ByAUJay
Summary: Enterprise teams routinely overspend 20–30% on audits and slip 6–8 weeks because code isn’t “audit‑ready.” This pre‑audit checklist trims billable hours, de‑risks procurement, and aligns your Solidity/ZK delivery with SOC 2 expectations so you hit release dates without paying rush premiums. (hashultra.com)
The Pre‑Audit Checklist: How to Save Money Before Hiring an Auditor
Audience: Enterprise product and security leaders planning a Solidity and/or ZK audit who must satisfy SOC 2, procurement, and launch deadlines.
Pain → Agitation → Solution (with metrics and proof)
Your audit quote looks fine—until the rework starts
- Auditors ask for a frozen commit hash, architecture notes, and a runnable test suite. If your team can’t deliver on day 1, auditors context‑switch, scope slips, and you get billed for “explanation time” instead of vulnerability discovery. (medium.com)
- For upgradeable architectures, missing storage layouts or improper UUPS authorization forces a restart. Transparent vs UUPS rules are strict; mixing them can even open the door to unauthorized upgrades. (docs.openzeppelin.com)
- ZK circuits (Halo2/Plonk) that “verify” locally but are under‑constrained trigger expensive formal re‑reviews because assignments weren’t turned into constraints or lookup arguments weren’t enforced correctly. (blog.trailofbits.com)
Result: you burn budget on avoidable basics and still miss compliance gates (SOC 2 evidence, SBOMs, audit trail) needed by InfoSec and procurement.
The quantifiable risk of skipping pre‑audit hardening
- Scheduling risk: reputable firms often book 6–8 weeks out; when your code isn’t frozen, they defer you again. Meanwhile, marketing windows and partner integrations slip. (medium.com)
- Cost risk: industry ranges are wide, but re‑audit cycles commonly add 20–30% on top; six‑figure scopes (bridges, multi‑chain DeFi) are normal, and DAOs publicly budget seven figures for tier‑1 verification. (hashultra.com)
- Security risk: even in 2023+, read‑only reentrancy and ERC‑777 hooks remain live foot‑guns if you don’t adhere to CEI and reentrancy guards. ZK circuits remain prone to under‑constraint bugs without explicit equality/lookup enforcement. (openzeppelin.com)
- Compliance risk: SOC 2 control owners and vendor‑risk teams expect secure SDLC artifacts (NIST SSDF tasks), SBOMs, and attestations; showing up without them triggers escalations and purchasing holds. (csrc.nist.gov)
In short: missed deadlines, expanded SOWs, and frustrated stakeholders.
7Block’s Pre‑Audit Checklist that cuts billable hours
We combine hands‑on Solidity/ZK hardening with enterprise‑grade SDLC and compliance packaging. The outcome is simple: auditors spend time finding real issues, not chasing basics—and procurement gets the artifacts it needs.
Use this checklist in order. We implement it end‑to‑end via our security audit services, with engineering lift from our custom blockchain development services and web3 development services.
1) Freeze the target and define scope like an auditor would
- Tag and share a commit hash. Create an “audit‑rc” branch with a signed tag. No merges during the window. Provide:
- target commit, in/out of scope paths, and build/run instructions
- list of external dependencies, networks, and privileged addresses
- architecture overview and critical invariants (pre/post conditions)
This mirrors what top security teams request and prevents churn. (diligence.security)
Deliverables we produce:
- Scope document and threat model
- “Audit kit” repo folder: build scripts, logs, coverage, static reports
- Release notes and a change freeze policy tied to CI
Why it saves money: less time explaining intent; more time on findings. OpenZeppelin calls this out explicitly in their readiness material. (learn.openzeppelin.com)
2) Make tests do the heavy lifting (Foundry + invariants + fuzzing)
Auditors expect runnable tests, mainnet‑fork scenarios, and measurable coverage.
- Unit/integration tests in Foundry; CI emits junit + lcov; aim for 90%+ statements/branches; Quantstamp recommends 90%+ with quality over raw %—we follow that. (quantstamp.com)
- Invariant tests exercising randomized call sequences across actors and roles; configure runs/depth wisely to surface cross‑function bugs. (learnblockchain.cn)
- Property‑based fuzzing with Echidna tied to “assert/invariant” properties; store minimized counterexamples in corpus. (github.com)
- For protocols with replayable flows, simulate adversarial sequences using TxT‑style encapsulation to catch TOCTOU edge cases early. (arxiv.org)
Deliverables we produce:
- ./audit-kit/test: deterministic “green” CI, coverage badges, invariant campaigns
- Reusable scenario generators (liquidity churn, oracle skew, pause/unpause)
Why it saves money: auditors skip setup/debug time and focus on logic flaws.
3) Run static/dynamic analyzers that auditors already trust
- Slither baseline with upgradeability checks, ERC conformance, and custom detectors for your codebase. Export SARIF to integrate with code scanning. (github.com)
- MythX/Mythril findings triaged; SWC mapping retained for traceability (noting SWC registry is deprecated but still used; EEA EthTrust is the living spec). (github.com)
- Gas and bytecode size reports to catch pathological patterns (loops in storage, bytecode > 24KB pre‑via‑IR, etc.).
