE DB drivers for SQL Server that allows remote attackers to execute arbitrary code on an affected system. The vulnerability arises from improper handling of objects in memory during the processing of SQL Server responses.

Multiple supported versions of Windows

For full details, check Microsoft’s official page:  
🔗 Microsoft’s CVE-2023-23375 advisory

How Does the Exploit Work?

Attackers could exploit this bug by enticing a user or an application to connect to a malicious SQL Server. Upon connection, the malicious server would send specially crafted data back via the ODBC or OLE DB drivers, causing memory corruption and enabling code execution with the privileges of the application.

Visualizing the Exploit Flow

1. Victim runs client app that connects to SQL Server using Microsoft ODBC/OLE DB drivers.
2. Attacker controls SQL Server or intercepts the network traffic, sending bad data crafted to corrupt memory.
3. Malicious code executes on the victim’s machine in the context of the connecting app (potentially SYSTEM if a service).

Sample Vulnerable Code Scenario

Here’s a simplified code snippet in C# using OLE DB (for learning; do not try this on production systems):

using System;
using System.Data.OleDb;

class Program
{
    static void Main()
    {
        string connectionString = "Provider=SQLOLEDB;Data Source=attacker.com;Initial Catalog=TestDB;User Id=user;Password=pass;";
        using (OleDbConnection conn = new OleDbConnection(connectionString))
        {
            conn.Open(); // If attacker.com is malicious, this triggers the exploit
        }
    }
}

If an attacker controls the server (attacker.com), they can respond to the connect request with specially crafted data to trigger the RCE on the client’s system.

In-Depth: Triggering Remote Code Execution

Technical root cause: The bug lays in how the ODBC/OLE DB drivers handle responses from a SQL Server. By sending malformed tokens or structures, an attacker can manipulate memory allocation and overwrite return addresses or function pointers.

Proof-of-Concept (PoC) Skeleton:  
*Note: PoCs for this vulnerability are not publicly released as of writing. But researchers have demonstrated that custom malicious SQL Servers, using packet manipulation tools, can send payloads targeting the deserialization or improper parsing in the drivers.*

Wireshark or packet crafting tools like Scapy (Python) can be used to simulate a malicious SQL response, but actual exploitation requires deep knowledge of TDS (Tabular Data Streams) protocol and the inner workings of the drivers.

Mitigation

Microsoft has released security updates addressing this issue.  
🔗 MSRC Security Update Guide - CVE-2023-23375 Fixes

Patch: Update all ODBC & OLE DB drivers to the latest versions.

2. Restrict Outbound Connections: Don’t let applications connect to arbitrary/untrusted SQL Servers.
3. Monitor Network Activity: Use network monitoring to flag suspicious SQL traffic to unfamiliar external IPs.

Real-World Impact

If an application using these drivers connects (even unknowingly) to a rogue or compromised SQL Server—either through misconfiguration, phishing, or DNS poisoning—the attacker can potentially compromise the entire system. This is especially risky for high-privilege apps and backend services.

CVE-2023-23375 is a serious RCE bug affecting widely deployed Microsoft database drivers.

- Connecting to untrusted SQL Servers (intentionally or by accident) can lead to a full system compromise.

References

- Microsoft CVE-2023-23375 Official Advisory
- NVD Entry for CVE-2023-23375
- Microsoft Docs: ODBC Driver for SQL Server Security Updates
- Tabular Data Stream (TDS) Protocol Documentation

Timeline

Published on: 04/11/2023 21:15:00 UTC