Skip to main content

Header

Fraud Detection Framework

TL;DR / Quick Answer: BDX.market protects digital trades using a multi-layered Fraud Detection Framework featuring device fingerprinting, real-time risk scoring, manual bKash/Nagad TrxID duplicate checks, off-platform chat interception, and a mandatory 7-day buyer protection holding period. Orders scoring high behavioral risk trigger automatic step-up verification, payout holds, or manual compliance reviews.

Digital gaming marketplaces operating in C2C environments face distinct security challenges: account recovery fraud, chargeback exploitation, fraudulent manual payment proofs, compromised seller credentials, and automated bot networks. BDX.market implements a multi-layered Fraud Detection Framework that combines real-time transaction monitoring, behavioral scoring, network intelligence, and ledger auditing.

This document describes the architectural safeguards, detection heuristics, payment verification layers, and automated containment actions enforced across BDX.market to maintain transaction integrity.

Architectural Security Layers​

The Fraud Detection Engine operates across four defense perimeters: Network/Device level, User Behavioral level, Order/Transaction level, and Financial Ledger level.

┌─────────────────────────────────────────────────────────┐
│ Layer 1: Network & Device Perimeter                     │
│ - IP Reputation / VPN / Proxy / TOR Detection           │
│ - Fingerprinting (Browser, Canvas, User-Agent)          │
└────────────────────────────┬────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────┐
│ Layer 2: Account Behavior & Velocity Engine             │
│ - Rapid Account Switching / Device Reuse                │
│ - Velocity Anomaly (Unusual Order Frequency)            │
└────────────────────────────┬────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────┐
│ Layer 3: Order & Payment Proof Verification             │
│ - Manual bKash/Nagad TrxID Duplicate Inspection         │
│ - Chat Link & External Contact Extraction               │
└────────────────────────────┬────────────────────────────┘
                             │
                             ▼
┌─────────────────────────────────────────────────────────┐
│ Layer 4: Ledger Audit & Payout Freeze                   │
│ - Automated Double-Spend Checks                         │
│ - Mandatory 7-Day Protection Holding Vault               │
└─────────────────────────────────────────────────────────┘

Threat Vectors & Countermeasures​

BDX monitors specific fraudulent patterns commonly targeted at digital product and gaming marketplaces in Bangladesh:

1. Fake Payment Proofs (bKash / Nagad TrxID Fraud)​

  • Threat: Buyers submitting fake transaction IDs (TrxIDs) or manipulated SMS screenshots during manual payment checkout to trick sellers into instant delivery.
  • Countermeasure: Manual payment submissions require unique TrxID validation against the BdxOrder database. If a TrxID matches an existing transaction, the order is instantly locked with state PAYMENT_DUPLICATE_FLAG. Orders remain held in PAYMENT_PENDING until financial administrators verify gateway logs or automated MFS callback webhooks.

2. Off-Platform Payment Evasion & Escrow Bypass​

  • Threat: Fraudulent sellers enticing buyers to leave BDX protection, requesting direct bKash transfers with promises of extra discounts, followed by non-delivery.
  • Countermeasure: Real-time message scanning (App\Support\BdxMessageSafety) automatically intercepts payment-related keywords (send money, cash out, personal number) and blocks message delivery. Sellers attempting repeat bypass incur automatic account freezing.

3. Account Reclamation Fraud (Gaming Accounts / Steam / Origin)​

  • Threat: Fraudulent sellers selling a high-value gaming account (e.g., Valorant, Free Fire, Clash of Clans), transferring access to the buyer, receiving payout, and then using recovery emails/first-purchase receipts to reclaim the account 10 days later.
  • Countermeasure: Sellers of gaming accounts are subjected to mandatory Tier 1/2 KYC verification. Account listings require recorded proof of original email ownership release. Furthermore, high-value account payouts incur extended holding windows (up to 14 days) to ensure buyer ownership stability.

4. Multi-Account Evasion (Sybil Attacks)​

  • Threat: Banned sellers creating multiple alternative accounts using disposable email services and VPNs to continue fraudulent activity.
  • Countermeasure: Multi-attribute fingerprinting links accounts sharing identical device canvas hashes, browser signatures, IP subnets, or identical bKash/Nagad payout withdrawal numbers.

Behavioral Risk Scoring Matrix​

Every order initiated on BDX.market receives a dynamic risk score computed at checkout initiation (/checkout/{offer}). The score determines whether an order proceeds directly, requires step-up authentication (2FA), or is routed for manual compliance review.

namespace App\Services\Risk;

class OrderRiskEvaluator
{
    public function calculateRisk(User $buyer, BdxOffer $offer, array $context): int
    {
        $score = 0;

        // Condition 1: Account Age < 24 Hours
        if ($buyer->created_at->diffInHours(now()) < 24) {
            $score += 25;
        }

        // Condition 2: High Value First Order (> 10,000 BDT)
        if ($buyer->orders()->count() === 0 && $offer->price_bdt > 10000) {
            $score += 35;
        }

        // Condition 3: Proxy / VPN Usage Detected
        if ($context['is_proxy'] ?? false) {
            $score += 20;
        }

        // Condition 4: Rapid Order Velocity (> 5 orders in 10 mins)
        if ($buyer->recentOrderCount(10) > 5) {
            $score += 30;
        }

        return $score;
    }
}

Risk Level Actions​

Computed Risk ScoreRisk ClassificationAutomated Enforcement Action
0 – 19Low RiskOrder proceeds normally to payment execution.
20 – 49Medium RiskRequires 2FA confirmation; manual payment proof undergoes double-checking.
50 – 79High RiskOrder flagged for manual review; payout protection window extended by +3 days.
80+Critical RiskOrder blocked instantly; user account placed under security hold pending verification.

Payout Hold & Balance Protection Protocols​

The ultimate containment barrier against marketplace fraud is financial isolation. BDX ensures funds are locked in platform escrow until trade legitimacy is proven beyond doubt.

  1. 7-Day Buyer Protection Holding Window: When a buyer confirms order delivery or when an order auto-completes after 7 days, funds move from buyer escrow into the seller's pending_balance ledger (BdxWallet). Funds cannot be withdrawn until cleared.
  2. Automated Payout Lock on Dispute: If a buyer opens a dispute (BdxDispute) within the protection window, the associated order funds are immediately locked. The seller cannot request withdrawals against disputed amounts while the dispute remains active.
  3. Emergency Wallet Freeze: Financial administrators possess the capability via the Filament Admin Panel (SellerProfiles resource) to execute a one-click Freeze Payouts action. A frozen wallet prevents all pending withdrawal requests (SellerPayoutRequest) from processing until compliance clears the investigation.

Security Audit Logging & Evidence Preservation​

All security events, risk flags, wallet updates, and moderation actions produce structured audit trails.

  • Immutable Audit Logs: Filament audit tables (audit_logs) capture timestamps, IP addresses, operator IDs, and before/after state snapshots for every risk override, balance adjustment, or account suspension.
  • Evidence Package Export: In the event of legal escalations or severe fraud inquiries, BDX generates an immutable zip package containing encrypted chat transcripts, payment receipt snapshots, IP logs, and system event markers for law enforcement review in accordance with Bangladesh legal standards.
Last updated on