Secure Checkout: How to Spot A Credit Card Skimmer

According to Securi, credit card skimming malware was detected on 4,614 websites in the first half of 2023. These detections were spread across 87 distinct credit card skimmer variants and impacted popular CMSs like WordPress, Magento and OpenCart.

This alarming observation highlights the critical need for businesses to enhance their cybersecurity defenses beyond using the top antivirus services.

E-skimming, aka web skimming, formjacking, or magecart attacks, poses a grave danger to businesses. Cybercriminals leverage weaknesses in third-party providers to infiltrate e-commerce websites, embedding malicious code that allows them to steal crucial payment data such as credit card details at checkout.

According to a report by Gemini Advisory, these attacks can go undetected for an average of 171 days, leaving so-called secure payment systems vulnerable and customer data at risk.

So, how to spot a credit card skimmer?

This article explores the potential impact of skimming attacks and the importance of robust security measures for secure payment processing. We will guide you on how to prevent credit card skimming and implement controls to protect your e-commerce checkout pages.


Key Takeaways

  • When cybercriminals successfully steal credit card details through e-skimming attacks, customers become vulnerable to fraudulent transactions and expose their personal information for potential identity theft. To safeguard businesses and customers alike, organizations must take immediate action.
  • An e-commerce company faces an average data breach cost of $3.86 million, emphasizing the critical need for businesses to enhance cybersecurity defenses. 
  • E-skimming, also known as magecart attacks, poses a significant danger to businesses by infiltrating e-commerce websites to steal payment data during checkout.
  • Skimming attacks can remain undetected for an average of 171 days, leaving payment systems vulnerable and customer data at risk of identity theft and fraudulent transactions.
  • Implementing continuous monitoring, intrusion detection systems, and proactive vulnerability assessments are essential to safeguard e-commerce checkout pages from skimming attacks.
  • Adopting PCI-DSS standards, utilizing secure hosting services, implementing HTTPS encryption, and regularly updating software is crucial to protecting customer data, maintaining trust, and preserving business reputation.

What Is Skimming?

The web skimming attack, commonly called magecart, poses a significant threat to businesses relying on online payment processing systems.

This sophisticated cyberthreat targets vulnerable payment platforms, whether managed by third-party vendors or in-house by retailers.

Malicious actors employ intricate techniques to inject malicious scripts into websites, enabling them to intercept and siphon off customers’ payment data during critical checkout.

Types of Skimming

Card skimming is a significant threat to businesses and consumers, with various insidious methods employed by cybercriminals.

These include physical manipulation of point-of-sale terminals and ATMs and the stealthy digital skimming of online checkout pages.

In ATM attacks, criminals often use deceptive facades that mimic the originals, making it difficult to spot if there’s a potential attack in progress. This deceptive nature enables the fraudster to capture sensitive card data covertly.

The introduction of the recent shimming attacks, where an ultra-slim device is discreetly inserted into the card slot, represents a more advanced and difficult-to-detect form of skimming.

Such sophisticated operations can remain undetected for extended periods, resulting in substantial financial losses for banks and individuals.

The Mechanics of Web Skimming Attacks

Web skimming or digital skimming attacks breach website payment pages to steal users’ credit card details and personal data during transactions.

Protect against these attacks by updating software, using secure payment gateways, and monitoring website activity for suspicious behavior. Regular security audits and user awareness training are crucial. Stay vigilant to safeguard sensitive information and maintain trust with customers.

