Is it Islamically permissible to work at the International Investment Bank as a fraud monitor, and is the received salary lawful or unlawful, knowing that the work is not out of necessity?

Working in a bank is permissible if it deals with transactions that conform to Islamic Sharia and is free from usurious dealings. However, if the bank deals with usury (riba), it is not permissible to work there in any position, even as a fraud monitor, because that falls under the category of cooperating in sin and aggression. Allah Almighty said: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." The prohibition of usury is more severe than the prohibition of fraud. Allah has warned those who engage in it with war, as He said: "O you who have believed, fear Allah and give up what remains [due to you] of usury, if you should be believers. And if you do not, then be informed of a war [against you] from Allah and His Messenger." Therefore, it is not permissible to work in a usurious bank.