In some implementations, an authentication system may receive, from a client device, a credential associated with a user account and a request to access a resource. The authentication system may transmit, to the client device, a request for an image of a customized physical security token associated with the user account. The authentication system may receive, from the client device, a first image. The authentication system may compare the first image with a representation of a second image of the customized physical security token associated with the user account. The authentication system may grant or denying access to the resource based on comparing the first image with the representation of the second image.