Splunk Enterprise is a leading data platform for searching, monitoring, and analyzing machine-generated data. However, in versions before 9..8, a security issue known as CVE-2024-23677 was discovered in the built-in diagnostic tool called RapidDiag. This vulnerability exposes sensitive server responses from external applications in plaintext within a log file, potentially leading to serious security incidents. In this article, we’ll explain the vulnerability, walk through what causes it, and provide details on how the issue can be identified and potentially exploited.

[Original References](#original-references)

## 1. Background: What Is RapidDiag?

RapidDiag is a Splunk Enterprise utility designed to collect troubleshooting data from deployments. Administrators can use it to automatically gather logs, configurations, and other diagnostic information to speed up issue resolution.

However, like every tool with deep access, it needs to be very careful about what data it logs—especially if it interacts with external systems.


## 2. Vulnerability Details

CVE-2024-23677 is a vulnerability present in Splunk Enterprise versions prior to 9..8. When using RapidDiag to gather diagnostic data, it may request information from various external applications or systems within your infrastructure. The responses from these external sources (which may include sensitive authentication data, error messages, or configuration dumps) are logged to Splunk’s RapidDiag logs, in plaintext.

Anyone with access to the log files can read sensitive information returned by external systems.

- These logs can persist for long periods, creating a treasure trove for attackers or even insider threats.


## 3. Code Snippet: How the Log Exposure Happens

While Splunk hasn’t publicly shared the exact source code, an example of how such a bug might appear in Python pseudocode is:

import requests
import logging

def gather_external_diag(url):
    response = requests.get(url)
    # Here is where the vulnerability happens:
    # Instead of sanitizing, the entire response is logged.
    logging.info(f"External app {url} responded: {response.text}")

If the response contains tokens, secrets, or internal configuration—they're now written to disk.

## 4. Exploit Walkthrough

Step 1: Get Access to Splunk RapidDiag Logs

An attacker either with file system access, or via a compromised Splunk account, can read RapidDiag logs typically located at:

$SPLUNK_HOME/var/log/splunk/rapid_diag.log

Open the log file and look for responses from external systems

cat $SPLUNK_HOME/var/log/splunk/rapid_diag.log

A leaked entry might look like

2024-04-15 10:23:12 INFO External app http://myinternaldb:808/metrics responded: {"username":"admin","password":"Secret123","token":"eyJhbGciOiJIUzI1..."}

Step 3: Extract Sensitive Data

Now, any attacker can pull credentials, tokens, or internal error messages for further exploitation, lateral movement, or privilege escalation.


## 5. How to Detect and Fix

Remove or securely archive any old diagnostic logs that may contain sensitive data.

Temporary mitigation: Limit access to log files, and use log sanitization scripts to remove obvious secrets until you can upgrade.


## 6. Original References

- Splunk Security Advisory for CVE-2024-23677
- NIST NVD Entry for CVE-2024-23677
- Splunk Docs: RapidDiag Overview

Final Thoughts

CVE-2024-23677 is a log disclosure vulnerability that underlines the importance of both secure logging practices and regular software updates. Even trusted internal tools can inadvertently leak sensitive data if not handled carefully. Auditors and defenders should routinely review diagnostic logs for secrets, and all Splunk environments should patch immediately.

Stay safe, and don’t overlook your logs—they may be saying more than you think!

Timeline

Published on: 01/22/2024 21:15:10 UTC
Last modified on: 01/29/2024 17:52:50 UTC