Skimming Attack Processes

  1. Gaining Access

    Attackers infiltrate websites through server breaches or compromised infrastructure to implant skimmers. Additionally, they exploit weaknesses in third-party providers’ systems to gain unauthorized access.
  2. Data Collection

    Using sophisticated techniques, cybercriminals embed malicious code disguised within seemingly harmless code to intercept and steal sensitive data entered into the website’s form fields, compromising user privacy and security.
  3. Sideloading and Chain-Loading Attacks

    Attackers often employ legitimate software or popular plugins as a guise to infiltrate a user’s device, strategically planting malware to capture and exploit sensitive information stealthily.
  4. Trusted Cloud-Hosted Skimming Attacks

    Attackers strategically exploit vulnerabilities in cloud-based services, such as web hosting platforms, to infiltrate websites with malicious code surreptitiously. This insidious tactic allows them to compromise sensitive data and disrupt online operations.
  5. Public Wi-Fi Skimming Attacks

    Exploiting unsecured public Wi-Fi networks allows cybercriminals to intercept sensitive data entered by unsuspecting users on compromised websites, posing significant data security and privacy risks.
  6. E-commerce Skimming Attacks

    Cybercriminals target online stores by injecting sophisticated malicious code into vulnerable checkout pages and stealthily harvesting sensitive credit card details and personal information of unsuspecting customers.
  7. Self-Cleaning and Stealth Data Skimming Attacks

    Crafted to evade detection, malicious code often self-deletes post-data theft or conceals its existence on websites, making it challenging for businesses to identify and combat effectively.

    How to Spot a Credit Card Skimmer? Web Skimming Protection

    Business owners must establish a basic multi-layered defense strategy to safeguard sensitive data against skimming threats directed at online credit card payments.

    Continuous monitoring, including thorough vulnerability scans, comprehensive risk evaluations, and simulated penetration testing exercises, is critical to pinpointing and addressing any vulnerabilities within the cardholder data environment (CDE).

    By performing these tests, organizations comprehensively understand their CDE and critical systems, enabling proactive identification and resolution of vulnerabilities.

    Intrusion detection systems (IDS) and intrusion prevention systems (IPS) enhance security, providing real-time detection and preventing unauthorized access attempts.

    By adopting a proactive approach to staying one step ahead of cybercriminals, businesses can maintain the integrity of their secure checkout processes, thwart potential data breaches, and safeguard their reputation and assets.

    How to Prevent Skimming and Ensure Secure Checkout

    5 Best Practices to Prevent Skimming

    Keep Software Up-to-Date

    Continuously updating software is essential to safeguard against evolving web skimming attacks. Regular updates ensure patches for vulnerabilities, enhancing overall cybersecurity defenses.

    Use Secure Hosting

    Utilize secure hosting services to safeguard your website against cyberthreats—partner with reputable web hosting platforms that uphold industry-leading security protocols to protect sensitive customer data.

    Implement HTTPS Encryption

    HTTPS encryption is crucial for safeguarding sensitive information between your website and customers. This industry-standard security measure ensures data integrity and confidentiality, protecting against potential cyberthreats.

    Monitor Suspicious Activity

    It’s crucial to regularly monitor your website for any unusual signs that could indicate a potential security breach.

    Be vigilant for unexpected changes to your website’s code, unfamiliar files, or abnormal traffic patterns that could signal the presence of unauthorized access or malicious activity.

    By staying proactive and conducting routine checks, you can protect your customer’s sensitive information and maintain the integrity of your online payment processes.

    Implement Security Protocols

    Implementing security protocols, including two-factor authentication using biometric verification or SMS codes, enforcing strong password policies with regular updates and complexity requirements, and implementing access controls based on roles and permissions for in-house and remote users, are essential to protect your website.

    These protocols safeguard against unauthorized access and provide layers of defense against potential cyberthreats, ensuring the integrity and confidentiality of sensitive data within your system.

    Contractual Requirements to Safeguard E-Commerce Website Security

    It’s worth mentioning that businesses processing transactions through major payment networks like Visa, Mastercard, American Express, Discover, JCB, and UnionPay must comply with the latest PCI DSS version 4.0 as part of their contractual obligations.

    This stringent standard integrates detailed protocols to fortify online checkout processes.

    Noteworthy for e-commerce operators are sub-requirements 6.4.3 and 11.6.1 under requirements 6 and 11, emphasizing enhanced security measures for secure payment gateways.

    Code Reviews and Secure Software Practices

    Sub-requirement 6.4.3 underscores the critical need for businesses to conduct comprehensive code reviews as part of their pre-production application release protocol.

