CVE-2018-16525 in Amazon Web Services FreeRTOS
Summary
by MITRE
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 allow remote attackers to execute arbitrary code or leak information because of a Buffer Overflow during parsing of DNS\LLMNR packets in prvParseDNSReply.
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Analysis
by VulDB Data Team • 04/18/2020
This vulnerability exists in multiple network stack implementations including AWS FreeRTOS versions through 1.3.1, FreeRTOS versions up to V10.0.1 with FreeRTOS+TCP, and WITTENSTEIN WHIS Connect middleware TCP/IP components. The flaw occurs during the parsing of DNS and LLMNR packets within the prvParseDNSReply function, creating a buffer overflow condition that can be exploited by remote attackers. The vulnerability represents a critical security risk as it allows for arbitrary code execution or information leakage through carefully crafted network packets that exploit the improper bounds checking in the DNS reply parsing logic.
The technical implementation of this vulnerability stems from insufficient input validation and buffer management within the network protocol parsing layer. When the system receives DNS or LLMNR replies, the prvParseDNSReply function fails to properly validate the length of incoming data before copying it into fixed-size buffers. This classic buffer overflow condition occurs because the implementation does not account for maliciously constructed packet payloads that exceed the allocated buffer space, leading to memory corruption that can be leveraged for code execution or data disclosure. The vulnerability specifically affects systems that process DNS responses or handle LLMNR (Link Local Multicast Name Resolution) traffic, which are commonly used in local network environments for hostname resolution.
The operational impact of this vulnerability is severe across multiple deployment scenarios including IoT devices, embedded systems, and network infrastructure components that rely on these FreeRTOS implementations. Attackers can remotely exploit this vulnerability to execute arbitrary code on affected systems, potentially gaining full control over the device or network component. Additionally, the information leakage aspect allows attackers to extract sensitive data from memory, including cryptographic keys, credentials, or system configuration details. The widespread adoption of these FreeRTOS versions across various industries including automotive, industrial control systems, and consumer electronics amplifies the potential impact, as many devices may be vulnerable to this remote code execution attack vector.
Mitigation strategies should focus on immediate patching of affected systems with updated FreeRTOS versions that include proper bounds checking and input validation. Organizations should implement network segmentation and access controls to limit exposure of vulnerable systems to untrusted networks. The implementation of network monitoring and intrusion detection systems can help identify exploitation attempts through unusual DNS or LLMNR traffic patterns. Security teams should also consider disabling unnecessary DNS and LLMNR services where possible, and implementing proper firewall rules to restrict incoming packets that could trigger the vulnerable parsing logic. This vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions, and represents a technique commonly mapped to ATT&CK tactic TA0002 (execution) and TA0003 (persistence) through remote code execution capabilities.