CVE-2019-12101 in LibNyoci
Summary
by MITRE
coap_decode_option in coap.c in LibNyoci 0.07.00rc1 mishandles certain packets with "Uri-Path: (null)" and consequently allows remote attackers to cause a denial of service (segmentation fault).
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Analysis
by VulDB Data Team • 09/19/2023
The vulnerability identified as CVE-2019-12101 resides within the LibNyoci 0.07.00rc1 library, specifically in the coap_decode_option function located in the coap.c file. This flaw represents a critical security issue that manifests when processing certain CoAP (Constrained Application Protocol) packets containing malformed Uri-Path options with null values. The vulnerability stems from inadequate input validation and error handling within the option decoding mechanism, creating a path for malicious actors to exploit the library's processing logic.
The technical implementation of this vulnerability occurs when the coap_decode_option function encounters a CoAP packet where the Uri-Path option is present but contains a null value. The function fails to properly validate the option structure before attempting to process it, leading to a segmentation fault during memory access operations. This memory corruption results in a complete application crash and denial of service condition. The flaw specifically relates to improper handling of null pointer dereferences and uninitialized memory access patterns that are common in protocol parsing libraries. The vulnerability classifies under CWE-476 which identifies null pointer dereference issues in software implementations.
From an operational standpoint, this vulnerability presents a significant risk to any system utilizing LibNyoci for CoAP protocol handling, particularly in constrained environments such as IoT devices, embedded systems, or network infrastructure components. Remote attackers can exploit this weakness by crafting malicious CoAP packets with specifically formatted Uri-Path options containing null values, thereby triggering the segmentation fault and causing service disruption. The impact extends beyond simple denial of service as it can be leveraged in broader attack scenarios where persistent service disruption could compromise larger network operations or availability services. The vulnerability affects systems where CoAP services are exposed to untrusted networks or where packet filtering is inadequate.
Mitigation strategies for CVE-2019-12101 should prioritize immediate patching of the LibNyoci library to version 0.07.00rc2 or later, which contains the necessary fixes for proper null pointer validation. Network administrators should implement strict packet filtering rules to prevent malformed CoAP packets from reaching vulnerable systems, particularly focusing on Uri-Path option validation. Additionally, deploying intrusion detection systems capable of identifying and blocking suspicious CoAP traffic patterns can provide layered protection. The fix addresses the underlying issue by implementing proper null pointer checks and ensuring that option decoding functions validate input parameters before processing. Organizations should also consider implementing application-level sandboxing or containerization for CoAP services to limit the impact of potential exploitation attempts. This vulnerability aligns with ATT&CK technique T1499 which covers network denial of service attacks and demonstrates the importance of robust input validation in protocol implementations.