CVE-2024-23304
📋 TL;DR
CVE-2024-23304 is a denial-of-service vulnerability in Cybozu KUNAI for Android that allows remote unauthenticated attackers to crash the application by performing specific operations. This affects all Android users running KUNAI versions 3.0.20 to 3.0.21. The vulnerability stems from improper handling of certain operations that can be triggered without authentication.
💻 Affected Systems
- Cybozu KUNAI for Android
📦 What is this software?
Kunai by Cybozu
Kunai by Cybozu
⚠️ Risk & Real-World Impact
Worst Case
Complete application crash rendering KUNAI unusable, potentially disrupting business operations that rely on the app for document management and collaboration.
Likely Case
Application becomes unresponsive or crashes, requiring restart and causing temporary disruption to user productivity.
If Mitigated
Minimal impact if patched version is deployed; unpatched systems remain vulnerable to DoS attacks.
🎯 Exploit Status
The vulnerability requires specific operations to trigger, but these can be performed without authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.22 or later
Vendor Advisory: https://cs.cybozu.co.jp/2024/010691.html
Restart Required: Yes
Instructions:
1. Open Google Play Store on Android device. 2. Search for 'Cybozu KUNAI'. 3. If update is available, tap 'Update'. 4. Restart the application after update completes.
🔧 Temporary Workarounds
Disable KUNAI network access
androidTemporarily block network access to KUNAI app to prevent remote exploitation
Uninstall vulnerable version
androidRemove the vulnerable app until patched version can be installed
🧯 If You Can't Patch
- Implement network segmentation to restrict access to KUNAI services
- Monitor for unusual traffic patterns or repeated connection attempts to KUNAI endpoints
🔍 How to Verify
Check if Vulnerable:
Check KUNAI app version in Android Settings > Apps > KUNAI > App infoCheck Version:
Not applicable - check via Android app settingsVerify Fix Applied:
Verify KUNAI version is 3.0.22 or higher after update📡 Detection & Monitoring
Log Indicators:
- Multiple connection attempts from single IP
- Application crash logs mentioning KUNAI
- Unusual operation patterns in KUNAI logs
Network Indicators:
- Spike in traffic to KUNAI endpoints
- Repeated connection attempts followed by disconnections
SIEM Query:
source="android_logs" AND app="KUNAI" AND (event="crash" OR event="unexpected_exit")