Summary: Sandwich attacks quietly turn user swaps into “invisible fees,” inflating slippage, stalling carts at checkout, and eroding LTV. This playbook shows how DeFi teams can harden execution with order-flow auctions, private routing, and Uniswap v4 hooks—delivering measurable price improvement, lower failure costs, and Gas optimization.

Title: MEV Protection: How to Shield Your Users from Sandwich Attacks

Target audience: DeFi product and protocol teams (keywords: Gas optimization, slippage control, TVL retention, order-flow auctions, Uniswap v4 hooks)

Pain — your specific headache right now

• You ship a pricing update, but users still see “execution price worse than quoted” on peak volatility. Post-trade analysis shows sequential swaps in the same pool, abnormal tick jumps, and a burst of reverted transactions right before inclusion. That pattern is textbook sandwich flow.
• 90%+ of Ethereum blocks are sourced via MEV-Boost, with three builders historically producing ~80% of blocks across observed periods—so attackers don’t need to watch every mempool; they only need to anticipate builder behavior. That concentration exacerbates predictability of ordering and makes naive “just raise slippage” guidance self-defeating. (blog.rated.network)
• “Private routing” alone isn’t a panacea. A 2025 study documented thousands of sandwich events even on private paths, plus measurable user churn after first-time attacks—which shows that simply flipping an RPC does not eliminate the risk surface. (arxiv.org)

Agitation — the business risk if you delay

• Every 10 bps of adverse execution on a $50M monthly swap flow is $50,000 of silent leakage—before you count failed swap gas and support churn. OFA research shows auction-enhanced routing can deliver 4–5 bps of price improvement; without it, you leave that spread to searchers and builders. (arxiv.org)
• The longer you rely on public mempool routing, the higher your abandon rate: empirical work links sandwich exposure to user migration or churn; meanwhile, press continues to highlight monthly Ethereum sandwich losses in the millions—this is visible to your users and your competitors. (arxiv.org)
• Near-term protocol upgrades won’t bail you out. Enshrined PBS (ePBS) is advancing toward mainnet but is not a switch you can flip today; planning must assume the current MEV-Boost ecosystem for the next product cycles. Teams that are “ePBS-ready” will still need OFAs, private routing policies, and hook-level mitigations to capture price improvement when ePBS arrives. (blog.ethereum.org)

Solution — 7Block Labs’ layered MEV defense for DeFi We deploy a defense-in-depth stack that combines protected order flow, intent-based execution, and AMM-level controls—engineered for measurable ROI, not just “security theater.”

Layer 0: Baseline telemetry and ROI model

• Instrument “effective price improvement” (EPI): compare on-chain execution vs pre-trade quote with venue attribution (AMM vs intent auction) and capture rebates separately. Use OFA benchmarks (bp uplift) to set SLOs per pair and chain. (arxiv.org)
• Track sandwich fingerprints: sequential pool interactions, deltaTick spikes, priority fee patterns, and backrun traces. Maintain a builder/relay watchlist using Rated/EF data and Flashbots SSE feeds. (blog.rated.network)

Layer 1: Protected order flow by default (no code freeze required)

• Flashbots Protect + MEV-Share: Route swaps to a MEV-Share Node with selective “hint” disclosure; only pool/pair addresses and tx hash are revealed by default. 90% of backrun value is refunded by design; customize privacy for high-value orders. (docs.flashbots.net)
• MEV Blocker RPC profiles: For consumer traffic, default to /fast; for “do not reveal” flows (launches, whale redemptions), toggle /fullprivacy; when you want both rebates and revert protection, use /noreverts. Builders covered include Flashbots, Titan, Builder0x69, bloXroute, and Beaver Build. Note the explicit 0.1% reorg edge case—private routing is not a 100% guarantee. (mevblocker.io)
• Practical integration detail: Protect RPC deprecations (Nov 17, 2025) require signing eth_sendPrivateTransaction requests via X-Flashbots-Signature; unify on relay.flashbots.net to reduce operational drift. Rate-limit and auctionTimeout tuning are available. (collective.flashbots.net)

