LSTM-PPO: A Hybrid Deep Reinforcement Learning Framework with Asymmetric Reward Engineering for Real-Time Intrusion Detection in IIoT and SCADA Networks
Aug 2026· 2026 6th International Conference on Emerging Smart Technologies and Applications (eSmarTA)· pp. 1-7· 0 citations· 24 references
Abstract
The integration of SCADA systems with the Industrial Internet of Things (IIoT) has dramatically expanded the attack surface of critical infrastructure. Traditional intrusion detection systems (IDS) struggle with evolving threats, class imbalance (attack samples often <5%), and real-time constraints (<100 ms). Deep reinforcement learning (DRL) offers a sequential decision-making paradigm that adapts over time. This paper presents a hybrid LSTM-PPO framework that unifies temporal feature extraction (LSTM), synthetic minority oversampling (SMOTE), asymmetric reward engineering, and Proximal Policy Optimization (PPO). The LSTM captures multi-stage attack patterns, SMOTE addresses class imbalance exclusively on training data to prevent leakage, and the asymmetric reward heavily penalizes false negatives (-50) compared to false positives (-10), aligning with industrial safety priorities. PPO ensures stable and efficient policy learning. Extensive experiments on three benchmark datasets (WUSTL-IIoT-2021, NF-UNSW-NB15-v2, WUSTL-SCADA-2018) demonstrate near-perfect detection (up to 100% F1 on WUSTL-IIoT-2021, 99.99% accuracy on NF-UNSW-NB15-v2, 99.96% on WUSTL-SCADA-2018) with sub-microsecond inference latency (≈1 μs per sample on GPU batching, <25 μs for single sample). Cross-validation and ablation studies confirm robustness against overfitting and the contribution of each component. The framework meets real-time industrial requirements and outperforms state-of-the-art supervised and DRL-based IDS. Limitations include binary classification and adversarial robustness, which are left for future work.
Real-world IoT network security generates traffic at big-data scale with extreme class imbalance, temporal non-stationarity, and continuously evolving attack strategies that overwhelm static supervised classifiers. This paper presents a cognitive computing framework for network intrusion detection: a CNN–LSTM–DQN architecture with Prioritized Experience Replay (PER) evaluated on a 5,000,000-flow naturalistic sample of the TON_IoT Processed_Network dataset (4,000,000 training/1,000,000 temporally held-out test flows; 94.5% attack ratio) under a strict temporal split. The cognitive agent optimizes detection decisions using an Alerts per Million Flows (ARMF)-aware reward function that encodes both alert-fatigue cost and missed-attack penalty. We conduct a cross-attack-family generalization study: the methodology—architecture template, reward design, and hyperparameter calibration—is inherited from a framework previously validated on CSE-CIC-IDS2018, re-instantiated and retrained on the structurally different TON_IoT environment, and compared against the previously published benchmark. Initialization sensitivity is characterized across five independent random seeds using paired Wilcoxon signed-rank and t-tests. Across the five seeds, the proposed X2 model attains recall 0.833 ± 0.306 and F1 0.874 ± 0.241 (mean ± sample SD), versus the supervised X1 baseline at 0.858 ± 0.178 and 0.912 ± 0.116; the best-performing seed (42) achieves 97.52% accuracy, 98.02% attack recall, 99.46% precision, and 98.73% F1-score on 1,000,000 held-out XSS flows—an attack family entirely absent from training—with temporal stability variances of 4.63 × 10−7 (recall) and 1.38 × 10−7 (F1). The X2 advantage observed among the four stable seeds is not statistically demonstrated at n = 5 (statistical power ≈ 5.1%); the initialization-sensitivity finding itself, including one degenerate alert-suppression seed, is reported as a primary contribution. A formal, exactly additive ARMF decomposition distinguishes the detected-attack (structural) component (99.46%) from the model-induced false-positive component (0.54%), and we report a multi-seed, ARMF-aware cognitive IDS evaluation on naturalistic TON_IoT traffic under an unseen-attack-family test condition that, to the best of our knowledge, has not been reported in the surveyed RL-based NIDS literature.
Xin Su, Zhiquan Bai, K. Ramli et al.· Big Data and Cognitive Compu...· 1 citation
Distributed Denial-of-Service (DDoS) attacks remain among the most disruptive network threats, and detectors that generalize across attack families with low false-alarm rates are still an open problem. Propose an adaptive hybrid ensemble that unifies two gradient-boosting learners (Random Forest and Gradient Boosting) with three deep neural base learners (DNN, CNN-1D, and LSTM) under a weighted soft-voting rule whose weights are produced by a Reinforcement Learning (RL) policy. The RL agent treats the ensemble-weight simplex as its action space, observes a state vector built from validation-set diagnostic statistics, and is trained by REINFORCE-with-baseline to maximize a reward equal to validation F1 minus a small calibration penalty. The framework is formalized as a Markov decision process with one stochastic step per training episode, which decouples ensemble-weight learning from the (non-differentiable) outer F1 objective. On a 10,000-sample, 25-feature, five-class benchmark with 7% label noise, the proposed system reaches weighted F1 = 0.846, accuracy = 84.7%, MCC = 0.781, AUC = 0.952, and ECE = 0.039. Friedman and Nemenyi post-hoc tests over 50 CV folds confirm the RL-guided ensemble is significantly better than every individual base learner and uniform voting at α = 0.05 (Cohen's d = 0.96). An ablation isolates the RL policy and gradient boosting as the main drivers; a label-noise robustness study shows graceful degradation up to 20%; a head-to-head comparison against the Bonobo Optimizer (BO), GA, PSO, GWO, and WOA shows the best F1/wallclock trade-off.
Unknown authors· International Journal of Adv...· 0 citations
ShieldDRLNet is a hybrid deep reinforcement learning framework for proactive cloud-network intrusion detection that employs a convolutional neural network and a long short-term memory encoder to obtain a spatiotemporal traffic representation and uses a Double Deep Q-Network agent for adaptive sequential decision-making.
S. Venkatramulu, Anitha Patil, K. R. Pradeep et al.· Discover Computing· 0 citations
A Large Language Model-enhanced Autonomous Reinforcement Learning Penetration Testing framework that leverages the domain knowledge embedded in a Large Language Model to perform tactical planning, thereby pruning the original action space into a compact set of candidate actions.
A D2ANN-RL framework that integrates input/output sanitization, context isolation, sandboxing, and secure prompt engineering, supported by hybridization of Artificial Neural Network (ANN)–Reinforcement Learning (RL) detection model is introduced.
Victor Omoboye Oluwasegun, O. Falebita, Nabeela Temitayo Adebola et al.· Scientific Journal of Comput...· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.