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Know Your Agent needs a memory

Visa, Mastercard and Ant are building agent identity. The attacks that drained agent wallets this year were about something else: what the agent did.

Agentic Finance Graph · Published 2026-09-25 · Written 24 Sep 2026 · ~1,600 words

Direct answer Identity checks tell you who an agent is. The agent-wallet losses of 2026 were about what agents did. In the documented May 2026 drain, the agent was exactly who it said it was; it paid an attacker because of a hidden instruction. Catching that needs a history of each agent's behaviour, which is the half of Know Your Agent nobody publishes yet.

On 10 September, Ant International, Visa and Mastercard announced they would work together on a "Know Your Agent" framework: a shared way to link an AI agent to a real entity, check whether it's authorised, and monitor what it does, so an agent verified with one payment provider doesn't have to start over with the next.

That's a good idea, and it's overdue. But look at how agent wallets actually lost money this year, and a gap shows up. Almost all of the work so far is about who an agent is. The attacks are about what it does.

The agent was exactly who it said it was

In May 2026, according to Ledger, attackers drained roughly $175,000 from a Grok-linked Bankrbot wallet. There was no smart-contract bug, no stolen private key and no compromised bridge. There was a hidden instruction inside ordinary content. The agent read it, treated it as a legitimate order, and the transfer settled in seconds. The Bankr team later recovered the funds, Ledger notes, but nothing about the agent’s identity would have stopped the transfer.

In July, Zscaler described two campaigns built on the same idea. One hid payment instructions inside a fake API documentation site, targeting agents that search for software packages. The other impersonated DeBank to win an agent's trust. Zscaler then tested 26 language models with a browsing, paying agent of its own. Four of them followed the hidden instructions all the way to a payment.

In both cases, identity was never the problem. Nobody forged an agent or stole a wallet. The agent's registration would have checked out, its wallet was its own, its operator was real. What went wrong was behaviour: the agent paid someone it had no reason to pay. In the Bankrbot case, it sent far more than it normally would, to an address it had never dealt with.

Identity answers "who is this agent?" The question that catches a drain is "has this agent ever done this before?" You can only answer the second one if someone has been keeping a history.

What a drain looks like on-chain

We already follow every payment from every wallet bound to a registered agent on Base, so we can describe the shape precisely. On 24 September we switched on a detector for it. It flags a payment that is:

  • at least five times the agent's previous largest payment,
  • at least $250,
  • sent to an address the agent has never paid before,
  • after at least three earlier payments, so there's a history to compare against.

In its first 30-day window it found exactly one case: an agent that had made 48 payments of five cents or less, then sent $250 to a new address.

We don't know whether that was a theft. A legitimate one-off purchase leaves exactly the same shape, and that's the point. The detector reports a shape, with the evidence, for a human to read. It never declares a verdict, and it never names the agent publicly. A monitoring system that cries theft every time someone buys something would be switched off within a week. The detection log →

Ten ways agent money goes wrong

The drain is one pattern. Writing down everything we can see from our position, we count ten, and we already watch for several of them:

The threat model we work from, and what is watched today (24 Sep 2026).
#What goes wrongStatus
1Prompt-injected drains: hidden instructions make the agent pay an attackerDetected (drain pattern)
2Retry storms: a broken loop pays the same counterparty over and over, burning feesDetected
3Identity hijack: the registration changes owner, so the bound wallet now belongs to someone else's agentDetected
4Delegated control: a wallet hands control to unknown code under EIP-7702Built; waiting on a curated allowlist, because unknown doesn't mean malicious
5Registration spam: thousands of identities minted in burstsDetected: 280 bursts, 27,363 registrations
6Reputation farming: ten raters wrote 51.7% of all on-chain agent reputationMeasured; detector to build
7Look-alike sellers: an agent pays a service imitating a real oneTo build
8Allowance drains: an agent approves a token spender it shouldn'tTo build
9Dead or hijacked endpoints: a service stops answering, or answers for someone elsePartly detected
10Metric poisoning: wash payments and self-dealing to fake traction, aimed at every leaderboard including oursWhy only 15.6% of agent-wallet outflow counts as spending

We keep two words apart on purpose. A detection is a shape with evidence that someone should read. An incident is a detection that is also a harm, and recent. On 24 September there were 303 detections logged and zero live incidents. Zero is the normal answer.

The layers fit together

None of this replaces anything else. The sensible setup for anyone running an agent with money looks like three layers:

  • Prevention at the key: spending limits and signing policies, the approach hardware wallet makers such as Ledger are building for agents. Valet keys vs trunk keys →
  • Identity at the network: Know Your Agent, as Visa, Mastercard and Ant are designing it.
  • Detection from behaviour: a history of what each agent normally does, and an alert when it does something else.

The third layer is the one nobody publishes in the open. Payment networks will monitor their own rails, and exchanges will watch their own custody. But an agent that pays over x402 on Base, keeps funds with one custodian and is rated in another registry needs a view across all of them. No single platform has a reason to build that view, or to publish its own bad numbers.

What we're building

This is where Agentic Finance Graph is going next. The Desk lets anyone bind the agents they run and get told, in real time, when one of them acts out of character. Allow-lists stop legitimate purchases from looking like drains. Every alert comes with what we saw and what to check, and we never act on the wallet ourselves. We watch; we never sign. Register for the Desk →

Further out, two things follow naturally. One is a public incident registry: confirmed agent-money incidents with stable IDs, the on-chain evidence and a plain write-up, something like CVEs for agent finance. The other is an agent behaviour file: a history that Know Your Agent providers and marketplaces can read before they let an agent move money. Identity from the networks, behaviour from the record.

A note on our own responsibility

Watching agents means holding something sensitive. Once people bind their agents to an account, we hold a map of who runs what, which is exactly the kind of data an attacker would want. So the rules are simple and non-negotiable. We never hold keys, move funds or sit in the payment path, today or later. When the Desk opens, watch-lists will be encrypted per user and never appear in any public document, and any figure built from Desk data will only be published when enough users stand behind it that no one can be singled out. Everything we publish is already signed, so a tampered copy can be spotted.

Know Your Agent is a good start. But an agent's identity only tells you who to blame after the money is gone. Its history can tell you before.

Sources: Ledger Academy, "Best practices when using AI agents in crypto" (15 Jul 2026); SecurityWeek reporting Zscaler research (6 Jul 2026); crypto.news and Forkast on the Know-Your-Agent framework (Sep 2026). Our figures: Agentic Finance Graph, Base mainnet, 24 Sep 2026, /api/detections.

Questions people actually ask

How are AI agent wallets being drained?
Mostly through prompt injection: hidden instructions in content the agent reads make it pay an attacker. In May 2026 a Grok-linked Bankrbot wallet sent about $175,000 to an attacker this way, according to Ledger; no contract bug or stolen key was involved, and the funds were later recovered.
What is Know Your Agent (KYA)?
A framework Ant International, Visa and Mastercard announced on 10 Sep 2026 to link AI agents to real entities, check their authorisation and monitor them across payment providers. It establishes who an agent is; it does not yet provide a public history of what agents do.
What does a drain look like on-chain?
A payment far larger than the agent's usual size, to an address it has never paid. Our detector flags payments at least five times the agent's previous largest, at least $250, to a new counterparty, after at least three earlier payments. A legitimate one-off purchase looks the same, so it reports a shape for a human to read, never a verdict.