Q1899. What is the ruling in the matter of working in banks that deal with ribā, especially if there are no other jobs to do?
A: If the work in the bank is, in any way, related to ribā-based transactions, it is not permissible. However, the claim that no other ḥalāl employment by which to earn a living is available is not a valid reason to dabble in ḥarām business.
http://www.leader.ir/en/book/32/Practical-Laws-of-Islam