> For the complete documentation index, see [llms.txt](https://funarchy.gitbook.io/funarchy/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://funarchy.gitbook.io/funarchy/security-for-prediction-market/trading-mechanism/amm-risks/slippage-and-sandwich-attacks.md).

# Slippage & Sandwich Attacks

#### Description

In AMM-based prediction markets, the buy and sell functions must receive parameters such as the minimum amount received (`minAmountOut`) or maximum price allowed (`maxPriceLimit`) from users to limit slippage.

AMMs have the advantage of enabling trading without liquidity gaps, but if slippage verification is not properly performed, users may receive tokens at a rate significantly less favorable than expected, and attackers may profit from the difference.

#### Attack Scenario

**Scenario - Absence of Slippage parameters**

```javascript
// Scenario - Slippage Parameter nonexist code

function vulScenario(address recipent) external payable {
    ...
    // No Slippage Check!!
}
```

{% stepper %}
{% step %}
The attacker captures the victim's transactions from the mempool.
{% endstep %}

{% step %}
The attacker submits a transaction with a higher gas fee than the victim.
{% endstep %}

{% step %}
The victim receives much less tokens (or at a much higher price) than expected.
{% endstep %}

{% step %}
The attacker immediately enters into an opposite position to lock in the profit.
{% endstep %}
{% endstepper %}

#### Mitigation

* **Slippage parameter required**
  * When calling the `buy()` or `sell()` function, it must be designed to include slippage-related parameters such as the minimum amount received (`minAmountOut`) and the maximum allowed price (`maxPriceLimit`).


---

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