All of these function have one thing in common. They transfer loan token ( USDC ) to the lender.
Consider a scenario where a lender's address that is about to be blacklisted gives a loan to an innocent borrower.
Since lender got blacklisted, a lender cannot repay their loan , nor they can consider refinance or even auction is lender decides to call the loan. All of this is because transfer of usdc cannot happen on a blacklisted address.
Borrowers tokens are stuck he cannot get back no matter what.
Internal pre-conditions
No response
External pre-conditions
Lender's address about to be blacklisted
Attack Path
Bob ( lender ) knows his address is about to blacklisted.
He quickly uses matchProposal or acceptBorrowRequest for an innocent borrower, Alice.
Bob's address becomes blacklisted.
Alice can't repay , refinance or auction her loan since safeTransferFrom on Bob's address will not work.
Impact
Borrower's CTF tokens are stuck in the contract that he cannot get back or roll over.
PoC
No response
Mitigation
Not sure about mitigation but we can proactively check in all the 3 functions is lender has become blacklisted and then create extra logic to handle loan after that.
Bright Saffron Urchin
Medium
Borrowers loan can get stuck if lender becomes usdc blacklisted after giving loan.
Summary
If a lender that is about to be blacklisted gives a loan to an innocent borrower then borrower can't use
repay(),refinance()or everauction().Root Cause
Consider these 3 functions.
repay()
refinance()
auction()
All of these function have one thing in common. They transfer loan token ( USDC ) to the lender.
Consider a scenario where a lender's address that is about to be blacklisted gives a loan to an innocent borrower. Since lender got blacklisted, a lender cannot repay their loan , nor they can consider refinance or even auction is lender decides to call the loan. All of this is because transfer of usdc cannot happen on a blacklisted address.
Borrowers tokens are stuck he cannot get back no matter what.
Internal pre-conditions
No response
External pre-conditions
Lender's address about to be blacklisted
Attack Path
matchProposaloracceptBorrowRequestfor an innocent borrower, Alice.repay,refinanceorauctionher loan since safeTransferFrom on Bob's address will not work.Impact
Borrower's CTF tokens are stuck in the contract that he cannot get back or roll over.
PoC
No response
Mitigation
Not sure about mitigation but we can proactively check in all the 3 functions is lender has become blacklisted and then create extra logic to handle loan after that.