Credit Card Enumeration Attacks – Stealing From Your Accounts – 2024

Credit Card Enumeration Attacks – Stealing From Your Accounts

How Fraudsters Use Credit Card Enumeration Attacks to Steal Payment Data – and How to Protect Yourself or Your Business

How Scams Work – A SCARS Institute Insight

Author:
•  Tim McGuinness, Ph.D. – Anthropologist, Scientist, Director of the Society of Citizens Against Relationship Scams Inc.

Article Abstract

Fraudsters use enumeration attacks to systematically test combinations of credit card numbers, CVVs, and expiration dates by running small transactions, aiming to find valid card details.

These attacks often occur through merchants with weak fraud controls, allowing criminals to verify stolen card information and later conduct large-scale fraud.

To protect against such attacks, both businesses and cardholders must monitor for unusual transaction patterns, set strong fraud controls, and promptly address small unauthorized charges. Strengthening security practices like multi-factor authentication can help reduce the risk of these attacks.

Credit Cards Enumeration Attacks - Stealing From Your Accounts - 2024

How Fraudsters Use Credit Card Enumeration Attacks to Steal Payment Data – and How to Protect Yourself or Your Business

Fraudsters increasingly use enumeration attacks to steal payment data, exploiting legitimate businesses by methodically testing card numbers, expiration dates, and CVV codes through merchant payment systems. This is akin to picking a lock, one digit at a time. They often test small-dollar transactions to verify stolen card details before launching more extensive fraudulent activities.

Key Tactics Fraudsters Use to Steal from Credit Cards

  1. Enumeration Attacks: Fraudsters attempt multiple combinations of card details to find valid ones.
  2. Account Testing: Small transactions ($1–$2) test the validity of cards. Successful tests lead to large-scale fraud.
  3. Phishing or Merchant Account Takeovers: Criminals gain access to merchant accounts by phishing, taking over, or creating fake accounts.
  4. Clone Payment Devices: Fraudsters also use cloned payment terminals to bypass legitimate merchant channels.

According to VISA:

Threat actors are leveraging sophisticated technologies, like automated scripts and botnets, to amplify their card testing attacks, allowing them to exploit vulnerabilities at an unprecedented scale and speed. These attacks, known as enumeration attacks, inflict operational expenses and $1.1B annually in fraud losses, accounting for a significant portion of global fraud.

Enumeration can have lasting impacts on our VISA clients and there’s an immediate need for tools that can better detect and prevent these attacks in real-time, said Paul Fabara, Chief Risk and Client Services Officer at Visa.

Thirty three percent of enumerated accounts experienced fraud within five days of a fraudster obtaining access to their payment information.

How Credit Card Enumeration Attacks Work

Enumeration attacks are a form of payment fraud where criminals use trial-and-error methods to systematically test combinations of card details (like card numbers, CVVs, and expiration dates) through online payment systems. This method exploits weak or non-existent fraud detection mechanisms within a payment processing system, and fraudsters may only need a few valid pieces of data to succeed.

How the Attack Is Executed

    • Card Number Testing: Fraudsters start by acquiring partial or full card numbers, often from breaches or the dark web. They then attempt to “guess” additional information, such as CVV and expiration dates, by running multiple small transactions.
    • Using Merchant Systems: The fraudster tests these combinations through a legitimate merchant’s payment gateway, trying various expiration dates and CVVs until a valid combination is found. Automated bots are frequently used to speed up this process.
    • Small Transactions: The attackers often use small-dollar transactions (e.g., $1–$2) to avoid detection and ensure the card details are valid. Once validated, they move on to more substantial fraudulent purchases.

What Fraudsters Expect

    • Successful Matches: The ultimate goal of an enumeration attack is to identify valid card details that can then be exploited for larger fraud schemes, such as making significant online purchases or selling the card information.
    • Minimal Risk: Fraudsters expect to operate under the radar, using numerous merchants to distribute their attack and lessen the chances of detection. By testing small transactions across various platforms, they avoid triggering traditional fraud alerts.

How Cardholders Can Be Aware

    • Monitor Small Transactions: Cardholders should keep an eye on small, unfamiliar charges, which could indicate that their card details are being tested. Even a small transaction can be a red flag.
    • Set Up Alerts: Most banks allow customers to set up text or email alerts for any transactions, particularly international or online ones.
    • Report Suspicious Activity: If cardholders notice unauthorized charges, they should report them to their bank immediately to freeze the account and prevent further fraudulent use.

