OAK — OnChain Attack Knowledge

Worked example · 2026-11

Loopscale — a week-long API probing campaign found two paths: collateral valued as a different asset (undercollateralized SOL loan) and a high-interest loan sold into a vault to inflate its NAV — Loopscale Genesis Vaults / Solana — 2026-11-05

Loss
$0 user loss per Loopscale ("Affected vaults have been made whole and no user deposits have incurred a loss"). Attempted extraction per Loopscale's 2026-11-06 update: an undercollateralized loan of ~$412K from the SOL Genesis Vault, and a disproportionate redemption of ~$521K from the USDC Genesis Vault "which our systems halted within 30 seconds of transaction generation". Loopscale does not say how the vaults were made whole or by whom. The $412K and $521K figures are Loopscale's own; the 4,598.434180621 SOL in the unwind transaction below is traced by OAK.
OAK Techniques observed
OAK-T9.016 (Contract Accounting / State-Invariant Flaw — primary, operator-stated. Both paths made the protocol's own books wrong in the caller's favour: path 1 a misconfigured combination of asset-pricing parameters made deposited collateral be "valued as a different asset"; path 2 an atomic bundle sold a loan "carrying an extreme interest rate" into the USDC Genesis Vault, which inflated the vault's NAV and let a redemption take more than the redeemer's share. See techniques/T9.016-contract-accounting-state-invariant-flaw.md). No separate Technique fits the API probing phase: Loopscale says the attacker targeted "publicly inspectable program logic and private transaction-building APIs" with more than 30,000 malicious requests a day, but does not say what the requests did; OAK records this as undisclosed rather than forcing a fit.
Attribution
unattributed. Loopscale calls the actor "sophisticated" and published four addresses (two Solana, two EVM) "identified in connection with this activity"; it has not named anyone and says it is working with federal law enforcement.
Key teaching point
A lending vault must check, at the moment it accepts a loan or collateral, that the asset identity and the interest rate fall inside bounds the vault itself enforces, rather than trusting parameters assembled by an off-chain transaction builder. Both paths used inputs the protocol accepted as valid (a pricing-parameter combination, a loan with an extreme rate) that no on-chain bound rejected. A cap on the rate of any loan a vault will buy, and a check that the pricing identifier matches the deposited mint, would have broken each path at its first step.

Summary

Loopscale is a Solana lending protocol; its SOL and USDC Genesis Vaults hold depositors' funds that are lent to borrowers. On 2026-11-05 at 10:13 UTC it announced that it had been targeted "over the past week" by a sophisticated actor whose requests hit its APIs more than 30,000 times a day, that it had paused the protocol after an escalation, and that the vaults had been made whole. On 2026-11-06 it described the two paths. First, against the SOL Genesis Vault, a misconfigured combination of asset-pricing parameters caused deposited collateral to be valued as a different asset, enabling an undercollateralized loan of about $412K. Later, an atomic bundle sold a loan with an extreme interest rate into the USDC Genesis Vault, inflating its NAV and enabling a redemption of about $521K that Loopscale's systems halted within 30 seconds of transaction generation. Third-party coverage (Rektradar) gives the worked example as 1 kySOL treated as a zBTC identifier. OAK's own read of one Solana transaction shows 1 kySOL and 4,598.434180621 SOL moving on 2026-11-03, which is consistent with an unwind of the SOL loan. This is a different incident from the April 2025 RateX pricing exploit (related: 2025-04-loopscale.md).

Timeline (UTC)

Flaw: pricing parameters and loan purchases are accepted without on-chain bounds. Preparation: a week of API probing. Take: two paths, SOL vault then USDC vault. Money: the SOL loan is unwound; the USDC redemption is halted. Response: pause, statement, staged restore. Times for the statements are from the X posts; Solana times are from block times.