Example (JS/ethers): Force private settlement for a high-value swap

import { Wallet, providers } from 'ethers';
import { FlashbotsBundleProvider, FlashbotsTransactionResolution } from '@flashbots/ethers-provider-bundle';

const auth = Wallet.createRandom();
const provider = new providers.JsonRpcProvider(process.env.L1_RPC);
const fb = await FlashbotsBundleProvider.create(provider, auth);

const tx = {
  to: process.env.SWAP_ROUTER,
  data: process.env.CALldata,      // pre-simulated swap call
  maxFeePerGas: '0x' + (30n * 1_000_000_000n).toString(16),
  maxPriorityFeePerGas: '0x' + (2n  * 1_000_000_000n).toString(16),
  type: 2
};

const resp = await fb.sendPrivateTransaction({ transaction: tx, signer: Wallet.fromMnemonic(process.env.MNEMONIC) }, { maxBlockNumber: (await provider.getBlockNumber()) + 5 });

const res = await resp.wait();
if (res === FlashbotsTransactionResolution.TransactionIncluded) console.log('Included via Protect');

This honors the signed private-transaction requirement and avoids mempool exposure while ensuring non-zero tips per Protect guidance. (docs.flashbots.net)

Layer 2: Intent-based execution (return MEV to users)

• UniswapX: Gas-free, auction-based fills with per-chain auction mechanics (e.g., RFQ→exclusive Dutch on Ethereum, open Dutch on Arbitrum). By design, fillers compete and MEV is delivered as price improvement; failed swaps cost users nothing. Integrate UniswapX for large or volatile pairs to compress slippage and shift MEV from adversaries to users. (docs.uniswap.org)
• CoW Protocol: Batch auctions with uniform clearing prices eliminate sequencing sensitivity within the batch and systematically block sandwiches; combine with MEV Blocker OFA for further privacy/rebates. (docs.cow.fi)
• Uniswap Wallet “swap protection”: If you own the wallet UX, keep swap protection on by default (routes to Protect). This alone cuts public mempool exposure for retail flow. (support.uniswap.org)

Layer 3: AMM-level mitigations (Uniswap v4 hooks)

• Anti-sandwich fee hooks: Dynamically raise fees when deltaTick suggests adversarial price impact; several v4 hooks implement quadratic fee curves within beforeSwap/afterSwap to make sandwiches unprofitable while keeping normal swaps cheap. Audit attention is required—OpenZeppelin’s review of v4 hooks found multiple high/critical issues in 2025. (ethglobal.com)
• Call/batch auction hooks: Hyperbolic call auctions or “uniform price” settlement within a short window neutralize ordering advantages without adding oracles. (ethglobal.com)
• Governance runway: Uniswap Foundation’s Hook Design Lab is funding production-grade policy orchestration (KYC, MEV protection, dynamic fees) to standardize hook composition—plan upgrades against that interface. (uniswapfoundation.org)

Example (v4 hook sketch): Raise fee on abnormal tick jump

function beforeSwap(address, PoolKey calldata key, IPoolManager.SwapParams calldata params, bytes calldata) 
  external returns (bytes4, BeforeSwapDelta, uint24 hookFee) 
{
    int24 currentTick = getTickFromSqrtPrice(poolState[key].sqrtPriceX96);
    int24 dt = currentTick - poolState[key].lastTick;

    // quadratic fee growth on abnormal jumps
    uint24 base = 5; // 5 bps
    uint24 maxf = 60; // 60 bps cap
    uint24 dyn = uint24(min(uint256(base) + (uint256(abs(dt))**2)/1e4, uint256(maxf)));

    poolState[key].lastTick = currentTick;
    return (this.beforeSwap.selector, BeforeSwapDeltaLibrary.ZERO_DELTA, dyn);
}

This pattern penalizes outlier price moves likely associated with sandwiches while preserving Gas optimization (no external calls). Audit and gas profiling are mandatory in production.