How Merchants Can Be Aware

Merchants can spot Enumeration Attacks by carefully monitoring their payment systems for unusual patterns and irregular transaction behavior. Here’s how they can detect attacks both in progress and after the fact:

Spotting Enumeration Attacks in Progress:

      • Unusual Transaction Patterns: A high volume of small, rapid transactions in quick succession from different cards can signal an attack. These attempts often involve microcharges of $1–$2, indicating fraudsters are testing combinations of card numbers, CVVs, and expiration dates.
      • High Decline Rates: A sudden spike in transaction decline rates, especially for small charges, may indicate that criminals are trying multiple invalid card details, hoping to find the right combination.
      • Unusual IP Addresses or Geolocations: Attackers may use bots or automated systems, which often result in multiple transactions coming from a single or a few unusual IP addresses that don’t match the expected locations of customers.
      • Repeated Usage of Similar Card Numbers: Fraudsters might increment or decrement card numbers slightly to identify valid combinations. If the merchant’s system spots patterns of numbers being tested with different CVV or expiration dates, this is a clear sign of enumeration attacks.

Identifying Enumeration Attacks After the Fact:

      • Transaction Logs Review: Conduct post-event reviews of transaction logs, focusing on declined transactions. A significant number of declines over a short period or across several merchant accounts can point to previous enumeration attacks.
      • Analysis of Fraud Chargebacks: Multiple chargebacks linked to small, successful transactions followed by larger fraudulent purchases can indicate that attackers successfully tested card details using enumeration.
      • Merchant Account Breaches: If the business sees a pattern of suspicious account behavior (e.g., account takeovers or unusual payment device setups), attackers may be targeting the system to exploit it for card testing.

By regularly reviewing transactions for these signs and implementing strong fraud prevention tools such as rate limiting, CAPTCHA, and two-factor authentication (2FA), merchants can better detect and block enumeration attacks before they cause substantial damage.

Protecting Against Enumeration Attacks

Both businesses and cardholders must remain vigilant. Implementing strong authentication measures, monitoring for unusual transaction patterns, and regularly reviewing credit or debit card statements can help mitigate the risk of being affected by enumeration attacks.

Summary: Know The Basics

  1. Strong Authentication: Ensure multi-factor authentication (MFA) for anyone accessing your payment systems.
  2. Monitoring Transaction Patterns: Keep a close eye on transaction anomalies, especially small-dollar amounts.
  3. Enforce Strict Fraud Controls: Implement strict limits and controls for small transactions to block account testing.
  4. Employee Training: Educate employees about phishing and social engineering techniques used to take over accounts.

By staying vigilant and adopting robust security practices, businesses can safeguard themselves from becoming unwilling participants in these fraud schemes.

Please Leave Us Your Comment
Also, tell us of any topics we might have missed.

Leave a Reply

Your comments help the SCARS Institute better understand all scam victim/survivor experiences and improve our services and processes. Thank you

Your email address will not be published. Required fields are marked *

Thank you for your comment. You may receive an email to follow up. We never share your data with marketers.

Recent Reader Comments

Important Information for New Scam Victims

If you are looking for local trauma counselors please visit counseling.AgainstScams.org or join SCARS for our counseling/therapy benefit: membership.AgainstScams.org

If you need to speak with someone now, you can dial 988 or find phone numbers for crisis hotlines all around the world here: www.opencounseling.com/suicide-hotlines

A Question of Trust

At the SCARS Institute, we invite you to do your own research on the topics we speak about and publish, Our team investigates the subject being discussed, especially when it comes to understanding the scam victims-survivors experience. You can do Google searches but in many cases, you will have to wade through scientific papers and studies. However, remember that biases and perspectives matter and influence the outcome. Regardless, we encourage you to explore these topics as thoroughly as you can for your own awareness.

SCARS Resources:

Other Cyber Resources

-/ 30 /-

What do you think about this?
Please share your thoughts in a comment below!

Legal Disclaimer:

The content provided on this platform regarding psychological topics is intended solely for educational and entertainment purposes. The publisher makes no representations or warranties regarding the accuracy or completeness of the information presented. The content is designed to raise awareness about various psychological subjects, and readers are strongly encouraged to conduct their own research and verify information independently.

The information presented does not constitute professional advice, diagnosis, or treatment of any psychological disorder or disease. It is not a substitute for professional medical or mental health advice, diagnosis, or treatment. Readers are advised to seek the guidance of a licensed medical professional for any questions or concerns related to their mental health.

