CVE-2018-16599 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. Out of bounds memory access during parsing of NBNS packets in prvTreatNBNS can be used for information disclosure.
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Analysis
by VulDB Data Team • 04/18/2020
The vulnerability identified as CVE-2018-16599 represents a critical memory safety issue affecting multiple embedded networking components including AWS FreeRTOS versions through 1.3.1, FreeRTOS versions up to V10.0.1 with FreeRTOS+TCP, and the WITTENSTEIN WHIS Connect middleware TCP/IP component. This flaw manifests during the processing of NBNS (NetBIOS Name Service) packets within the prvTreatNBNS function, where improper bounds checking leads to out-of-bounds memory access patterns that can be exploited for information disclosure purposes. The vulnerability resides in the network protocol stack implementation of these embedded systems, specifically targeting the parsing logic for NetBIOS Name Service packets which are commonly used in local network discovery and name resolution operations.
The technical implementation of this vulnerability stems from inadequate input validation and memory boundary checking within the NBNS packet processing routine. When the prvTreatNBNS function receives and parses incoming NBNS packets, it fails to properly validate the packet structure and length before accessing memory locations that correspond to the packet data. This allows an attacker to craft malicious NBNS packets with malformed structures that cause the parser to read beyond allocated memory boundaries, potentially exposing sensitive data from adjacent memory regions including stack contents, heap data, or other critical system information. The flaw specifically aligns with CWE-129, which addresses improper validation of array indices, and CWE-787, which covers out-of-bounds write operations, though in this case the impact is information disclosure rather than code execution. The vulnerability demonstrates a classic buffer over-read condition that can be leveraged to extract information from the device's memory space.
From an operational impact perspective, this vulnerability poses significant risks to embedded IoT devices and network infrastructure components that rely on these networking stacks. The information disclosure capability can expose sensitive system data including authentication credentials, configuration parameters, network topology information, and potentially proprietary software details that could be valuable to adversaries. In environments where these devices are deployed, such as industrial control systems, smart grid infrastructure, or connected medical devices, the exposure of memory contents could lead to further exploitation opportunities including privilege escalation or system compromise. The vulnerability is particularly concerning because NBNS packets are commonly transmitted in local network environments and can be easily injected by attackers within the same network segment. According to ATT&CK framework category T1046, this vulnerability enables network service discovery and can be used for initial reconnaissance activities, while T1005 covers data from local system storage, which aligns with the information disclosure aspect of this flaw.
Mitigation strategies for CVE-2018-16599 should focus on implementing proper bounds checking and input validation within the NBNS packet parsing routines. System administrators should immediately update affected devices to patched versions of AWS FreeRTOS, FreeRTOS+TCP, or WITTENSTEIN WHIS Connect middleware where available. Network segmentation and firewall rules should be implemented to restrict NBNS packet transmission to trusted network segments only, as NBNS is primarily intended for local network use. Additionally, monitoring systems should be configured to detect unusual NBNS packet activity patterns that might indicate exploitation attempts. Organizations should also consider implementing intrusion detection systems that can identify malformed NBNS packets and alert on suspicious network behavior. The vulnerability highlights the importance of secure coding practices in embedded systems, particularly around memory management and input validation, as these components often operate in resource-constrained environments where security considerations are frequently secondary to functionality requirements.