Safe Dollar Hack

TOTAL LOST $95K
Low Other polygon

Summarize with AI

ChatGPT Perplexity Claude Grok
Affected Chain polygon Incident surface
Recovered - No recovery reported
All-Time Rank #1542 By amount stolen
Protocol Type Exploit/Other Target category

Incident Overview

The attacker's address:

https://polygonscan.com/address/0x8a0a1eb0…907c6c

The attack transaction:

https://polygonscan.com/tx/0x76c722c7…66b210

The re-entrance attack on the Token Locker smart contract was performed, Safe Dollar share tokens were affected.

The contract itself does not have an issue with standard ERC20, but since the PLX token is ERC777 standard, there will be tokenReceived() callback event every time method transfer() triggered. The attacking smart contract deployed by the hacker has included the unlockAll() trigger repeatedly (40 times) in the event, so he was able to unlock more than the amount he locked in before.

The attacker withdrew 9,959.26 SDS, then sold for 95,392 USDC after bridging all to Ethereum.

Incident Report

Protocol / Project Safe Dollar
Date of Incident
Affected Chain(s) polygon
Attack Technique Other
Classification Stablecoin
Primary Source View Post-Mortem #1 View Post-Mortem #2

Protocol Information

Protocol Type Exploit/Other
Affected Token SDS
Official Website www.safedollar.fi/
Protocol Twitter/X @safedollarfi

Market Context at Time of Hack

Token Categories
Store Of Value Stablecoin Asset-Backed Stablecoin USD Stablecoin Fiat Stablecoin Binance Ecosystem Binance Listing
Protocol Links
GitHub

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 polygon smart contracts and deploy a custom exploit contract
Protocol Analysis Identification of the exploitable vulnerability in Safe Dollar's contract logic - root cause: stablecoin
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 Safe Dollar, these are the critical security checks that could have prevented this incident (June 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

Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.

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Sources & References

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