It is not permissible to work at any interest-based bank. Usurious interest is not only prohibited in itself but any act or work that helps on procuring, giving or even witnessing such a practice is prohibited.

The Messenger of Allah (peace be upon him) cursed the one who consumes riba, the one who pays it, the one who witnesses it and the one who writes it down; the woman who does tattoos and the woman who has that done; and forbade wailing (in mourning), but he did not say that its doer is cursed. (Al-Nasa’i)

Allah Almighty knows best.