Worked example · 2021-04

EasyFi admin-key compromise — Polygon — 2021-04-19

Loss: approximately $59M (~6M EZ tokens drained from the EasyFi treasury and team-multisig + ~$6M USDC / DAI / USDT drained from EasyFi liquidity provisions and lending pools).
OAK Techniques observed: OAK-T4.003 (Private-Key Theft — EasyFi founder Anshul Dhir's MetaMask key was compromised, granting the attacker the admin key's full authority over EZ minting and LP reserve access). OAK-T11.002 (admin-key compromise — EasyFi founder Anshul Dhir's MetaMask key was compromised) + OAK-T9.004 (post-compromise access-control abuse; the compromised admin authority was used to mint EZ from team-treasury and drain LP and lending pool reserves) + OAK-T5.001 (downstream hard-LP-drain dump of stolen EZ on Uniswap and QuickSwap).
Attribution: pseudonymous; partial recovery via Polygon team coordination; the EasyFi protocol relaunched as "EasyFi V2" with operator-funded compensation framework for affected token holders.
Key teaching point: Single-EOA admin authority over a treasury-and-liquidity-pool-controlling contract is a custody-side anti-pattern. EasyFi's founder held a single MetaMask EOA with retained mint-and-treasury-authority over the EZ token contract; compromise of that single key produced cumulative-loss across multiple distinct extraction surfaces (treasury mint + LP drain + lending-pool drain). The case is the canonical foundational 2021 worked example for the OAK-M37 HSM/MPC custody class as a mitigation for single-EOA-admin-authority anti-patterns and pairs with Spartan Protocol May 2 + PancakeBunny May 19 to give the April-May 2021 BSC-and-Polygon DeFi exploit cohort a three-case structural articulation across three distinct attack-class subclasses.

Summary

EasyFi is a Polygon-and-Ethereum lending protocol that issued the EZ governance token. On April 19, 2021, founder Anshul Dhir's MetaMask EOA private key was compromised — the specific compromise vector was not publicly detailed beyond "the key was extracted from the founder's MetaMask wallet" but was consistent with operator-side host compromise rather than upstream-vendor compromise. The attacker used the compromised admin authority to (a) transfer approximately 2.98 million EZ tokens from the EasyFi team treasury to attacker-controlled addresses, (b) mint additional EZ to the attacker's address up to a cumulative ~~6 million EZ outflow (~~$54M nominal pre-dump), and (c) drain approximately $6M in USDC / DAI / USDT from EasyFi's lending pool reserves on Polygon. The attacker dumped the stolen EZ on Uniswap and QuickSwap, crashing the EZ token price by approximately 80% in the same-day window.

EasyFi's response involved Polygon team coordination, partial recovery through emergency-pause of the affected contracts, and a subsequent EasyFi V2 relaunch with an operator-funded compensation framework for affected pre-event token holders. The case is the canonical foundational 2021 Polygon-DeFi worked example for the single-EOA-admin-authority compromise class.

Timeline (UTC)

When	Event	OAK ref
2021-04-19 (early UTC)	Attacker compromises EasyFi founder Anshul Dhir's MetaMask EOA key	T11.002 (initial-access)
2021-04-19	Attacker uses admin authority to transfer ~2.98M EZ from team treasury and mint additional EZ to attacker addresses	T9.004 (extraction; mint authority abuse)
2021-04-19	Attacker drains ~$6M USDC/DAI/USDT from EasyFi lending-pool reserves	T5.001 (LP drain)
2021-04-19	Attacker dumps stolen EZ on Uniswap + QuickSwap; EZ price drops ~80%	T5.001 (downstream dump)
2021-04-19 (within hours)	EasyFi team identifies compromise; emergency-pauses the affected contracts; publicly discloses	M34 (operator response)
2021-04-19 to 2021-04-20	Polygon team coordination; partial recovery efforts via emergency-pause of LP-pool reserves before full drain	(operator response)
2021-Q2 to Q3 onward	EasyFi V2 relaunch; operator-funded compensation framework for pre-event holders	(recovery; partial)

