Praise be to Allah the Lord of the Worlds.
Computer programs created and issued by companies are intellectual property of theirs. According to customary practices, intellectual property is among the protected rights and this is approved by modern Islamic jurisprudence. Those programs cost a great deal of effort and money and people working on them are trusted. Therefore, it isn`t permissible that they disclose, copy or transgress against them, because doing so harms the business of such company and doesn`t agree with what is dictated by the public interest. It was narrated from Ibn 'Abbas that the Messenger of Allah (PBUH) said: “There should be neither harming nor reciprocating harm.” {Ibn Maja}.
Nevertheless, if you want to work in the same field, then you must quit from that company before you start your own business and you must avoid using the secret of that trade, which you were trusted to uncover, in order to be cleared from liability before Allah the Almighty.
An-Nawwas bin Sam'an (RAA) narrated: "I asked the Messenger of Allah (PBUH) about virtue and sin and he replied: “The essence of virtue is (manifested in) good morals (Akhlaq) whereas sinful conduct is that which turns in your heart (making you feel uncomfortable) and you dislike that it would be disclosed to other people.” {Related by Muslim}. And Allah the Almighty Knows Best.