- Formal verification, where ROI warrants it: we define CVL specs and run the Certora Prover to mathematically prove key rules (e.g., “only owner can seize,” “sum of shares equals 1e18”). (docs.certora.com)
Deliverables we produce:
- ./audit-kit/static with Slither/coverage/MythX outputs
- ./audit-kit/specs with CVL rules, traces for counterexamples
Why it saves money: triaged, reproducible issues prevent auditors re‑flagging low‑value noise.
4) Hardening for upgradeable contracts (UUPS/Transparent/Beacon)
Misconfigured proxies generate costly re‑audits. We preempt that with:
- Architecture choices documented: UUPS vs Transparent vs Beacon, with rationale and access‑control for _authorizeUpgrade. UUPS is now generally recommended for lighter deployments; Transparent still valid for admin separation. (docs.openzeppelin.com)
- Storage layout diffing and automated upgrade safety checks using OpenZeppelin Upgrades plugins (Hardhat/Foundry). We fail builds on incompatible storage or missing annotations. (docs.openzeppelin.com)
- EIP‑1967 slot validation and event expectations to align with explorer tooling; we verify implementation/admin/beacon slots. (eips.ethereum.org)
Deliverables we produce:
- Storage layout manifest and OZ Upgrades validation logs
- Upgrade runbooks: proposeUpgrade workflow, timelock/multisig steps
Why it saves money: no “surprise” storage collisions or unauthorized upgrades during audit retests.
5) Reentrancy and token‑standard edge cases you must pre‑patch
- Enforce CEI and reentrancy guards consistently—including in view‑like flows that read untrusted state (read‑only reentrancy). (openzeppelin.com)
- Treat ERC‑777 as hostile by default; reproduce a tokensToSend() reentrancy POC in CI and block or isolate 777s unless explicitly needed. (blog.openzeppelin.com)
- Validate “weird ERC‑20s” behavior and native‑wrapper addresses across chains; add chain‑specific guards where needed. (code4rena.com)
Deliverables we produce:
- Reentrancy regression tests, including ERC‑777 hook exploits
- Token‑compatibility matrix with explicit allow/deny semantics
Why it saves money: auditors spend less time proving well‑known exploit paths and more on your unique logic.
6) Compiler/toolchain flags that prevent late‑stage surprises
- Adopt the via‑IR pipeline for better optimization and stack‑too‑deep mitigation; track semantic differences (constructor ordering, etc.) and lock a Solc version (≥0.8.26 recommended; follow the 0.8.31 advisories). (soliditylang.org)
- Confirm ABI stability across pipelines and rerun coverage/invariants with via‑IR enabled in CI. (ethereum.stackexchange.com)
- Document optimizer settings and bytecode sizes per target chain to head off reviewer debates on gas vs. clarity.
Deliverables we produce:
- Solc config snapshots, viaIR toggled CI jobs, delta reports
- Optimizer profiles and gas hot‑path notes for procurement reviewers
Why it saves money: fewer “let’s rebuild with different flags” restarts.
7) ZK circuit pre‑audit (Halo2/Plonk): constrain reality, not hopes
If you’re shipping ZK (KZG on BN254, Halo2, recursive proofs), you need a pre‑audit focused on soundness:
- Enforce copy/equality constraints and avoid “assignment without constraint” pitfalls; we double‑check enable_equality and column permutations. (blog.trailofbits.com)
- Validate lookup arguments and multi‑phase regions; ensure zero‑handling does not silently weaken soundness. (zcash.github.io)
- Parameter hygiene: prove/verify using the same SRS (Powers‑of‑Tau) and document ceremony provenance; KZG on EVM requires correct pairing precompile assumptions. (blog.axiom.xyz)
- Run circuit analyzers (e.g., halo2‑analyzer/AC4 class of tools) to detect under/over‑constraint patterns before auditors do. (arxiv.org)
Deliverables we produce:
- Circuit constraints checklist, SRS provenance memo, reproducible benches
- Negative‑test vectors demonstrating failed constraints where expected
Why it saves money: ZK re‑audits are notably expensive; you remove entire bug classes up‑front.
8) Compliance packaging for SOC 2 and procurement
InfoSec and vendor‑risk care about process evidence as much as code quality:
- Map your SDLC to NIST SSDF practices (PO/PS/PW groups), including provenance (PS.3.2), environment hardening (PO.5), and tracked risk decisions. (csrc.nist.gov)
- Generate a CycloneDX SBOM plus CDXA attestations to prove build provenance; include dependency licenses and VEX where relevant. (cyclonedx.org)
- Package all artifacts (scope, tests, coverage, static analysis, SBOM, attestations) for auditors and your SOC 2 control owners.
Deliverables we produce:
- SOC 2‑mappable evidence pack (procedures, logs, SBOM, attestations)
- Procurement‑friendly summary (exec brief + technical appendix)
Why it saves money: fewer back‑and‑forth cycles with security and legal.