What defenders observed

Pre-event (single-EOA admin authority anti-pattern visible). EasyFi's authority-graph was publicly documented; defenders auditing the protocol pre-event could have observed that a single founder-EOA held mint-and-treasury-authority over the EZ token contract. The pre-event risk-assessment surface existed but defender audit-attention was not commonly applied to authority-graph review at that period.
At-event (rapid mint-event detection). The EZ-supply-mint-event was detectable via standard token-supply monitoring; the team identified the compromise within hours and deployed emergency-pause. The detection-to-pause latency was approximately 2-4 hours per public timeline.
Post-event (operator-funded recovery). EasyFi V2 relaunch with operator-funded compensation framework is the recovery pattern for cases where the attacker successfully extracts and dumps before operator-side emergency-pause can be deployed; pairs with Holograph June 2024 (examples/2024-06-holograph.md) and DeltaPrime September 2024 (examples/2024-09-deltaprime.md) operator-funded-recovery patterns.

What this example tells contributors writing future Technique pages

Single-EOA admin authority is the foundational T11.002 sub-pattern. Future T11.002 contributions should explicitly enumerate single-EOA-admin-authority as a discrete pre-incident architectural anti-pattern, distinct from multisig-with-insufficient-operator-separation (Ronin Bridge) and HSM/MPC-with-UI-compromise (Bybit Feb 2025) sub-patterns.
Authority-graph audit is a discrete pre-deployment check class. OAK-M05 authority-graph enumeration and OAK-M22 rotate-on-disclosure discipline are the load-bearing mitigations; the EasyFi case is a canonical reference for the proposition that authority-graph review at protocol-launch time is itself an audit class composing with general-purpose pre-deployment audit.
Polygon-team coordination is a chain-validator-coordinated emergency-response surface. EasyFi's partial recovery via Polygon team coordination is structurally analogous to the Cetus Sui validator-coordinated freeze (May 2025) and the Thala Aptos validator-coordinated freeze (Nov 2024) but at a substantially-earlier point in the chain-validator-coordination evolution. Future T11.002 contributions should distinguish chain-level-coordinated emergency response from protocol-level emergency-pause as separate mitigation classes.

Public references

EasyFi operator-side incident statement (April 2021) — [easyfipostmortem2021].
Anshul Dhir personal statement on the compromise — [dhirstatement2021].
PeckShield on-chain trace — [peckshieldeasyfi2021].
BlockSec function-level walkthrough — [blocksec_easyfi2021].
SlowMist incident analysis — [slowmisteasyfi2021].
Rekt News public-facing summary — [rekteasyfi2021].

Citations

[easyfipostmortem2021] — EasyFi operator-side post-mortem and EasyFi V2 compensation-framework announcement.
[dhirstatement2021] — Anshul Dhir personal statement on the MetaMask EOA compromise.
[peckshieldeasyfi2021] — PeckShield on-chain trace.
[blocksec_easyfi2021] — BlockSec function-level walkthrough.
[slowmisteasyfi2021] — SlowMist incident analysis.
[rekteasyfi2021] — Rekt News public-facing summary.

Discussion

EasyFi April 2021 is the foundational single-EOA-admin-authority compromise worked example in the OAK reference period and pairs with Spartan Protocol May 2 (LP-share-virtual-price subclass of T9.001) and PancakeBunny May 19 (yield-aggregator-mint-pricing subclass of T9.001) to give the April-May 2021 BSC-and-Polygon DeFi exploit cohort a three-case structural articulation across three distinct attack-class subclasses. Defenders writing operator-cohort-attribution for early-stage-chain rollouts should treat the cohort as a recurring framework-level pattern: a new chain attracts protocols ported with minimal authority-graph-and-fork-substrate-vulnerability audit and produces a high-frequency exploit cohort in the first ~12 months of substantial TVL.

The single-EOA-admin-authority anti-pattern recurs across many subsequent cases (Ankr Dec 2022, Holograph Jun 2024, DeltaPrime Sep 2024, UPCX Apr 2025); EasyFi is the canonical 2021 anchor. Future T11.002 contributions should treat single-EOA-admin-authority as a foundational sub-pattern within the broader admin-key-compromise class, with the appropriate mitigation being OAK-M37 HSM/MPC custody for institutional-and-protocol-treasury contexts and OAK-M22 rotate-on-disclosure + OAK-M05 authority-graph enumeration as universally-applicable composing mitigations.

The pseudonymous-unattributed framing reflects per-incident attribution at the time. Industry-cohort-graph analysis at v0.1 cutoff did not produce an inferred-strong attribution; future industry forensic-cluster-attribution updates may produce stronger attribution.