Digitizing cocoa. The receipt is the currency.

Akande Simpa Lead Security Engineer & Cofounder, Simpa Labs CEH (Certified Ethical Hacker)

The flow of agritech supply chain finance

In agricultural hubs across Ondo, Kaduna, Kano, and Taraba, physical commodities represent instant liquidity. Smallholder farmers and commodity brokers transport cocoa bags or maize bags to verified warehouses managed by platforms such as AFEX or Babban Gona.

The platform issues a digital Warehouse Receipt (WHR) representing ownership of the commodity. This digital token contains metadata: the grade, the weight, the moisture content, and the location. The farmer uses the WHR to secure short-term credit from digital lenders or trading platforms. Lenders disburse funds based on the digital ledger, assuming the physical cocoa or maize is locked in a verified vault.

Exploit 1: Double-pledging collateral

When a borrower pledges a WHR for a loan, the platform's API must lock the receipt status. If the locking logic is slow or lacks database row-level isolation, an attacker can exploit a race condition.

By submitting loan requests to two different digital lenders simultaneously using the same WHR ID, the attacker can secure two loans against one physical asset.

Consider the vulnerable API code below:

// Vulnerable Express controller using Prisma
app.post("/api/loans/apply", async (req, res) => {
  const { receiptId, lenderId, loanAmount } = req.body;

  // Step 1: Check receipt availability
  const receipt = await prisma.warehouseReceipt.findUnique({
    where: { id: receiptId },
  });

  if (!receipt || receipt.status !== "UNPLEDGED") {
    return res.status(400).json({ error: "Receipt is already pledged" });
  }

  // Step 2: Approve the loan
  const loan = await prisma.loan.create({
    data: {
      receiptId,
      lenderId,
      amount: loanAmount,
      status: "APPROVED",
    },
  });

  // Step 3: Mark receipt as pledged
  await prisma.warehouseReceipt.update({
    where: { id: receiptId },
    data: { status: "PLEDGED" },
  });

  return res.json({ loan });
});

If the attacker fires two concurrent POST requests, both requests read the database state before either request completes the update. The database records two active loans against the same WHR. The attacker walks away with double the loan value.

Exploit 2: Receipt quantity manipulation (BOLA/BOPLA)

The API endpoint to update receipt quantities after warehouse intake typically looks like: PUT /api/receipts/{receiptId}.

If the endpoint checks that the user is a warehouse worker but fails to check if they are authorized for that specific warehouse location, a worker can inflate receipt quantities. This is a Broken Object Level Authorization (BOLA) and Broken Object Property Level Authorization (BOPLA) flaw.

The HTTP request below demonstrates the attack:

PUT /api/receipts/whr-992-cocoa-2026 HTTP/1.1
Host: api.agritech.local
Authorization: Bearer worker_jwt_token_here
Content-Type: application/json

{
  "quantity": 100.0,
  "warehouseId": "WH-KADUNA-04"
}

If the worker is assigned to an Ondo warehouse but the endpoint allows them to edit a Kaduna receipt, they can modify arbitrary receipt quantities. A colluding worker can inflate a relative's receipt from 10 metric tons to 100 metric tons, enabling a massive fraudulent loan.

Exploit 3: Price oracle manipulation

Supply chain finance platforms calculate loan-to-value (LTV) ratios based on live market pricing APIs. If the price query endpoint has no validation or rate limits, attackers can feed spoofed market data payloads to inflate the collateral value of their receipts.

For example, if the platform queries an external API for the spot price of cocoa without signature verification, a middleman can spoof the responses.

Alternatively, if the API allows client-side input to override the market price during the LTV calculation request, the frontend parameters can be manipulated:

POST /api/loans/calculate-ltv HTTP/1.1
Host: api.agritech.local
Content-Type: application/json

{
  "receiptId": "whr-992-cocoa-2026",
  "marketPriceOverride": 8500000.0
}

Without server-side validation against a secure price oracle, the backend calculates the LTV based on the fake price, issuing an un-collateralized loan.

The business impact

When the physical warehouse inventory does not match the digital ledger, the platform faces massive un-collateralized loan defaults.

In Nigeria, the Securities and Exchange Commission (SEC) regulates commodities exchanges. Regulatory audits can lead to license suspension and heavy fines. Furthermore, under the Nigeria Data Protection Act (NDPA), exposed BVNs and farmer data result in NDPC penalties. Finally, institutional investors and lenders withdraw funding once collateral validation breaks down.

The fix

Securing supply chain finance APIs requires database-level controls, cryptographic hardware signatures, localized scoping rules, and strict session verification.

To resolve the double-pledging race condition, use database transactions with pessimistic locking. This prevents concurrent reads from modifying the same receipt.

// Secure implementation using raw SQL row-level locking
const result = await prisma.$transaction(async (tx) => {
  // Use SELECT ... FOR UPDATE to lock the row in PostgreSQL
  const [receipt] = await tx.$queryRaw<any[]>`
    SELECT id, status FROM "WarehouseReceipt" 
    WHERE id = ${receiptId} FOR UPDATE
  `;

  if (!receipt || receipt.status !== "UNPLEDGED") {
    throw new Error("Receipt is already pledged or does not exist");
  }

  // Update status atomically
  const updatedReceipt = await tx.warehouseReceipt.update({
    where: { id: receiptId },
    data: { status: "PLEDGED" },
  });

  const loan = await tx.loan.create({
    data: {
      receiptId,
      lenderId,
      amount: loanAmount,
      status: "APPROVED",
    },
  });

  return { loan, updatedReceipt };
});

Additionally, apply these critical architectural changes:

• IoT Scale Authentication: Implement mTLS for all warehouse weighing scales. Scale readings must be signed at the hardware level using a private key and validated on the backend.
• Strict Location Scoping: Implement strict role-based access control (RBAC) on receipt modification endpoints. Verify that the worker's assigned location matches the receipt location.
• Multi-Source Price Oracles: Use multiple price feeds with anomaly filters. Disregard spot price updates that deviate significantly from the moving average.

Automated scanners check for SQL injection. They do not verify whether your digital ledger matches physical supply chain gates or IoT scale integrations.

Related reading

Blog: Webhook Security for Payment Platforms · Securing KYC and BVN Data

Services: API security testing · Secure architecture review