Credential compromise is one of the most widespread security threats, allowing adversaries to bypass traditional authentication measures and impersonate legitimate users. Traditional intrusion detection systems are often based on network-level or macro-behavioral indicators, which can be easily spoofed by an attacker, thus compromising the effectiveness of those mechanisms. This study presents an improved adaptive intrusion detection system to authenticate user behavior based on micro-digital behavioral profiling. It involves the use of timing of keystrokes, micro-mouse, navigation in the application, and interaction rhythm signatures. The proposed system uses a hybrid model consisting of Long Short-Term Memory (LSTM) sequence prediction and an Autoencoder reconstruction network to learn both structural and temporal variation of user behavior. Also, an adaptive learning module (implemented by a replay buffer and a drift-detection mechanism based on Kullback-Leibler divergence) to continually recalibrate the model when authentic user behavior varies. Experimental testing on a controlled set of 42 subjects in multiple sessions shows that the proposed model can achieve 94.8 0.91 F1-score and 0.05 false-positive rate, which outperforms the use of individual models; adaptive learning brings this number down by half in the case of drift.  The comparison analysis proves the superiority of the proposed system in the areas of anomaly detection, stability, and real-time performance, which demonstrates the viability of micro-behavior analytics as a high-resolution security layer that can be used as a persistent authentication and identity-based threat detector.