1. A computer-implemented method comprising: receiving, by one or more processors, an access request from a client computer for access to a protected resource stored on a target server; forwarding, by the one or more processors, the access request to the target server; receiving, by the one or more processors, an access response from the target server, wherein the access response is a credential form including credential fields required to access the protected resource; injecting, by the one or more processors, a credential field tag into each required credential field; sending, by the one or more processors, the tagged credential form to the client computer; receiving, by the one or more processors, a tagged credential form from the client computer including tagged credentials in the required credential fields with the credential field tags, wherein the tagged credentials are auto-submitted by the client computer; replacing, by the one or more processors, the tagged credentials with target credentials mapped by the credential field tags, wherein the target credentials are stored in a protected data store; sending, by the one or more processors, the target credentials to the target server; updating, by the one or more processors, the target credentials and storing the updated target credentials in a protected data store without client intervention; determining, by the one or more processors, the target credentials are invalid; replacing, by the one or more processors, the invalid target credentials with the updated target credentials and submitting the updated target credentials to the target server, in response to the target credentials being invalid; and allowing, by the one or more processors, the client computer to access the protected resource, in response to the target server validating the target credentials.