Systems and methods for securely accessing a legacy system are disclosed herein. In an embodiment, a method for securely accessing a legacy system via an enterprise system includes requesting issuance of a security token by an STS server of a security token service, causing, by an enterprise server of an enterprise system, association of a first user account with the security token upon reception of the security token, communicating the security token to an access server of a legacy access provider for authentication of the security token, enabling creation of a second user account after the legacy access provider authenticates the security token, accessing a legacy server of a legacy system via the first user account and the second user account, and causing at least the second user account to be deleted after a single use of the legacy system.