    Through consistent code reviews, organizations can detect and rectify coding weaknesses early in development, reducing the likelihood of vulnerabilities being exploited and incorporating robust change control procedures and keeping a detailed inventory of all payment page scripts further bolsters proactive security defenses, safeguarding against potential cyberthreats and ensuring secure customer checkout processes.

    Detection of Unauthorized Changes

    Sub-requirement 11.6.1 is crucial as it emphasizes the swift identification of any unauthorized alterations to payment pages. Such changes can open the door to data breaches, putting sensitive information at risk and potentially compromising transactions.

    Organizations must implement robust mechanisms for detecting changes and tampering to meet this requirement.

    This includes implementing secure scripts and HTTP headers that prevent skimming attacks and significantly reduce the likelihood of fraudulent activities occurring during checkout.

    By proactively monitoring and promptly addressing any unauthorized modifications, businesses can safeguard their customers’ payment data and uphold the security of their online transactions.

    Technical Solutions to Securing E-Commerce Checkout Pages

    A data breach investigation report by Verizon in 2021 identified that 71% of organizations faced security breaches, primarily targeting web applications.

    Simply relying on traditional security measures like web application firewalls (WAFs) might fall short. Implementing innovative client-side solutions for real-time script monitoring and browser-level protection is crucial to effectively combat evolving threats and prevent data exfiltration.

    By adopting configurable code security policies, website security can be significantly strengthened, eliminating complexities while advancing protection protocols. Client-side security software provides a customized approach to safeguarding e-commerce checkout pages, catering to the specific security needs of businesses.

    By utilizing this solution, companies can fortify their payment pages against script-based attacks, align with PCI DSS v4.0 standards, and ensure the integrity and security of transactions through features like script validation, tamper detection, and detailed logging.

    Vendor, Scripts & Compliance Tracking

    Client-side security solutions offer comprehensive transparency by displaying a detailed inventory of vendors and scripts active on the payment page, along with their compliance status.

    This proactive approach ensures the authentication and secure operation of all running scripts, effectively mitigating risks to customer data.

    Tamper Detection & Prompt Action

    In addition to tamper detection mechanisms, implementing real-time monitoring tools and regular security audits can further strengthen the defense against cyberthreats.

    By staying vigilant and proactive, businesses can ensure a secure checkout process, instilling customer trust and loyalty.

    Comprehensive Protection for Compliance

    A robust client-side solution provides real-time visualization and monitoring of script behavior and ensures superior security for dynamic and frequently changing scripts.

    By offering browser-level protection, it surpasses the limitations of traditional web application firewalls in preventing data exfiltration. Configurable code security policies (CSPs) empower users with intuitive control, enhancing website security without complex configuration.

    The Bottom Line

    Business owners must take decisive action to safeguard their e-commerce checkout pages from the escalating threat of skimming attacks. By implementing continuous monitoring, intrusion detection systems, and proactive vulnerability assessments, they can maintain the integrity of their secure checkout processes.

    Utilizing secure hosting services, HTTPS encryption, and regularly updating software significantly reduces the risk of data breaches. Adhering to PCI-DSS and strengthening security defenses is crucial for businesses to protect their customer’s sensitive information, maintain trust, and preserve their reputation and assets.

    In the rapidly evolving digital landscape, a proactive and vigilant approach to cybersecurity is no longer optional—it’s essential.


    How can I tell if a checkout page is secure when I shop online?

    What does secure checkout mean?

    What does a credit card skimmer look like?


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    John Meah
    Cybersecurity Expert

    John is a skilled freelance writer who combines his writing talent with his cybersecurity expertise. He holds an equivalent level 7 master's degree in cybersecurity and a number of prestigious industry certifications, such as PCIP, CISSP, MCIIS, and CCSK. He has spent over two decades working in IT and information security within the finance and logistics business sectors. This experience has given John a profound understanding of cybersecurity practices, making his tech coverage on Techopedia particularly insightful and valuable. He has honed his writing skills through courses from renowned institutions like the Guardian and Writers Bureau UK.