CVE-2019-9750 in IoTivity
Summary
by MITRE
In IoTivity through 1.3.1, the CoAP server interface can be used for Distributed Denial of Service attacks using source IP address spoofing and UDP-based traffic amplification. The reflected traffic is 6 times bigger than spoofed requests. This occurs because the construction of a "4.01 Unauthorized" response is mishandled. NOTE: the vendor states "While this is an interesting attack, there is no plan for maintainer to fix, as we are migrating to IoTivity Lite."
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2019-9750 represents a significant security flaw within the IoTivity framework version 1.3.1 and earlier, specifically affecting the CoAP server interface implementation. This vulnerability enables malicious actors to exploit the protocol's response handling mechanism to launch distributed denial of service attacks through IP address spoofing techniques. The attack leverages the amplification factor inherent in the CoAP protocol's error response construction, where the reflected traffic volume reaches six times the size of the original spoofed requests, creating a substantial network impact that can overwhelm target systems and networks.
The technical root cause of this vulnerability lies in the improper construction of "4.01 Unauthorized" error responses within the CoAP server implementation. When the server receives a malformed or unauthorized request, it generates a response that includes excessive data payload information, particularly in the authentication challenge portion of the response. This flaw creates a scenario where an attacker can send spoofed requests with falsified source IP addresses to a vulnerable IoTivity server, causing the server to respond to the spoofed addresses with amplified traffic volumes. The specific implementation issue occurs in the response generation logic where the server fails to properly validate or limit the size of authentication challenge data included in the unauthorized response, creating an amplification factor that can be exploited at scale.
The operational impact of this vulnerability extends beyond simple network disruption, as it represents a serious vector for large-scale network attacks that can affect not only the targeted IoTivity implementations but also broader network infrastructure. The amplification factor of six times the original request size means that even modest spoofed traffic can generate massive response volumes, potentially overwhelming network bandwidth and causing legitimate services to become unavailable. This vulnerability particularly affects IoT environments where devices may be exposed to untrusted networks or where CoAP services are not properly secured with appropriate access controls and network segmentation measures.
Security practitioners should recognize this vulnerability as aligning with CWE-400, which addresses "Uncontrolled Resource Consumption," and as part of the broader ATT&CK framework's T1498 category for "Network Denial of Service." The vulnerability demonstrates how protocol-level implementation flaws can create fundamental security weaknesses that enable attackers to amplify their impact through simple spoofing techniques. Organizations using IoTivity versions 1.3.1 or earlier should consider immediate mitigations including network-level filtering of suspicious CoAP traffic, implementation of rate limiting mechanisms, and deployment of firewalls that can detect and block amplified response patterns. The vendor's stated migration to IoTivity Lite suggests that this issue will not receive further maintenance updates, making proactive mitigation strategies essential for existing deployments.
The broader implications of this vulnerability highlight the importance of proper error response handling in network protocols, particularly in IoT environments where resource constraints and network exposure create additional attack surface. This flaw demonstrates how seemingly minor implementation details in protocol handling can create significant security risks that enable large-scale attacks. Network administrators should implement monitoring for unusual traffic patterns and consider deploying intrusion detection systems that can identify the specific amplification signatures associated with this vulnerability, while also planning for the eventual migration to more secure protocol implementations that address these fundamental design issues.