CVE-2024-45300
📋 TL;DR
A race condition vulnerability in alf.io allows attackers to bypass promo code usage limits by exploiting timing gaps between validation and enforcement. This affects all alf.io deployments prior to version 2.0-M5, potentially allowing unauthorized discounts for event tickets.
💻 Affected Systems
- alf.io
📦 What is this software?
Alf by Alf
⚠️ Risk & Real-World Impact
Worst Case
Event organizers suffer significant revenue loss through unlimited promo code abuse, potentially bankrupting small events or conferences.
Likely Case
Limited financial loss from opportunistic attackers exploiting promo codes for discounted tickets, impacting event profitability.
If Mitigated
Minimal impact with proper rate limiting and monitoring, though some abuse may still occur before detection.
🎯 Exploit Status
Requires user account to apply promo codes, but exploitation is straightforward once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0-M5
Vendor Advisory: https://github.com/alfio-event/alf.io/security/advisories/GHSA-67jg-m6f3-473g
Restart Required: Yes
Instructions:
1. Backup your alf.io installation and database. 2. Update to version 2.0-M5 or later. 3. Restart the alf.io service. 4. Verify the fix by testing promo code limits.
🔧 Temporary Workarounds
Disable promo codes
allTemporarily disable all promo code functionality until patching is possible
Implement external rate limiting
allUse web application firewall or reverse proxy to limit promo code application requests per user
🧯 If You Can't Patch
- Implement strict monitoring of promo code usage patterns and alert on anomalies
- Manually review and audit all promo code applications for suspicious activity
🔍 How to Verify
Check if Vulnerable:
Check alf.io version via admin interface or by examining the application files for version markersCheck Version:
Check the application.properties or version file in the alf.io installation directoryVerify Fix Applied:
Test promo code limit enforcement by attempting to apply the same code multiple times rapidly📡 Detection & Monitoring
Log Indicators:
- Multiple successful promo code applications from same user in rapid succession
- Promo code usage exceeding configured limits
Network Indicators:
- Bursts of POST requests to promo code application endpoints
SIEM Query:
source="alf.io" AND (message="promo code applied" OR message="discount applied") | stats count by user_id, promo_code | where count > 1