Submitted by 0x52
https://github.com/code-423n4/2022-11-paraspace/blob/c6820a279c64a299a783955749fdc977de8f0449/paraspace-core/contracts/protocol/libraries/logic/SupplyLogic.sol#L462-L512
Adversary can DOS user and make them pay more gas by sending them collateral.
The above lines are executed when a user transfer collateral to another user. If the sending user currently has the collateral enabled and the receiving user doesnt have a balance already, the collateral will automatically be enabled for the receiver. Since the collateral is enabled, it will now be factored into the health check calculation. This increases gas for the receiver every time the user does anything that requires a health check (which ironically includes turning off a collateral). If enough different kinds of collateral are added to the platform it may even be enough gas to DOS the users.
Dont automatically enable the collateral for the receiver.
