CVE-2018-16598 in Amazon Web Services FreeRTOS
Summary
by MITRE
An issue was discovered in Amazon Web Services (AWS) FreeRTOS through 1.3.1, FreeRTOS up to V10.0.1 (with FreeRTOS+TCP), and WITTENSTEIN WHIS Connect middleware TCP/IP component. In xProcessReceivedUDPPacket and prvParseDNSReply, any received DNS response is accepted, without confirming it matches a sent DNS request.
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Analysis
by VulDB Data Team • 04/18/2020
This vulnerability exists in AWS FreeRTOS versions through 1.3.1 and FreeRTOS up to V10.0.1 when used with FreeRTOS+TCP, as well as in WITTENSTEIN WHIS Connect middleware TCP/IP components. The flaw resides in the DNS processing functionality where the system fails to validate that incoming DNS responses correspond to previously sent DNS queries. This represents a fundamental security weakness in the network protocol handling mechanism that could be exploited by malicious actors to manipulate network communications.
The technical implementation of this vulnerability stems from the lack of correlation between outgoing DNS requests and incoming responses within the xProcessReceivedUDPPacket and prvParseDNSReply functions. When a device sends a DNS query to resolve a hostname, it expects a specific response that matches the original request parameters. However, the vulnerable code accepts any DNS response without verifying the transaction ID, query type, or other identifying characteristics that should confirm the response belongs to the specific query that was sent. This absence of validation creates a window where an attacker could inject malicious DNS responses that would be accepted as legitimate by the device.
The operational impact of this vulnerability is significant for IoT and embedded systems that rely on DNS resolution for network connectivity. Attackers could leverage this flaw to perform DNS cache poisoning attacks, redirecting traffic to malicious servers, or injecting false network information that could compromise device functionality. The vulnerability particularly affects devices that depend on DNS for service discovery, firmware updates, or communication with cloud services, potentially leading to complete system compromise or data exfiltration. This weakness aligns with CWE-20, which describes improper input validation, and represents a classic case of trust validation failure in network protocol implementations.
Mitigation strategies should focus on implementing proper DNS transaction ID matching and query validation before accepting DNS responses. Organizations should update to patched versions of FreeRTOS and FreeRTOS+TCP where the DNS response correlation has been properly implemented. Network segmentation and monitoring can help detect anomalous DNS behavior, while implementing DNS security extensions such as DNSSEC could provide additional protection layers. This vulnerability demonstrates the critical importance of proper input validation and transaction correlation in network protocols, aligning with ATT&CK technique T1071.004 for application layer protocol traffic filtering and T1566 for phishing attacks through DNS manipulation. Regular security assessments of embedded systems should include thorough examination of network protocol implementations to identify similar validation gaps that could be exploited by threat actors.