Essay

Why fraud models should only propose. By Amir Shachar.

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Riskernel

Payments, scams and platform abuse

Free credits cost you real compute. Do you know who is spending them?

On most AI products every free request is GPU time you pay for. One operator with many accounts, a resold key or a metering bug looks like healthy growth on the signup chart and shows up only as a gross margin that keeps slipping.

Built for Usage-priced AI and API platforms with free tiers or trial credits; Head of Growth, Head of Trust and Safety, CTO, VP Engineering

The problem in numbers

What the public record shows

Every figure links to the page it came from, with its date.

7.4%

of customer sign-ups at AI companies implicated in suspected multi-account abuse, based on a Stripe analysis

stripe.com, 2026-03-10

10x

more attempted abuse at AI startups with free trials, self-serve sign-ups and direct API access than at enterprise AI products, per Stripe

stripe.com, 2026-03-10

46,000

US dollars or more per day: what one leaked cloud key could cost its owner in AI model usage, in Sysdig's 2024 worst-case estimate

sysdig.com, 2024-05-06

600,000

US dollars: the approximate value of AI model credits attackers burned through with one stolen API key at METR, a research nonprofit, in March 2026

metr.org, 2026-08-31

What you get

The deliverables

You get a fixed-scope forensic audit of your signup, payment and usage logs that sizes the loss and hands over blocking rules.

Accounts grouped by operator

Signups joined across device, network, normalized email and phone, and payment method, so a few hundred 'users' that are really a handful of people show up as such.

A loss figure finance can check

The compute cost sized separately for free-credit farming, multi-accounting, key resale and metering gaps, with the queries behind each number.

Blocking rules ready to ship

A short set of rules your engineers can put into production, each with the share of the loss it would have stopped and the number of real users it would have touched.

A written readout

A plain report for growth, finance and engineering, and a call to walk through it.

How it runs

Fixed scope; the length is agreed on a short call and set by the log period you share, start to finish

Fixed scope; the length is agreed on a short call and set by the log period you share

  1. Scope and data
  2. Group and size
  3. Rules and readout
Step 1

Scope and data

You share exports of signup, payment and usage logs for an agreed period. Nothing is installed in production.

Step 2

Group and size

Accounts are grouped by the operator behind them and the loss is sized across the four leak types.

Step 3

Rules and readout

Blocking rules are tested on the same data, then handed over with the report and a readout call.

Consent. Your written consent covers read-only access to the log exports you choose to share, under an agreed data-handling note. No live users are contacted or affected.

Method

How the answer is produced

Look at the person, not the account

Farming only becomes visible when accounts are grouped by the operator behind them, so the audit joins signup, payment and usage data at that level.

Your existing data only

It is forensic work on logs you already have, not a new product to integrate.

Every rule is measured both ways

Each proposed rule is measured on how much abuse it stops and how many genuine users it would have blocked.

Amir Shachar
Amir ShacharFounder, Riskernel

Why Amir

Designed and led by someone who has built fraud models in production

The patents closest to this problem:

Amir is a named inventor on US 12,476,990 B2 (Method and system for early detection of malicious behavior based using self-supervised learning, filed at Skyhawk Security; granted).

Covers spotting malicious behavior in cloud activity early, without labeled examples. It is related to the audit's problem, because newly farmed accounts have no fraud history yet.

View on Google Patents

Amir is a named inventor on US 12,541,721 B2 (Method for extreme class imbalance within fraud detection, filed at NICE Actimize; granted).

Covers building a detector when the bad class is a tiny fraction of the data, which is the case for abusive operators among signups.

View on Google Patents

These patents were filed at the companies named. They show the problems Amir has worked on; they are not Riskernel products.

Is this you

You probably need this if

  • Compute cost on the free tier is rising faster than paid revenue.
  • You give signup credit or a free trial and have never counted how many accounts share one device or network.
  • You have seen sudden usage spikes from new accounts that burn their full credit through the API and then go quiet.
  • A customer has reported a leaked or misused API key.
  • Nobody has compared what your servers recorded as used with what billing charged for the same date.

Questions

Before you reach out

Do we need to install anything?

No. The audit works on exports of logs you already keep. Nothing changes in production unless your team ships the rules afterwards.

What data do you need?

Signup records, payment or card checks, and usage or billing logs for an agreed period. Scope is agreed on a short call.

Is this only about fraud?

No. Metering gaps, usage served but never billed, are usually bugs rather than attacks. The audit sizes them alongside the abuse.

Why does this matter when raising money?

Stripe's analysis puts 7.4% of sign-ups at AI companies in suspected multi-account abuse. A measured figure for your own product, with the rules that contain it, is a stronger answer to questions about user and revenue quality than an estimate.