In a healthcare environment, the healthcare interoperability platforms based on HL7 FHIR allow concurrent, asynchronous access to a set of shared patient resources, which are independent systems, i.e., EHR systems, pharmacy systems, lab systems, and devices. The FHIR specification lacks a protocol for concurrency control, and the research on detecting a race condition only targets the OS kernel. The research on FHIR security only targets authentication and injection attacks, considering concurrent access to patient resources to be sequential. The gap in the research in this area is addressed through the introduction of FHIR Resource Access Graph (FRAG), a formally defined graph G = (P,R,E, λ, τ, S), in which the nodes are the concurrent processes, the typed edges represent the resource access events, and the race conditions are represented as detectable structural properties. Three clinically relevant race condition classes are formally specified: Simultaneous Write Conflict (SWC), TOCTOU Authorization Violation (TAV), and Cascading Update Race (CUR). The FRAG model is implemented as a three-pass graph traversal detection algorithm and tested against a time window-based baseline on 1,500 synthetic FHIR R4 transaction logs. Under full concurrent access (C2), FRAG attains a 90.0% F1 score vs. 25.5% for the baseline, a 64.5 pp improvement.

翻译：在医疗环境中，基于HL7 FHIR的医疗互操作性平台允许对一组共享的患者资源（这些资源是独立系统，如EHR系统、药房系统、实验室系统和设备）进行并发、异步访问。FHIR规范缺乏并发控制协议，而针对竞争条件检测的研究仅针对操作系统内核。关于FHIR安全性的研究仅关注身份验证和注入攻击，将患者资源的并发访问视为顺序执行。本文通过引入FHIR资源访问图（FRAG）来填补该领域的研究空白。FRAG是一个形式化定义的图G = (P,R,E, λ, τ, S)，其中节点表示并发进程，带类型边表示资源访问事件，竞争条件被表示为可检测的结构属性。本文形式化定义了三种临床相关的竞争条件类别：同时写入冲突（SWC）、TOCTOU授权违规（TAV）和级联更新竞争（CUR）。FRAG模型被实现为一种三遍图遍历检测算法，并在1500条合成FHIR R4事务日志上，与基于时间窗口的基线方法进行了测试。在完全并发访问（C2）条件下，FRAG的F1得分达到90.0%，而基线方法仅为25.5%，性能提升了64.5个百分点。