Layer 4: Transaction-level guardrails

• Tight slippage + short deadlines: Keep slippage bands pair-specific and decay them under high volatility; enforce deadlines under 60–120s. Combine with sqrtPriceLimitX96 bounds on v3/v4 paths to eliminate pathological fills.
• Revert protection: For retail UX, default to Protect/MEV Blocker endpoints with revert protection (e.g., /noreverts or /fullprivacy) for sensitive flows. (mevblocker.io)
• Builder diversity: Don’t pin to a single builder; use Protect settings to specify additional builders. Monitor relay health and builder market share weekly. (collective.flashbots.net)

Layer 5: Monitoring and incident response

• Stream hints: Subscribe to the MEV-Share SSE to detect cluster activity around your pairs; if abnormal, auto-escalate to /fullprivacy and disable nonessential hints until the window passes. (docs.flashbots.net)
• Sandwich meter SLOs: Target <0.10% of swaps flagged as sandwiched, measured via backrun clustering and tick-spike heuristics. If SLO breaches, trigger a temporary switch to intent-only routing and raise hook fees.
• Reporting: Display “MEV rebates credited” and “price improvement vs baseline” in your app; this both proves value and discourages end-user slippage bloat.

Proof — what “good” looks like in metrics, with sources

• Price improvement: Order-flow auctions (CoW/UniswapX) have measurable price improvement, with peer-reviewed work documenting 4–5 bps uplift in sample sets. Your KPI: deliver 3–6 bps against your pre-integration baseline on eligible pairs. (arxiv.org)
• Attack surface reduction: With Protect/MEV-Share and MEV Blocker, sensitive data (like slippage) is hidden; only partial hints are disclosed. For high-value orders run /fullprivacy (no rebates). Your KPI: reduce public-mempool routing to single-digit percent for swaps >$10k. (writings.flashbots.net)
• Builder-aware resilience: Given that ~90% of blocks are MEV-Boost and builder concentration persists, your best defense is to internalize MEV via OFAs and hooks while diversifying builders and using private routing. Your KPI: zero user-visible “sandwich loss” incidents during known volatility windows (CPI prints, token listings). (blog.rated.network)
• Reality check: Private routing is not absolute. MEV Blocker’s own guidance warns of reorg leakage on ~0.1% of transactions; recent research also confirms the existence of sandwiches on private channels—hence the need for layered defenses (intents + hooks + private). Your KPI: ensure fallback policies engage automatically during reorg spikes. (mevblocker.io)

Emerging practices to track (next 2–3 quarters)

• ePBS (EIP‑7732) and inclusion lists (EIP‑7547): Monitor EF timelines for Glamsterdam; design for “OFA + ePBS” compatibility. Inclusion lists strengthen censorship resistance but won’t eliminate sandwich incentives by themselves. (blog.ethereum.org)
• Uniswap v4 ecosystem: Expect standardized “policy orchestration” frameworks and broader audits of anti-MEV hooks. Budget time for migration tests and hook audits before turning on dynamic fees in production. (gov.uniswap.org)

How 7Block Labs executes (pragmatic, procurement-ready)

• Design and integration
  • We audit your current routing and swap paths, then implement a staged rollout: Protect/MEV-Share first, MEV Blocker endpoints for specific cohorts, then UniswapX/CoW integration per pair/chain.
  • For AMMs or app-specific pools, we implement and audit v4 anti-sandwich hooks with bounded gas overhead.
  • We deliver a builder policy: allowed relays/builders, auctionTimeout policies, and hint templates per order-size bucket. (docs.flashbots.net)
• Tooling and automation
  • Pre-trade simulation + post-trade reconciliation with “sandwich meter” dashboards.
  • Auto-escalation of privacy levels using MEV-Share SSE signals and pool-level anomaly detectors. (docs.flashbots.net)
• Governance and compliance
  • Runbooks for incident response (reorg spike, builder outage).
  • Quarterly reviews to adapt to EF timelines on ePBS/inclusion lists. (blog.ethereum.org)

