Improper Input Validation in free5gc v4.0.1 Leads to DoS

Executive Summary

Improper input validation in the HandleUpdate function of free5gc v4.0.1 allows attackers to cause a Denial of Service via crafted input. The function reads entire request bodies without size limits, leading to memory exhaustion and process crashes.

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Detection Guidance

Monitor the UDM service logs for crashes or memory exhaustion errors after receiving large payloads. Check for HTTP 500 or 503 errors from the parameter provisioning endpoint. Use network traffic analysis tools like tcpdump or Wireshark to inspect incoming requests to the UDM HandleUpdate endpoint for unusually large payloads.

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Impact Analysis

An attacker could exploit this to crash the UDM service by sending oversized payloads, disrupting network operations. This may cause service outages, loss of connectivity, or degraded performance for users relying on the affected system.

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Compliance Impact

This vulnerability could indirectly impact compliance with GDPR or HIPAA by enabling DoS attacks that disrupt critical network functions. GDPR requires data protection measures, and HIPAA mandates availability of healthcare systems. A DoS condition may violate these requirements by degrading or denying access to essential services.

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Mitigation Strategies

Implement input size limits on the UDM HandleUpdate endpoint to reject oversized requests. Update to a patched version of free5GC if available. Use a web application firewall (WAF) to block large payloads before they reach the application. Monitor system memory usage to detect abnormal consumption patterns.

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