detection, which involves the discovery of hidden patterns and correlations in large-scale transaction data.
Supervised learning algorithms can be trained to differentiate between legitimate and fraudulent transactions
on the basis of labeled data. Machine learning-based systems enhance the accuracy of fraud detection by
modeling nonlinear relationships and adapting to new patterns of financial fraud. In the context of financial
fraud detection, compared with traditional statistical methods, ensemble learning algorithms and gradient
boosting algorithms have been found to perform better.
[12]
In the proposed research, a light gradient boosting machine (LightGBM)-based detection system is developed
for the detection of mule accounts in UPI transactions. LightGBM
[13]
is chosen for its efficiency, scalability, and
robustness on structured tabular data. The system uses the concept of gradient boosting to learn from mistakes
in classification and reduce them while addressing large datasets and class imbalance issues. The proposed
system combines preprocessing methods, feature extraction, and the synthetic minority over-sampling
technique (SMOTE)
[14]
to improve the ability of the system to detect imbalanced fraud data. The dataset
employed in this research was sourced from a Kaggle repository
[15]
and includes attributes such as the
transaction hour, amount, category, state, user age, and fraud risk. These attributes make it possible to perform
a behavior analysis of the transactions, including their temporal behavior, frequency, and value-based
anomalies. The data were preprocessed in a manner that involved scaling, encoding, and balancing.
The main aim of this study is to develop a high-performance fraud detection model capable of distinguishing
between legitimate transactions and mule account activities. The performance of the proposed model is
evaluated using standard classification metrics such as accuracy, precision, recall, F1 score, confusion matrix,
and receiver operating characteristic–area under the curve (ROC–AUC). The target ROC–AUC score is above 0.9,
indicating strong discriminatory ability. To enhance practical applicability, the trained model is integrated into
a Streamlit-based web application that enables real-time predictive analytics. Through this application, users
can input transaction parameters and instantly receive predictions regarding the risk of fraud. The deployment
of the machine learning model within the web application demonstrates its potential use in real-world financial
monitoring systems.
2. Literature review
Few studies have investigated the application of machine learning for the detection of fraud in digital payments.
Traditional machine learning models such as support vector machines (SVMs), decision trees, logistic
regression, and random forests were used to detect anomalies in the data. Traditional machine learning models
require labeled data to train the models to learn patterns of legitimate and fraudulent activities. Traditional
machine learning models have shown moderate results, with an average accuracy and F1 scores of 80–90% on
financial datasets. Traditional machine learning models perform poorly on highly imbalanced fraud datasets
and tend to have higher false positive rates without the use of sophisticated resampling methods.
[16]
2.1 UPI-specific fraud detection studies
Research in the area of fraud detection in the UPI environment has recently become popular at a rapid pace and
has consequently given rise to fraud-related issues. Various studies have been conducted in the past few years
to explore the use of ML-based solutions for UPI fraud detection on the basis of transactional parameters and
evaluation metrics such as accuracy, precision, recall, F1 score, and ROC-AUC.
For instance, studies conducted using random forest and SVM classifiers on UPI transactions have shown the
accuracy and recall of classification to be indicative of the efficiency of ML-based solutions over rule-based
solutions.
[17,18]
Various studies have conducted comparative analyses using algorithms such as logistic
regression, support vector machine (SVM), and gradient boosting to evaluate their relative efficiency on the
basis of performance metrics.
[19,20]
These studies indicate that ensemble methods generally outperform
individual classifiers in terms of the ROC-AUC and F1 score.
Another gradient boosting algorithm, CatBoost, has also been used successfully on UPI fraud datasets, and it has
shown high AUC scores, which indicate a strong ability to distinguish between fraudulent and genuine
transactions on categorical data.
[21]
These recent studies, which are UPI focused, confirm once again that ML
algorithms perform better than threshold rules do.
2.2 Advanced approaches and hybrid methods
In addition to traditional ML, advanced methods that combine deep learning, transformers, and federated
learning have been suggested to improve detection results even further. A more recent method that combined
causal inference, transformers, and federated learning reported a precision and recall of 80–90%, which
outperformed traditional baselines on UPI datasets.
[22]
Other systematic literature reviews that have examined
digital payment fraud detection in general suggest that neural networks such as Long Short-Term Memory
(LSTM) and convolutional neural networks (CNNs) can detect fraud with accuracies above 99% when used on
sequential transaction data.
[23]
These hybrid and deep learning methods overcome the shortcomings of
traditional ML by modeling the temporal dynamics of transactions and the nonlinear interactions of features.