PolkaTrain Hack

TOTAL LOST $3.0M
Medium Other

Summarize with AI

ChatGPT Perplexity Claude Grok
Affected Chain 2021 Incident surface
Recovered - No recovery reported
All-Time Rank #548 By amount stolen
Protocol Type Exploit/Other Target category

Incident Overview

Around 3:00 a.m. UCT + 8 on April 5, 2021, the smart contract of Polkatrain was attacked by hackers during the LBP auction, 57000 DOT were stolen in the contract and turned away.

The LBP contract has a swap function and a rebate mechanism. When users buy PLOT tokens through the swap function, they get a certain amount of rebates, and the rebates will be It is sent to the user by calling transferFrom in the _update function in the contract. Since the _update function does not set the maximum amount of rebates in a pool, nor does it determine whether the total rebates are used up when rebates, malicious arbitrageurs can continue to call the swap function to exchange tokens to get the contract.

Incident Report

Protocol / Project PolkaTrain
Date of Incident
Attack Technique Other
Classification Other
Primary Source View Post-Mortem #1 View Post-Mortem #2

Protocol Information

Protocol Type Exploit/Other
Official Website www.polkatrain.com/
Protocol Twitter/X @polkatrain
Team Anonymous
Source Code Unverified

Market Context at Time of Hack

Token Categories
Art Marketplace Collectibles & NFTs Ethereum Ecosystem Poolz Finance Portfolio PolkaFoundry Red Kite OKX Ventures Portfolio
Protocol Links

What the Attacker Needed to Succeed

Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.

Technical Knowledge Deep understanding of other and Solidity and EVM internals
Capital Required Seed capital to cover gas and initial position setup
On-Chain Access Ability to interact with smart contracts and deploy a custom exploit contract
Protocol Analysis Identification of the exploitable vulnerability in PolkaTrain's contract logic - root cause: other
Execution Speed Precise transaction ordering and timing to exploit the vulnerability within a single atomic block
Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Likely — with a thorough Other audit checklist and test coverage

If you're auditing a protocol with similar architecture to PolkaTrain, these are the critical security checks that could have prevented this incident (April 2021).

  • Verify all logic paths related to Other are guarded by proper access controls and input validation
  • Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs

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Sources & References

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