Machine learning for fraud detection:
essentials, use cases, and guidelines

Machine learning for fraud detection: essentials, use cases, and guidelines

September 26, 2023

ML-based vs rule-based fraud detection

ML-enabled anomaly detection applications differ from traditional software in terms of detection technique:

UserTransactionsML modelOngoing model fine-tuningPatterns anomaliesDetectionMachine LearningFraudsterFraudRulesHigher frequencyAddress mismatchOver limitDetectionRule Based

ML-based fraud detection

  • ML solutions autonomously identify and use more complex and variable rules than traditional systems. To do so, ML algorithms process data on past fraud cases, discover patterns and relationships between data points, and build models trained to identify those patterns once they recur in future datasets.
  • ML systems can predict imminent criminal actions by identifying anomalies, namely subtle and unconventional behavioral patterns that humans would probably overlook but that still deviate from the norm, which could be clues to upcoming fraud.
  • ML-powered solutions improve with experience, refining their models over time as they process new data, including unmapped data points. So, if they encounter new fraud scenarios, machine learning-based anomaly detection systems will quickly adapt to such threats, automatically integrating and updating the existing rules without human intervention.
Example
The fraud detection system of an ecommerce platform runs into a suspicious credit card transaction that doesn't fit its user’s behavioral patterns based on multiple subtle parameters, such as the product pages browsed before placing an order.

Rule-based fraud detection

  • Traditional rule-based solutions follow an "if/then" logic and trigger a response when a predefined condition is violated.
  • These tools must be manually instructed to detect fraud cases by compiling libraries with hundreds of rules.
Example
The fraud detection system of a bank flags supposed customers who use credit cards in unusual locations, or increase their payment frequency.

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Technical overview of ML for fraud detection

ML approaches

Do machines need human intervention to learn, or can they just observe the surrounding reality? The main approaches to training machine learning algorithms are supervised, unsupervised, and reinforcement learning, depending on the degree of human involvement and control over the ML training process.

Supervised learning

ML-based fraud detection systems are trained with large amounts of labeled data, previously annotated with certain labels describing its key features. This can be data from legitimate and fraudulent transactions described with "fraud" or "non-fraud" labels, respectively. These labeled datasets, which require rather time-consuming manual tagging, provide the system with both the input (transaction data) and the desired output (groups of classified examples), allowing algorithms to identify which patterns and relationships connect them and apply such findings to classify future cases.

Unsupervised learning

These algorithms are fueled with unlabeled transaction data and have to autonomously group these transactions into different clusters based on their similarities (shared behavioral patterns) and differences (typical vs unusual patterns which can correspond to fraudulent activity). This approach, typically associated with deep learning, is computationally demanding but can be the only choice when facing fraud attempts that have never been met before and therefore unlabelled.

Reinforcement learning

This trial-and-error approach involves multiple training iterations in which the algorithm performs a fraud detection task in different ways several times until it can accurately identify fraudulent and non-fraudulent attempts. Since it does not require labeled inputs, reinforcement learning can be applied without prior knowledge of the current fraud scenario. However, it requires considerable computing power.

Input Raw DataAlgorithmModel TrainingLabeled dataProcessingClassificationOutputSupervised learningInput Raw DataAlgorithmInterpretationUnannotated training data setUnknown outcomeProcessingClustersOutputUnsupervised learning

Scheme title: Supervised vs unsupervised learning

Data source: medium.com — An Executive’s View: Introduction to Machine Learning

Machine learning vs deep learning

Experts generally distinguish between machine learning as a whole and its more advanced branch, known as deep learning.

Machine learning

A subset of AI focusing on systems that can learn and improve with experience. Identifying patterns and anomalies is one of their most common tasks and a key enabler for fraud detection. “Traditional” ML solutions can be trained with a relatively small amount of data and don’t need substantial computational power, at least compared to deep learning-based software.

Deep learning

A machine learning method typically associated with complex sets of algorithms known as deep neural networks. Such structures, comprising connected layers of artificial neurons that mimic the human brain, can process data flowing from one layer to the next and spot the most subtle patterns and features hidden within an immense amount of data points. This particular process makes neural networks very effective in detecting fraud, but it also requires enormous computational power and large data sets for proper training.

ML algorithms

Identifying the best algorithm or ensemble of algorithms to perform fraud-related data analysis can be a challenging task, as their performance can depend on the scenario in which we operate. Here are some options to consider:

Logistic regression

A supervised learning algorithm which calculates the probability of one event out of two alternatives, such as "fraud" and "non-fraud" based on a set of relevant parameters.

Decision tree

Another algorithm of the supervised learning subset is a tree-like decision-making model in which every bifurcation represents the analysis of a certain metric or condition (spending threshold, location, etc.) to determine whether an operation is fraudulent.