The publisher disclaims any responsibility for actions taken or not taken based on the content provided. The treatment of psychological issues is a serious matter, and readers should consult with qualified professionals to address their specific circumstances. The content on this platform is not intended to create, and receipt of it does not constitute, a therapist-client relationship.

Interpretation and Definitions

Definitions

For the purposes of this Disclaimer:

  • Company (referred to as either “the Company”, “We”, “Us” or “Our” in this Disclaimer) refers to Society of Citizens Against Relationship Scams Inc. (registered d.b.a. “SCARS”,) 9561 Fountainbleau Blvd., Suit 602, Miami FL 33172.
  • Service refers to the Website.
  • You means the individual accessing this website, or the company, or other legal entity on behalf of which such individual is accessing or using the Service, as applicable.
  • Website refers to RomanceScamsNOW.com, accessible from https://romancescamsnow.com

Website Disclaimer

The information contained on this website is for general information purposes only.

The Company assumes no responsibility for errors or omissions in the contents of the Service.

In no event shall the Company be liable for any special, direct, indirect, consequential, or incidental damages or any damages whatsoever, whether in an action of contract, negligence or other tort, arising out of or in connection with the use of the Service or the contents of the Service. The Company reserves the right to make additions, deletions, or modifications to the contents on the Service at any time without prior notice.

The Company does not warrant this website in any way.

External Links Disclaimer

This website may contain links to external websites that are not provided or maintained by or in any way affiliated with the Company.

Please note that the Company does not guarantee the accuracy, relevance, timeliness, or completeness of any information on these external websites.

Errors and Omissions Disclaimer

The information given by SCARS is for general guidance on matters of interest only. Even if the Company takes every precaution to ensure that the content of this website is both current and accurate, errors can occur. Plus, given the changing nature of laws, rules, and regulations, there may be delays, omissions, or inaccuracies in the information contained on this website.

SCARS is not responsible for any errors or omissions, or for the results obtained from the use of this information.

Fair Use Disclaimer

SCARS may use copyrighted material that has not always been specifically authorized by the copyright owner. The Company is making such material available for criticism, comment, news reporting, teaching, scholarship, or research.

The Company believes this constitutes a “fair use” of any such copyrighted material as provided for in section 107 of the United States Copyright law.

If You wish to use copyrighted material from this website for your own purposes that go beyond fair use, You must obtain permission from the copyright owner.

Views Expressed Disclaimer

The Service may contain views and opinions which are those of the authors and do not necessarily reflect the official policy or position of any other author, agency, organization, employer, or company, including SCARS.

Comments published by users are their sole responsibility and the users will take full responsibility, liability, and blame for any libel or litigation that results from something written in or as a direct result of something written in a comment. The Company is not liable for any comment published by users and reserves the right to delete any comment for any reason whatsoever.

No Responsibility Disclaimer

The information on the Service is provided with the understanding that the Company is not herein engaged in rendering legal, accounting, tax, medical or mental health, or other professional advice and services. As such, it should not be used as a substitute for consultation with professional accounting, tax, legal, medical or mental health, or other competent advisers.

In no event shall the Company, its team, board of directors, volunteers, or its suppliers be liable for any special, incidental, indirect, or consequential damages whatsoever arising out of or in connection with your access or use or inability to access or use the Service.

“Use at Your Own Risk” Disclaimer

All information on this website is provided “as is”, with no guarantee of completeness, accuracy, timeliness or of the results obtained from the use of this information, and without warranty of any kind, express or implied, including, but not limited to warranties of performance, merchantability, and fitness for a particular purpose.

SCARS will not be liable to You or anyone else for any decision made or action taken in reliance on the information given by the Service or for any consequential, special, or similar damages, even if advised of the possibility of such damages.

Contact Us

If you have any questions about this Disclaimer, You can contact Us:

  • By email: contact@AgainstScams.org

PLEASE NOTE: Psychology Clarification

The following specific modalities within the practice of psychology are restricted to psychologists appropriately trained in the use of such modalities:

  • Diagnosis: The diagnosis of mental, emotional, or brain disorders and related behaviors.
  • Psychoanalysis: Psychoanalysis is a type of therapy that focuses on helping individuals to understand and resolve unconscious conflicts.
  • Hypnosis: Hypnosis is a state of trance in which individuals are more susceptible to suggestion. It can be used to treat a variety of conditions, including anxiety, depression, and pain.
  • Biofeedback: Biofeedback is a type of therapy that teaches individuals to control their bodily functions, such as heart rate and blood pressure. It can be used to treat a variety of conditions, including stress, anxiety, and pain.
  • Behavioral analysis: Behavioral analysis is a type of therapy that focuses on changing individuals’ behaviors. It is often used to treat conditions such as autism and ADHD.
    Neuropsychology: Neuropsychology is a type of psychology that focuses on the relationship between the brain and behavior. It is often used to assess and treat cognitive impairments caused by brain injuries or diseases.

