Skip to content

Pentesting the Financial Vault: My Journey hacking into Top Fintechs

  • by

Greetings, cybersecurity enthusiasts! With over 4 years entrenched in the fintech sector, I’ve had the privilege to test the digital fortresses of some of the big banks and financial institutions. Add to that, 6+ years in the thrilling realm of bug bounties, and you could say I’ve seen a trick or two. Today, I’m pulling back the curtain to reveal my approach when targeting fintech applications. In an age where every transaction has a digital heartbeat, ensuring the security of these financial marvels is not just essential, it’s an absolute must. Come, let’s embark on this journey together!

Understanding the Product

Before the hunt begins, I believe in first understanding the prey. I carefully examine what the product offers, its highlighted features, and its promises. From here, I meticulously list down all critical services it provides. This also involves understanding its infrastructure like the hosts it uses, the APIs it’s reliant on, and any third-party calls that might be made.

Reconnaissance – Scanning the Battlefield

Once the basics are clear, I roll up my sleeves for some aggressive recon. Here’s a glimpse:

  • Authentication Flow: I ensure that mechanisms like JWT token generation and expiration function as they should. I often try different use cases just to see how the system reacts.
  • Attack Surfaces: Everything from user inputs, directory structures, Assets Discovery,port & service scanning to subdomains gets scrutinized.
  • Digital Footprints: The internet often has traces of our digital presence. I search for exposed assets, which could give me an edge.
  • Git Dives: A little dumpster diving into the company’s public repositories might reveal some hidden gems (or secrets).
  • JS Analysis: I believe in the power of JS file analysis – scraping endpoints often offers valuable insight.

Going Manual – The Art of the Attack

While automated scans are running, I shift to manual mode, turning my attention to some core components:

  1. Know Your Customer (KYC): Practically every fintech app has a KYC process. Messing up here can be disastrous. I probe by tweaking parameter values and closely watch the responses.
  2. Authorization: Whether it’s OAuth or any other identity provider, I’m on the hunt for vulnerabilities. Historical issues, CVEs, and, most importantly, configurations.
  3. Insecure Direct Object References (IDORs): Unique identifiers are the usual suspects. Can I manipulate data for another user? That’s the key question here.
  4. Transactions: This is the heart of any fintech. I aim to understand and then exploit any vulnerability in transaction flows.Mostly Business logic flaws.
  5. Activation Processes: Be it for a card or a loan, can I trick the system?
  6. Code-based Flows: If there’s a QR or any kind of code generation, there’s an avenue for probing.
  7. Account Takeovers: Because who doesn’t want to be the king of the castle?
  8. Interest Computations: A crucial element in fintech, I check if the interest calculations or their sources can be tampered with.

There are more test cases and other important components to look for but these are most crucial attack surface in most apps.

Once I have my findings, I focus on gauging their business impacts. An issue isn’t just a technical glitch; it can have ramifications that could shake a business to its core.

Pentesting isn’t just a job for me; it’s an art and a responsibility. In a world that’s rapidly digitizing its assets, ensuring the security of financial technologies is not just a requirement, but a mandate.

Until next time, stay secure and keep exploring