DittoETH

Summary

User account is skimmed off shares on closing of bid.

Vulnerability Details

uint88 shares = eth * (timeTillMatch / 1 days);

POC

User bid is matched at Epoch 1695556800

The first method is the method as used in the protocol, and the second method is as what is meant to be, then we calculate the difference from the first and second to see how much the user would have gotten if calculated properly.

Method one

timeTillMatch / 1 days

1695556800 / 86400

19624 * 1e18 = 1.9624e+22

Method two

timeTillMatch * 1e18

1695556800 * 1e18

1.6955568e+27 / 1 days = 1.96245e+22

Difference

Method two - Method one

1.96245e+22 - 1.9624e+22 = 500000000000917500;

Difference scaled down

500000000000917500 / 1e18

diff = 0.5000000000009175

Impact

User shares is wrongly reduced at closing of match.

Tools Used

Manual

Recommendations

uint shares = (timeTillMatch * eth) / 1 days ;