CVE-2023-30442 - Denial of Service in IBM Db2 (Linux, UNIX, Windows, and Connect Server) via Malicious Wrapper Options
Date: June 2024
Author: Security Daily Writeup
Introduction
IBM Db2 is a popular database management software for enterprise businesses, well-known for its stability and performance across Linux, UNIX, and Windows platforms—including the Db2 Connect Server edition. However, like all complex software, it is not immune to critical vulnerabilities.
*CVE-2023-30442* is a recently disclosed security vulnerability impacting Db2 federated servers (versions 11.1 and 11.5). It allows remote attackers to crash the Db2 server, thus causing a Denial of Service (DoS) via specially crafted wrappers and certain options. IBM has assigned it X-Force ID: 253202.
This long-read post offers an exclusive, easy-to-understand look at CVE-2023-30442, how the attack works, code snippets, real-world implications, and where to find the trusted references.
The Core Issue
Federated servers in Db2 are designed to allow you to connect to data outside your main database—for example, connecting from Db2 to Oracle, Informix, or SQL Server. This is achieved using wrappers, which act sort of like plug-ins, handling the communication between Db2 and the external sources.
The vulnerability lies in the server’s handling of wrappers—specifically, in how certain options given to a wrapper are processed.
If an attacker can execute a CREATE WRAPPER command (they need some privileges for this, see the attack vector below), and crafts the command with unexpected or malformed options, the server can crash. This opens the door to denial of service attacks, as the attacker can make the database server unavailable.
Later versions with the appropriate fix applied
Note: Privilege to execute CREATE WRAPPER is required for the exploit, typically grouped under DBAs or users handling federated data sources.
Below is a simplified code snippet to demonstrate how a Db2 federated wrapper is built
-- Standard usage
CREATE WRAPPER drda
LIBRARY 'db2drda'
OPTIONS (foo 'bar');
If an attacker provides malicious or malformed options, it triggers the flaw that leads to a crash.
Example Exploit Payload (Pseudo-Code)
-- Malicious use: passing options known to misuse underlying memory or logic
CREATE WRAPPER drda_bad
LIBRARY 'db2drda'
OPTIONS (foo 'bar', CRASHME 'true', OVERFLOW '1');
*Note*: These option names are for demonstration. The real payload would depend on reverse engineering and would use special options that Db2 does not properly guard against. According to IBM, this *does not* lead to privilege escalation or code execution—just a crash.
Realistic Exploit Scenario
1. Attacker gains access as a user with rights to create wrappers in a federated-enabled Db2 instance.
Attacker runs a specially crafted CREATE WRAPPER command using malformed or unexpected options.
3. Server processes the command and crashes—database connections for everyone using that Db2 instance are lost.
Proof-of-Concept (PoC) Code
Because IBM has not disclosed the exact payloads, here’s a template PoC that a threat actor might use (assuming internal research produced the dangerous option combination):
-- Replace 'BAD_OPTION' with the specific problematic option
CREATE WRAPPER drda_crash
LIBRARY 'db2drda'
OPTIONS (BAD_OPTION 'crash');
If the server crashes, you're seeing this vulnerability in action.
Server Crash: Database goes offline. All business processes tied to this instance halt.
- Denial of Service: Service downtime can range from seconds to hours, depending on monitoring and recovery automation.
- No Privilege Escalation or Data Loss: IBM reports that while the server crashes, there is no evidence of attackers gaining unauthorized privileges or directly stealing/modifying data.
Update Your Db2 Software:
IBM has released fixes via cumulative and special builds. See the official advisory (link below) for patch numbers matching your Db2 version.
Limit Wrapper Privileges:
Restrict who can create wrappers (CREATE WRAPPER privilege), ideally only DBAs or authorized integrators.
Monitor Crash Logs:
Watch the logs for unexplained server restarts or crashes, especially following CREATE WRAPPER commands.
IBM Official Advisory:
Security Bulletin: IBM Db2 is vulnerable to a denial of service (CVE-2023-30442)
IBM X-Force Exchange (253202):
https://exchange.xforce.ibmcloud.com/vulnerabilities/253202
NVD Entry:
https://nvd.nist.gov/vuln/detail/CVE-2023-30442
IBM Db2 Federated Documentation:
https://www.ibm.com/docs/en/db2/11.5?topic=connectivity-federation-components
Conclusion
CVE-2023-30442 is a serious, yet easily remediable, vulnerability in the IBM Db2 federated stack. While it won’t let attackers steal data or run code, if unpatched, your database could become a persistent target for DoS attacks that disrupt mission-critical processes.
Patch now, and restrict WRAPPER privileges. Protect your IBM Db2 investment—and your business’s uptime.
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Timeline
Published on: 07/10/2023 16:15:00 UTC
Last modified on: 07/31/2023 19:15:00 UTC