Practical examples you can ship this sprint

• Wallet/Frontend: Default to Protect RPC; expose a “Stealth Mode” toggle that maps to /fullprivacy for one-off high-value swaps. Note the signed-private-tx requirement post-Nov 2025. (collective.flashbots.net)
• Aggregator: Route orders above a volatility-adjusted threshold to UniswapX; otherwise, route to AMM with Protect RPC. On Arbitrum, rely more on open Dutch auctions (fast decay). (docs.uniswap.org)
• DEX/Pool operator: Add a deltaTick-sensitive fee hook and enforce sqrtPrice limits; run a canary pool with call-auction settlement during known volatility events (listings, oracle recalc windows). (ethglobal.com)

Where this lands financially (ROI you can show)

• Example math: On $100M monthly volume, 4 bps improvement returns $40,000/month to users; capturing 30% of backrun rebates adds another line of revenue depending on flow mix. MEV-Share defaults to refunding users while compensating validators/searchers; you can tune distributions per business model. (arxiv.org)
• Operational savings: Private routing with revert protection eliminates failed-tx gas for protected flow; UniswapX gas-free trades shift cost to fillers. Your finance team will see this in LTV:CAC and support ticket reductions. (docs.uniswap.org)

How we work together

• Architecture and integration: Our DeFi development services team handles Protect/MEV-Share, MEV Blocker, UniswapX, and CoW wiring with staged rollouts.
• AMM and hooks: Our smart contract development group implements and audits Uniswap v4 hooks designed for sandwich resistance, with test harnesses and gas profiling.
• Security and audits: Independent review via our security audits focuses on hook invariants and failure modes.
• Protocol and integration: For DEXs and venues, our DEX development and blockchain integration practices ensure consistent routing and data pipelines across chains.
• Full-stack support: If you’re building intent systems or cross-chain routing, we align with your roadmap through custom blockchain development services, web3 development, and cross-chain solutions.

Appendix: Why the stack works (engineering rationale)

• Market structure: With MEV-Boost dominance and builder concentration, exclusive order flow (EOFO) and OFAs are the only practical levers to turn adversarial MEV into user price improvement today. Your stack must assume off-protocol PBS for at least the next product cycle and be “ePBS-compatible” later. (blog.rated.network)
• Privacy model: MEV-Share minimizes data leakage (hash + pool hints by default); MEV Blocker adds OFA with configurable privacy and explicit endpoint semantics. Both feed major builders directly, decreasing inclusion latency while avoiding the public mempool. (writings.flashbots.net)
• Execution model: Intent auctions (UniswapX, CoW) reward fillers/solvers for best execution; batch or Dutch mechanics compress the adversary’s window, and uniform clearing prices slash sequencing profits. (docs.uniswap.org)
• AMM-level friction: v4 hooks change attacker economics. If a would-be sandwich pushes dt beyond a threshold, dynamic fees erase their edge; call auctions remove ordering leverage altogether. This is controllable, auditable Solidity—not wishful thinking. (ethglobal.com)

Caveats (so you don’t get surprised)

• Private != perfect: Reorgs and edge-case leakage still exist; research confirms some private-path sandwiches. Build monitors; auto-escalate privacy levels during stress. (mevblocker.io)
• Hooks need audits: Recent audits of v4 hooks found high/critical issues; do not ship unaudited MEV hooks. (openzeppelin.com)
• Config drift is real: Keep Protect/MEV-Share settings current with the latest signing and endpoint requirements; stale configs silently disable protections. (collective.flashbots.net)

If you want 7Block Labs to implement this stack end‑to‑end—with clear KPIs, dashboards, and a pilot in production—start here: Book a 30-Day DeFi MEV Pilot.