Anti-Sandwich Toolkit

Built by the team behind the Solana MEV dashboard Sandwiched.me

A minimal proof-of-concept demonstrating how Solana applications can react at runtime when their transaction is routed to a malicious validator.

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Overview

This toolkit provides a single lightweight primitive that enables applications to take defensive action when detected on a malicious validator. Your application can either:

1. Abort – Emit a custom error so nothing executes on-chain
2. Adjust slippage on the fly – Lower tolerance for the transaction when it lands on a malicious validator

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Use Cases

Call Site	When You'd Use It
Raw Instruction	You want to revert entirely when the transaction ends up landing on a malicious validator
Jupiter Wrapper	The SDK wraps a normal Jupiter swap and tweaks slippage_bps when running on a malicious validator
CPI	Another on-chain program can perform the check and adjust behavior at runtime

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Quick Start

Building and Testing

Build the On-Chain Program

$ cargo build-sbf --manifest-path program/Cargo.toml

Run Unit Tests

$ cargo test --manifest-path common/Cargo.toml

Run the Examples

Abort Example:

$ cargo run -p abort-example           

tx M5QkYp6 succeeded, as expected. CU=246
tx 4M3kUHi aborted (errno=100), as expected. CU=256

Adjust Slippage Example:

$ cargo run -p adjust-slippage-example 

=== Transaction Result ===
Transaction succeeded. 20 SOL -> 3258.630597 USDC
CUs: 553058
--> Program log: adjusting slippage? = no

=== Transaction Result ===
Simulated landing on nefarious validator. Slippage was adjusted 6% -> 2% at execution-time
Transaction err was: Error processing Instruction 6: custom program error: 0x1771
CUs: 544370
--> Program log: adjusting slippage? = yes
--> Program log: adjusting slippage to 200 bps
(error was expected since in this sim the validator is malicious)

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Repository Structure

Common Functionality (common/)

common::NefariousWindow

Field	Size	Purpose
window_start	u64	First slot in the 192-slot look-ahead window
nefarious	[u8; 6]	48-bit bitmap → 1 bit per 4-slot leader chunk

Why 192 slots? A Solana transaction stays valid for approximately 151 slots. The 192-slot window provides full coverage plus additional slack for client-side caching.

On-Chain Program (program/)

Built using Pinocchio

Discriminator	Entry Point	Action
1	process_abort_if_nefarious	Returns custom error 100 if any targeted slot's leader is nefarious
2	process_adjust_slippage_and_forward	Patches the incoming Jupiter instruction with a fallback slippage and then CPI-forwards it
3	process_report_if_nefarious	Your program calls this via CPI to determine if the current validator is flagged

Basic dispatch handled in process_instruction.

SDK Quick-Start (sdk/)

use anti_sandwich_sdk::{
    abort_if_nefarious,
    adjust_slippage_at_runtime,
};

fn build_tx() -> Transaction {
    // Abort entirely if the TX might land on a flagged leader
    let ix = abort_if_nefarious(
        &nefarious_slots,  // Vec<u64> of upcoming, malicious leaders
    )?;

    // Or, swap with tighter slippage
    let jupiter_ix = /* build via Jupiter API */;
    let ix = adjust_slippage_at_runtime(
        &nefarious_slots,
        /* slippage_if_nefarious = */ 50,  // in basis points
        jupiter_ix,
    )?;
}

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Frequently Asked Questions

Is this production-ready?
No, this is experimental software.

Is it audited?
No, this code has not been audited.

Does this "solve" MEV?
No. This toolkit addresses one specific case of MEV (malicious validators who will sandwich your swap transaction) and provides a mechanism to adjust your program's behavior at runtime, depending on which validator it lands on.

Any disclaimers?
Yes. This code is being provided as is. No guarantee, representation or warranty is being made, express or implied, as to the safety or correctness of the code. It has not been audited and as such there can be no assurance it will work as intended, and users may experience delays, failures, errors, omissions or loss of transmitted information. Nothing in this repository should be construed as investment advice or legal advice for any particular facts or circumstances and is not meant to replace competent counsel. It is strongly advised for you to contact a reputable attorney in your jurisdiction for any questions or concerns with respect thereto. The author is not liable for any use of the foregoing, and users should proceed with caution and use at their own risk.

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License

This project uses multiple licenses:

• sdk and examples crates: MIT and Apache-2.0 licensed
• common and program crates: GPL-licensed