CVE-2020-25927 in NicheStack TCPIP
Summary
by MITRE • 08/19/2021
The DNS feature in InterNiche NicheStack TCP/IP 4.0.1 is affected by: Out-of-bounds Read. The impact is: a denial of service (remote). The component is: DNS response processing in function: dns_upcall(). The attack vector is: a specific DNS response packet. The code does not check whether the number of queries/responses specified in the DNS packet header corresponds to the query/response data available in the DNS packet.
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Analysis
by VulDB Data Team • 08/21/2021
The vulnerability identified as CVE-2020-25927 affects InterNiche NicheStack TCP/IP version 4.0.1, specifically within the DNS feature implementation. This represents a critical security flaw that manifests as an out-of-bounds read condition during DNS response processing. The vulnerability occurs within the dns_upcall() function which handles DNS responses, making it a fundamental component in the network stack's DNS resolution capabilities. The flaw stems from insufficient validation of DNS packet structure integrity, where the system fails to verify that the query/response count specified in the DNS packet header accurately reflects the actual data present in the packet body.
The technical nature of this vulnerability aligns with CWE-129, which describes improper validation of array index bounds, and specifically manifests as a memory access violation during packet processing. When a malicious DNS response packet is received, the system attempts to read beyond allocated memory boundaries due to the unchecked header values. This occurs because the implementation does not perform proper bounds checking between the header-specified count of queries or responses and the actual data available within the packet payload. The attack vector requires only a specially crafted DNS response packet to trigger the condition, making it particularly dangerous as it can be exploited remotely without requiring authentication or privileged access.
The operational impact of CVE-2020-25927 results in a remote denial of service condition that can disrupt network operations and potentially cause system instability. When the out-of-bounds read occurs during DNS response processing, the affected system may crash, restart, or become unresponsive to further network requests. This vulnerability affects the core functionality of the TCP/IP stack, potentially compromising the availability of network services that depend on proper DNS resolution. The remote exploitation capability means that attackers can target systems without physical access or local network presence, making it a significant concern for network infrastructure and server environments. The denial of service impact extends beyond simple service interruption to potentially affect business continuity and network availability.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and bounds checking within the DNS response processing code. The recommended approach involves modifying the dns_upcall() function to validate that the number of queries or responses specified in the DNS packet header matches the actual data available in the packet payload before attempting any memory access operations. This aligns with ATT&CK technique T1210, which involves exploitation of remote services through input validation flaws. System administrators should prioritize updating to patched versions of InterNiche NicheStack TCP/IP where available, as the vendor has likely addressed this specific out-of-bounds read condition. Network monitoring should be enhanced to detect anomalous DNS response patterns that might indicate exploitation attempts, and defensive measures such as DNS response filtering and packet validation should be implemented to reduce the attack surface. The vulnerability demonstrates the importance of proper memory management and input validation in embedded networking systems, particularly those handling network protocol processing functions where malformed data can lead to system instability.