Red Teaming: How Ethical Hackers Are Exploiting Payment Systems

[Professor]

Abstract: Description of the methodology used by legal pentesters who simulate carder actions to test the resilience of banking applications, APIs, and infrastructure. Testing phases: reconnaissance, analysis, exploitation, and post-analysis.

Introduction: A drill where the enemy always wins (so that the defense wins)​

Imagine you have a seemingly impenetrable fortress. You're confident in its walls, moats, and guards. But how can you test it in reality? You can wait for a real siege — and then the cost of a mistake will be catastrophic. Or you can hire the best siege experts from outside, give them carte blanche, and say, "Try to take this fortress by any means necessary. Find the weak link before the real enemy does." This is exactly how red teaming

works in the financial sector. It's not just checking boxes on a vulnerability list. It's a full-fledged simulation of a real attack by a determined and resourceful adversary — be it carders, hacktivists, or cyberspies — on the live, functioning infrastructure of a bank, payment gateway, or fintech company. The goal of the red team is not to cause harm, but to find a flaw. Not to disrupt operations, but to strengthen them. This is the highest form of security awareness, based on the principle that to protect a system, you must be able to think like someone who wants to break it.

Chapter 1: Who are "ethical hackers" and what is the philosophy of Red Teaming?​

A Red Team is a group of highly qualified cybersecurity specialists, authorized and contracted by the client. Their mandate is to simulate the tactics, techniques, and procedures (TTPs) of real attackers, without being limited to pre-determined scenarios.

The key difference from a traditional pentest is:

• Penetration testing: "Check our mobile app and website for vulnerabilities against this list." Focus on depth within a given perimeter.
• Red Teaming: "Imagine you're a cybercriminal group whose goal is to steal our clients' card data or disable a payment gateway. Act like them. Use any vectors: employee phishing, vulnerabilities in partner APIs, physical intrusion into the office. Your goal is to reach critical assets." Focus on breadth, realism, and operating under uncertainty.

Their work is legal, ethical, and subject to strict Rules of Engagement, which define prohibited actions (such as DDoS attacks on production) and emergency communication channels.

Chapter 2. Methodology: Four Phases of a Realistic Attack Simulation​

The Red Team's work simulates the full cycle of a cyberattack, known as the Cyber Kill Chain.

Phase 1: Reconnaissance​

Objective: Gather maximum information about the target without attracting attention.
Red Team Actions:

• OSINT: Analysis of publicly available information: company websites, job postings (which may reveal technologies used), employee LinkedIn profiles, technical forums where developers seek help, old backups on unprotected servers.
• Active reconnaissance: Scanning the network perimeter for open ports, outdated services, and subdomains. Gathering information about technology stacks (CMS, frameworks, and analytics systems).

An example for the financial sector: A search on GitHub (or similar sites) by bank name might accidentally reveal a repository with "test" API keys or fragments of configuration files posted by an inattentive developer.

Phase 2: Weaponization & Delivery – "Preparing for Invasion"​

Objective: Based on intelligence, develop penetration methods.
Actions:

• Developing phishing campaigns: Creating emails that are highly personalized for the target audience (tech support, accounting, and developers). The email can be disguised as a notification from an internal HR department or vendor.
• Exploit discovery and creation: Analysis of discovered vulnerabilities (e.g., in the partner web interface) and preparation of tools for their exploitation.
• Choosing a delivery vector: How to deliver the "payload" — via email, through a compromised partner site, or via a USB drive planted in the smoking area near the office?

Phase 3: Exploitation, Installation, C2 & Lateral Movement (Breakthrough and Beachhead Establishment)​

Objective: Overcome the perimeter, gain a foothold within the network, and move toward the target.
Actions:

• Hacking: Using exploits to gain initial access (e.g. through a vulnerability in a web application or intercepting an employee's credentials through phishing).
• Establishing control: Introducing remote access tools (RAT) into the compromised system, disguised as legitimate processes.
• Privilege escalation: Elevation of privileges within a system (from user to administrator) through OS vulnerabilities or configuration errors.
• Lateral Movement: Using stolen passwords, hashes, or vulnerabilities to move from one workstation to another, from server to server, aiming to reach critical systems - card data database (CHD) servers, card issuing systems, payment processing core (Payment Switch).

The key point for the Red Team: Operate as stealthily as possible, like a real APT adversary, bypassing intrusion detection systems (IDS/IPS) and antiviruses.

Phase 4: Actions on Objectives & Post-Exploitation – Mission Accomplished​

Objective: To prove that a critical asset may be compromised and to gather evidence for reporting.
Actions:

• Achieving the goal: The "Red Team" doesn't steal actual data, but rather demonstrates the ability. This could involve creating a test file marked "PAN DATABASE ACCESS GRANTED" on a secure server or sending a control signal from the system responsible for processing transactions.
• Evidence collection: Screenshots, logs, file hashes — anything that proves the fact of penetration and the depth of compromise.
• Post-exploitation and impact analysis: Assess what other systems may have been affected and what data may have been available.

Chapter 3. Focus on Finance: What are banks and payment systems looking for?​

The Red Team in the financial sector looks at business logic and specific assets:

1. Bypassing Application Business Logic: Is it possible to transfer an amount greater than the limit by manipulating mobile banking API requests? Or cancel an already completed transfer?
2. Attacks on authorization and authentication systems (AuthN/AuthZ): Is it possible to forge a transaction's cryptographic signature? Bypass 3-D Secure? Perform an operation on behalf of another user by changing the parameters in the request (IDOR — Insecure Direct Object References)?
3. Chains of trust between systems: The attack is not on the bank's core, but on a less secure partner (vendor) with access to its API. For example, through a scoring system or notification delivery service.
4. Insider Threats and Social Engineering: How Effectively Do Employees Protect Their Credentials? Is it Posing as an "IT Help Desk" Technician to Gain Physical Access to a Server Room?
5. Card Data Security (PCI DSS Scope): Are all systems handling PANs properly isolated (segmented)? Is it possible to access the cardholder data environment (CDE) from the office network?

Chapter 4. Result: Not a Report, but a Transformation​

The Red Team's work yielded not just a list of vulnerabilities, but a narrative of a real attack — a gripping story of how, starting with an innocuous email, they reached the heart of the financial system.

The company's key findings:

1. Detecting unknown threat vectors: Those that security architects didn't think about.
2. Blue Team (defenders) effectiveness assessment: How quickly and accurately did internal SOC analysts detect Red Team activity? Were they able to respond appropriately?
3. Incident Response Process (IRP) Testing: Was the plan implemented? Was the communication effective? How quickly was the threat neutralized?
4. A Qualitative Leap Forward in Safety Culture: When management and employees clearly see how their actions (or inactions) can lead to disaster, it is a powerful incentive for change.

Conclusion: The Noble Role of the "Adversary"​

Red Teaming is the highest form of security partnership. It recognizes that no system is perfect, and the most honest way to test it is to subject it to an intellectual, professional stress test.

The "ethical hackers" in red teams are not former criminals. They are engineers, cryptographers, sociologists, and strategists who have dedicated their talents not to hacking, but to strengthening. Their thinking is the same "carder" analytical mindset we discussed in the first article of this series, but focused solely on creation.

Thanks to their work, banks and fintechs can rest easier knowing that their security has been tested in conditions as close to real-world as possible. And we, the clients, can be a little more confident that our money and data are protected not on paper, but in the real, harsh digital world. Ultimately, Red Teaming is an investment in trust, the most valuable currency in the financial sector.