CVE-2024-39457
📋 TL;DR
This vulnerability allows attackers to inject malicious scripts into PDF previews in Cybozu Garoon. When exploited, these scripts execute in the browsers of logged-in users, potentially stealing session cookies or performing unauthorized actions. Organizations using Garoon versions 6.0.0 to 6.0.1 are affected.
💻 Affected Systems
- Cybozu Garoon
📦 What is this software?
Garoon by Cybozu
⚠️ Risk & Real-World Impact
Worst Case
Attackers could steal administrator session cookies, gain full system access, and compromise sensitive organizational data.
Likely Case
Attackers steal user session cookies to impersonate legitimate users and access their data/privileges.
If Mitigated
With proper input validation and output encoding, script execution is prevented, limiting impact to data display issues.
🎯 Exploit Status
Exploitation requires user to view a malicious PDF, but XSS payloads are well-documented and easy to craft.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 6.0.2
Vendor Advisory: https://kb.cybozu.support/?product=garoon&v=&fv=6.0.2&t=%E8%84%86%E5%BC%B1%E6%80%A7&f=&r=&b=&s=&posts_per_page=20
Restart Required: Yes
Instructions:
1. Backup your Garoon installation. 2. Download Garoon 6.0.2 from Cybozu support. 3. Follow the official upgrade guide. 4. Restart the Garoon service. 5. Verify the version is updated.
🔧 Temporary Workarounds
Disable PDF preview functionality
allTemporarily disable PDF preview features in Garoon to prevent exploitation.
Implement Content Security Policy
allAdd CSP headers to restrict script execution from untrusted sources.
Add 'Content-Security-Policy: default-src 'self'; script-src 'self'' to web server configuration
🧯 If You Can't Patch
- Implement web application firewall rules to block XSS payloads in PDF uploads
- Restrict PDF uploads to trusted users only and implement file type validation
🔍 How to Verify
Check if Vulnerable:
Check Garoon version in administration panel. If version is 6.0.0 or 6.0.1, system is vulnerable.Check Version:
Check 'System Information' in Garoon administration interfaceVerify Fix Applied:
After patching, verify version shows 6.0.2 or higher in administration panel.📡 Detection & Monitoring
Log Indicators:
- Unusual PDF uploads with script-like content
- Multiple failed PDF preview attempts
Network Indicators:
- HTTP requests containing XSS payloads in PDF parameters
SIEM Query:
source="garoon_logs" AND (message="PDF preview" OR message="PDF upload") AND (message CONTAINS "script" OR message CONTAINS "javascript")