Random forest

A combination of several decision trees to further expand the amount of data types and conditions examined and identify non-linear relations among multiple variables.

Support vector machine

Several systems rely on this supervised learning algorithm for credit card fraud detection because of its excellent performance with large datasets despite it being computationally demanding.

K-nearest neighbor

This supervised learning algorithm, which proves quite accurate but difficult to interpret when making a certain decision, can frame the nature of an event (be it fraud or non-fraud) by comparing it with similar occurrences recorded in the past.

Neural networks

Complex, multi-layered architecture and superior big data analysis capabilities make neural networks the go-to algorithms when it comes to spotting non-linear relations and dealing with unprecedented fraud scenarios through supervised, unsupervised and reinforcement learning.

Machine learning in top fraud scenarios

Machine learning can be deployed to keep fraudsters and cybercriminals at bay in a variety of scenarios. Let’s take a look at some popular use cases of this technology.

Machine learning in top fraud scenarios

Financial institutions have come to understand the synergistic potential between the stock market and machine learning and the benefits of predictive analytics in finance, considering the large sums involved and the required compliance with increasingly strict regulations.

ML-driven systems can help prevent financial fraud, such as churning, spoofing, and wash trading, by spotting anomalies in stock traders' activity and cross-checking transactions and brokers' data to detect inconsistencies in the information provided.

Applying machine learning in banking has proved useful to track anomalous transactions that could be a sign of criminal activity, such as large sums of money exchanged among a group of newly-established companies registered in tax havens.

Machine learning models can be trained with data relating to three possible scenarios: lawful transactions, money transfers flagged as suspicious by bank alert systems, and potential money laundering cases reported to the authorities. For each case, machine learning systems analyze the senders’ and receivers' background or their previous transaction histories. This way, they can spot the same patterns once they recur in future scenarios and therefore distinguish between legitimate activities and criminal actions.

Electronic payment fraud represents a widespread crime taking many forms and encompassing almost any industry, from banking to ecommerce. However, machine learning systems in retail have a good chance of containing this escalation by detecting abnormal account behavior that could be a sign of fraud. Some of the factors to consider are a growing transaction frequency (especially to purchase premium goods), payment on a card carried out significantly before the due date, associations with different high-risk accounts, and multiple payment methods added in a short time.

Machine learning-driven systems for payment fraud detection can also update card users' behavioral profiles after each transaction, making future predictions more precise and avoiding false positives.

Another type of crime strictly connected to payment card fraud and remarkably widespread in many scenarios, including fraudulent loan applications and ecommerce scams, is identity theft. This involves a scammer exploiting the personal information of another individual, including their name and credit card number, without their consent to commit a crime. To deal with this kind of fraud, we can count once again on machine learning-driven analysis of users' habits and transaction data.

Furthermore, we can leverage machine learning-powered computer vision to analyze identity documents or add additional verification mechanisms such as face recognition and biometrics.

Machine learning solutions can also strengthen fraud detection in the insurance sector, especially in health insurance. Algorithms can identify false and duplicate claims, pointing out a customer who reported an incorrect diagnosis or exaggerated medical coverage costs.

One of the most valuable machine learning techniques in healthcare is natural language processing, which ensures an in-depth analysis of unstructured data such as medical reports. These solutions leverage machine learning to scan documents written by doctors, insurers, or clients, searching for suspicious inconsistencies.

Public authorities can use machine learning capabilities in identifying unusual patterns to enhance audit and tax compliance. For example, ML can examine the general ledger for anomalous entries which could be the signs of attempted fraud.

Algorithms can spot a wide range of clues easier and faster than human auditors, taking into account various parameters. These include monthly variations in companies' gross sales, relations among different taxpayers, inconsistencies among purchases, or the itemized deductions in an income peer group.

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Real-world examples of ML for fraud detection

Capgemini reported that customers adopting its ML-enabled CPP Fraud Analytics software for fraud detection and prevention have benefited from an increase in detection rate between 50% and 90% and a reduction in investigation time for each fraud case up to 70%. The solution relies on an ensemble of technologies and approaches, including both rule-based fraud detection and neural network-powered pattern analysis, to perform tasks ranging from KYC operations to anti-money laundering and credit card fraud.
LendingBankingCardsOther relationshipsCustomer view internal dataUnstructured data – social media, call centers etc.Credit bureau, fraud vendors, watch lists, Mkt & reference dataCustomer view external dataInternetATMPOSPhone bankingOther channels/tradesCustomer view transaction dataBig dataArtificial neural networks/pattern recognitionAccount opening decisioningAdaptive analytics, rule based modelsCustomer level fraud manage-mentOffline entity link analysisBiometricsTransaction fraud monitoring3d secureCounterfeit measuresDevice trackingTokenizationFraud monitoring & detectionDecisionsAlert managementDataNotificationsCase managementVisualization/reports/dashboards