yocto-attach.md

Lack of two-factor authentication

Configuration

• detector id: yocto-attach
• severity: medium

Description

Privileged functions should check whether one yocto NEAR is attached. This will enable the 2FA in the NEAR wallet for security concerns.

This can be implemented in the contract by adding assert_one_yocto, which is recommended for all privileged functions.

Note: It's hard to locate all the privileged functions without semantic information. Currently, Rustle considers all functions with predecessor_account_id involved in comparisons as privileged ones.

Sample code

pub(crate) fn assert_owner(&self) {
    assert_eq!(
        env::predecessor_account_id(),
        self.owner_id,
        "{}", ERR100_NOT_ALLOWED
    );
}

// https://github.com/ref-finance/ref-contracts/blob/536a60c842e018a535b478c874c747bde82390dd/ref-exchange/src/owner.rs#L16
#[payable]
pub fn set_owner(&mut self, owner_id: ValidAccountId) {
    assert_one_yocto();
    self.assert_owner();
    self.owner_id = owner_id.as_ref().clone();
}

In this sample, set_owner is a privileged function and should only be invoked by the contract owner. Function assert_owner ensures the privilege by checking its predecessor_account_id. This function should have a 2FA for security concerns, and this can be implemented by adding an assert_one_yocto invocation in the function.