SCARS and the members of the SCARS Team do not engage in any of the above modalities in relationship to scam victims. SCARS is not a mental healthcare provider and recognizes the importance of professionalism and separation between its work and that of the licensed practice of psychology.

SCARS is an educational provider of generalized self-help information that individuals can use for their own benefit to achieve their own goals related to emotional trauma. SCARS recommends that all scam victims see professional counselors or therapists to help them determine the suitability of any specific information or practices that may help them.

SCARS cannot diagnose or treat any individuals, nor can it state the effectiveness of any educational information that it may provide, regardless of its experience in interacting with traumatized scam victims over time. All information that SCARS provides is purely for general educational purposes to help scam victims become aware of and better understand the topics and to be able to dialog with their counselors or therapists.

It is important that all readers understand these distinctions and that they apply the information that SCARS may publish at their own risk, and should do so only after consulting a licensed psychologist or mental healthcare provider.

SCARS IS A DIGITAL PUBLISHER AND DOES NOT OFFER HEALTH OR MEDICAL ADVICE, LEGAL ADVICE, FINANCIAL ADVICE, OR SERVICES THAT SCARS IS NOT LICENSED OR REGISTERED TO PERFORM.

IF YOU’RE FACING A MEDICAL EMERGENCY, CALL YOUR LOCAL EMERGENCY SERVICES IMMEDIATELY, OR VISIT THE NEAREST EMERGENCY ROOM OR URGENT CARE CENTER. YOU SHOULD CONSULT YOUR HEALTHCARE PROVIDER BEFORE FOLLOWING ANY MEDICALLY RELATED INFORMATION PRESENTED ON OUR PAGES.

ALWAYS CONSULT A LICENSED ATTORNEY FOR ANY ADVICE REGARDING LEGAL MATTERS.

A LICENSED FINANCIAL OR TAX PROFESSIONAL SHOULD BE CONSULTED BEFORE ACTING ON ANY INFORMATION RELATING TO YOUR PERSONAL FINANCES OR TAX RELATED ISSUES AND INFORMATION.

SCARS IS NOT A PRIVATE INVESTIGATOR – WE DO NOT PROVIDE INVESTIGATIVE SERVICES FOR INDIVIDUALS OR BUSINESSES. ANY INVESTIGATIONS THAT SCARS MAY PERFORM IS NOT A SERVICE PROVIDED TO THIRD-PARTIES. INFORMATION REPORTED TO SCARS MAY BE FORWARDED TO LAW ENFORCEMENT AS SCARS SEE FIT AND APPROPRIATE.

This content and other material contained on the website, apps, newsletter, and products (“Content”), is general in nature and for informational purposes only and does not constitute medical, legal, or financial advice; the Content is not intended to be a substitute for licensed or regulated professional advice. Always consult your doctor or other qualified healthcare provider, lawyer, financial, or tax professional with any questions you may have regarding the educational information contained herein. SCARS makes no guarantees about the efficacy of information described on or in SCARS’ Content. The information contained is subject to change and is not intended to cover all possible situations or effects. SCARS does not recommend or endorse any specific professional or care provider, product, service, or other information that may be mentioned in SCARS’ websites, apps, and Content unless explicitly identified as such.

The disclaimers herein are provided on this page for ease of reference. These disclaimers supplement and are a part of SCARS’ website’s Terms of Use. 

All original content is Copyright © 1991 – 2023 Society of Citizens Against Relationship Scams Inc. (Registered D.B.A SCARS) All Rights Reserved Worldwide & Webwide. Third-party copyrights acknowledge.

U.S. State of Florida Registration Nonprofit (Not for Profit) #N20000011978 [SCARS DBA Registered #G20000137918] – Learn more at www.AgainstScams.org

View the claimed and or registered indicia, service marks, and trademarks of Society of Citizens Against Relationship Scams Inc., All Rights Reserved Worldwide

Contact the law firm for the Society of Citizens Against Relationship Scams Incorporated by email at legal@AgainstScams.org

Share This Information - Choose Your Social Media!

Leave A Comment

Your comments help the SCARS Institute better understand all scam victim/survivor experiences and improve our services and processes. Thank you


Thank you for your comment. You may receive an email to follow up. We never share your data with marketers.