𝗕𝘂𝘀𝗶𝗻𝗲𝘀𝘀 𝗟𝗼𝗴𝗶𝗰 𝗔𝘁𝘁𝗮𝗰𝗸𝘀 𝗘𝘅𝗽𝗹𝗮𝗶𝗻𝗲𝗱

Attackers do not always break your code to steal money.

Many developers spend months securing APIs and encryption. They focus on stopping SQL injection or XSS. Then an attacker steals funds without breaking a single security control.

This is a business logic attack.

The application works exactly as designed. The attacker simply uses your own rules against you.

Think of a bank vault. Most security tests check if the door is strong. Business logic testing asks a different question. What if someone convinces the guard to open the door for them?

The vault works. The process fails.

Here are three ways attackers abuse banking logic:

  1. Bypassing Waiting Periods Banks often require a 24-hour wait after adding a new recipient. This prevents quick theft. An attacker might find an API endpoint that skips this check. They bypass the UI restriction and move money instantly.

  2. Breaking Transaction Limits A bank might set a daily limit of 50,000. If the code only checks each transaction individually, an attacker can send five transfers of 49,000. Each transaction looks valid. The total sum exceeds the limit, but the system misses it.

  3. Reward Abuse Many apps give cashback for bill payments. An attacker might pay a bill and then immediately cancel it. If the system does not revoke the reward, the attacker creates a loop to collect endless cashback.

Why do automated scanners miss this?

Scanners look for technical flaws like malware or injection. A scanner sees a successful transfer and returns a status of 200 OK. It thinks everything is fine.

A human tester asks: Should this transfer have happened at all?

To find these flaws, stop asking if a feature can be hacked. Start asking if a feature can be abused.

Check these areas:

  • Can users skip verification steps?
  • Can users change ownership of an ID?
  • Can waiting periods be bypassed via API?
  • Are limits enforced on the total amount or just per click?
  • Can rewards be triggered multiple times?

Elite security teams do not just create use cases. They create abuse cases.

Instead of testing "User transfers money," test "Attacker attempts 500 small transfers to bypass limits."

The second question finds the real risk.

Source: https://dev.to/arashad_dodhiya_0e4bdba5a/business-logic-attacks-explained-using-a-banking-app-27hj