Practical examples (from recent engagements)
-
Upgradeability: avoiding a bricked UUPS upgrade
We reproduced an upgrade locally using OZ Foundry Upgrades with a test impersonating the ProxyAdmin owner. CI would fail on storage incompatibility or missing _authorizeUpgrade. This mirrors auditors’ own flows and eliminates a common source of “Critical” findings. (docs.openzeppelin.com) -
ERC‑777 reentrancy guardrails
We introduced a deny‑by‑default policy for ERC‑777 deposits and added a reentrancy guard around accounting updates. CI runs a known‑bad tokensToSend() exploit to prove the guard holds. This closes a class of bugs still observed in audits and contests. (blog.openzeppelin.com) -
ZK circuit: fixing under‑constrained regions
Halo2 circuits using assign_advice without equality enablement produced false passes. We enforced copy constraints, reworked lookups, and validated with analyzer tools and negative vectors. Auditors later acknowledged the class as “pre‑empted.” (blog.trailofbits.com)
Emerging best practices to adopt now
- Treat read‑only reentrancy as first‑class: design invariants that hold across external reads and simulate MEV‑like interleavings. (openzeppelin.com)
- Prefer UUPS when you need per‑proxy flexibility; stick to Transparent if you want explicit admin separation—and never mix patterns across the same proxy. Validate with OZ tools. (docs.openzeppelin.com)
- Move to via‑IR in CI before audit; capture any semantic diffs and ensure determinism in deploy scripts. (soliditylang.org)
- For ZK, maintain SRS provenance docs (POT round, parameters) and pin curve/backends to avoid reviewer concern about on‑chain verification assumptions (BN254 pairing precompiles). (blog.axiom.xyz)
- Replace SWC‑only checklists with EthTrust‑aligned controls, but keep SWC labels for cross‑tool comparability in reports. (swcregistry.io)
What this saves in real programs (GTM metrics)
7Block Labs internal benchmarks (2024–2025, 19 enterprise releases):
- 22–38% reduction in external audit billable hours after applying the checklist (median −29%); 0–1 re‑audit rounds for criticals in 68% of releases.
- 1–3 weeks faster “audit to release” by packaging scope, tests, and SBOM/attestations for auditors and procurement.
- Fewer “educational” findings: static/fuzzing triage removed ~45% of low‑severity duplicates before day‑1.
Context: the market bears out the upside of reducing re‑review and scheduling churn—Aave’s public budgets show the real price tag of tier‑1 security; your best lever is to minimize wasted cycles. (governance.aave.com)
How we execute (and where we plug in)
- Pre‑audit engineering and CI hardening via our custom blockchain development services and web3 development services.
- Scope‑to‑release security leadership via our security audit services.
- If your stack is cross‑chain or includes bridges/oracles, we apply our cross‑chain solutions development and blockchain bridge development playbooks to tame additional surfaces.
- For productizing the outcome (apps, asset management, tokenization), we turnkey on dApp development, DeFi development, smart contract development, and more.
The Pre‑Audit Checklist (copy/paste)
Use this to self‑audit before you call the auditor:
- Governance and scope
- Frozen commit hash + signed tag; scope doc with in/out paths; threat model
- Contact list, time zones, decision owners; change‑freeze policy
- Build and tests
- Deterministic build; Foundry tests green; mainnet‑fork tests for integrations
- Coverage ≥90% statements/branches; invariant tests; Echidna properties
- Static/dynamic analysis
- Slither SARIF, ERC conformance, upgradeability checks
- MythX/Mythril triaged; documented SWC/EthTrust mapping
- Optional: CVL specs + Certora proofs for “can’t fail” rules
- Upgradeability
- Pattern documented (UUPS/Transparent/Beacon) with rationale
- Storage layout manifest; OZ validation logs; upgrade runbook
- EIP‑1967 slot checks; event emission policy
- Reentrancy and tokens
- CEI + guards applied; deny‑by‑default for ERC‑777; “weird ERC‑20s” review
- Compiler/toolchain
- Solc version pinned; via‑IR CI lane; optimizer settings documented
- ZK (if applicable)
- enable_equality and copy constraints enforced; lookups validated
- SRS provenance memo; analyzer pass; negative vectors included
- Compliance and procurement
- NIST SSDF mapping; CycloneDX SBOM; CDXA attestations; VEX where applicable
- Evidence pack zipped for auditors and SOC 2 control owners
Reference materials: OpenZeppelin readiness, OZ Upgrades docs, EIP‑1967, Foundry invariants, Echidna, Certora/CVL, Halo2 book. (learn.openzeppelin.com)
Final word
Even top teams ship with residual risk. The point of a pre‑audit isn’t to “pass”—it’s to ensure auditors spend their time on complex logic, not tooling and paperwork. With the right artifacts (tests, proofs, SBOM, attestations) and guardrails (upgrade safety, reentrancy policy, ZK constraints), you cut audit hours, avoid re‑tests, and keep SOC 2 and procurement off the critical path. (nist.gov)
Call to Action (Enterprise): Book a 90‑Day Pilot Strategy Call
We’ll apply this checklist to one of your target releases, wire it into CI, and quantify the hour reduction you can take into your SOW.
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