When What happened OAK
Before 2026-11 (since when: undisclosed) Loan pricing parameters can be combined so that collateral is valued as another asset, and a vault will buy a loan with an extreme interest rate; neither is bounded on-chain. Loopscale calls both "publicly inspectable program logic" reached through "private transaction-building APIs". T9.016
About 2026-10-29 to 2026-11-05 (exact start undisclosed) Sustained campaign: more than 30,000 malicious API requests per day. What the requests did is undisclosed. —
2026-11-01 19:33:31 to 19:52:38 Eight Solana transactions on a Loopscale-published address (247Lk5YNH9URfBBvxVUtDruz8GvGX8gKGuYHVCZThpiR), first 2BzqTxMSha1HtURY7mMXssgPsyMb3xFiifataqzUUHh8kLbVXGPmKWh1qhQ92ypn6S4asvUgBp1zVWmpusSmHY6k, last 5r2GNcEpiJaNmzNB5QVR5wv1LsXa9gWMwJcnLmFigFd1XqaN4RKqtCvyGwpNhETWtKBvo7tzZLy55sgRpYTAkx7d. The last is a system-program-only transaction with no token movement. OAK did not decode the others; their purpose is undisclosed. This is the only activity on that address and is the best available preparation signal. —
2026-11 (date and time undisclosed) Path 1: against the SOL Genesis Vault, collateral is valued as a different asset (Rektradar: 1 kySOL treated as a zBTC identifier) and an undercollateralized loan of about $412K (reports: about 4,597 SOL) is taken. No transaction hash is published. T9.016
2026-11-03 13:43:50 Traced by OAK: in 47zp5i14ERm2soQQGLs5LKRk4Xi2Yigh6iuJ68URKe4VfzC9u2GpgWYbLG73fT4a645GBnUibZ5gP69kfaD7DbAo, a call to the Loopscale program 1oopBoJG58DgkUVKkEzKgyG9dvRmpgeEm1AVjoHkF78, signer rektbdF5r7HnWrPDRvD76pC1V9rVfaGmbSY3Dsrj8Kx sends 4,598.434180621 SOL into a wrapped-SOL account owned by 8oCX3kkgviLPxYGBfSt1kCKWVmHer1pHqutPTiBYnGpu, and 1 kySOL moves from escrow-side owner Gb2qCYLs3dEy6D4TvdLYr7wRDMMWDCPR9oK5SzNa5Gtn to the signer. The size matches Loopscale's "later liquidation returned roughly the same SOL amount" (Rektradar). That this is the path-1 loan, and that 8oCX… is the SOL Genesis Vault, are inferences by OAK, not stated by a source. T9.016
2026-11 (later; date and time undisclosed) Path 2: an atomic transaction bundle sells a loan with an extreme interest rate into the USDC Genesis Vault, inflating its NAV; a redemption of about $521K is generated. Loopscale's systems halt it within 30 seconds of transaction generation, so it does not settle. T9.016
2026-11-05 (time of pause undisclosed) Loopscale's systems detect "a significant escalation" and the protocol is paused. response
2026-11-05 10:13:27 Loopscale announces the campaign, the pause, that vaults were "made whole", and publishes four addresses. response
2026-11-06 00:34:00 Update: priority loan functions restored (collateral top-ups, repayments except for USDC Genesis Vault loans, collateral withdrawal for fully repaid loans). Vault withdrawals stay restricted. Loopscale says both paths are "identified and contained" and gives the $412K and $521K figures. response
Not published Post-mortem, fix details, how vaults were made whole, transaction hashes for the two paths, law-enforcement outcome. undisclosed

Key addresses (the four are Loopscale-published; the Solana role labels are OAK's):

Fund flow

Traced by OAK on 2026-11-10 with the Solana public RPC (tools/explorer.py does not read Solana transactions, so getTransaction was called directly). The one hop below was read from the transaction's parsed instructions. The loan itself, the USDC redemption, any proceeds and the EVM addresses carry no traced edges: no transaction hashes were published, the Blockscout address lookups for the two EVM addresses returned HTTP 500, and the two addresses only show balances.

All transfers as a table (1)
Time (UTC)FromToAmountOAKTxBasis
2026-11-03T13:43:50ZSigner of 2026-11-03 unwind tx (attacker status not stated)
rektbdF5r7HnWrPDRvD76pC1V9rVfaGmbSY3Dsrj8Kx		Owner of wSOL account that received 4,598 SOL (likely SOL Genesis Vault, inferred)
8oCX3kkgviLPxYGBfSt1kCKWVmHer1pHqutPTiBYnGpu		4,598.4342 SOLT9.01647zp5i14ERm2soQQGLs5LKRk4Xi2Yigh6iuJ68URKe4VfzC9u2GpgWYbLG73fT4a645GBnUibZ5gP69kfaD7DbAotraced by OAK

Root-cause evidence

  • Technique: OAK-T9.016
  • Source: https://x.com/Loopscale/status/2118502123705159769; https://x.com/Loopscale/status/2118285556123611378
  • Source type: operator
  • Confidence: confirmed
  • Evidence: Loopscale's own 2026-11-06 update states both mechanisms: collateral valued as a different asset via "a misconfigured combination of asset-pricing parameters" (SOL Genesis Vault, $412K loan), and a loan "carrying an extreme interest rate" sold into the USDC Genesis Vault to inflate NAV ($521K redemption, halted). The operator source is why this is confirmed; the fine detail (which parameters, which program instruction, why the extreme-rate loan is accepted at its face value) is not published, and the kySOL/zBTC example comes from Rektradar, not Loopscale. The T9.016 label is OAK's classification of the operator's description.

What is not known

  • Dates and transaction hashes of the two paths, and exactly how the $0-loss outcome was reached.
  • What the 30,000-per-day API requests did, and whether the "private transaction-building APIs" were Loopscale's own endpoints.
  • Whether the attacker held or received any funds; the EVM addresses' role.
  • Total campaign scope: Loopscale said it would not resume normal operations until it had established it.

Mitigation (for the Technique page)

Not added to techniques/T9.016-contract-accounting-state-invariant-flaw.md or the mitigation files in this run (single-file task). Proposed bullet: On-chain bounds on what a vault will buy or accept (new mitigation, in the form of OAK-M11 and OAK-M38). What: the vault program rejects a loan whose rate is above a configured maximum, and rejects collateral whose pricing identifier does not match the deposited mint; and caps single-transaction NAV change and redemption size. How: enforced inside the program the vault runs, not in the API that builds transactions, so a crafted transaction cannot skip it. Why: in this incident the attacker assembled parameters off-chain and the on-chain program accepted them; a rate ceiling stops the NAV inflation at the step the loan is sold into the vault, and an identity check stops kySOL being priced as zBTC. A redemption cap would also have bounded the $521K attempt even if Loopscale's off-chain monitor had not halted it within 30 seconds.

Public references

Techniques demonstrated (1)