A computer implemented method to prevent attacks against authorization systems, wherein a second server, in connection with a computing device of a user, via a second dedicated program installed in said computing device, is used to manage a status of the accounts the user has in a first server and a status of the operations defined for a particular account, said account status and said operation status being set, whenever the user wants, as valid or as invalid by the user via the second dedicated program and stored in a memory of the second server, and said account status and said operation status being set by the user once a pairing process with the second server being completed, said pairing process ensuring privacy to the user, the method comprising: - receiving, by said first server, from the user using a first dedicated program including a browser, a request to be logged into a service of said first server, said request including the provision of identification information validating the identity of the user in the first server; - once user existence has been validated by the first server, receiving, by said second server, from the first server, a request about a status regarding an account of the user in the first server; - in response to receiving the request, initializing a first credential exchange between said first and said second server in order to provide mutual authentication, the first credential exchange being performed via an authentication procedure based on certificates' exchange; - verifying, by said second server, said account status; - sending, by said second server, said account status to said first server; and - using, by said first server, said received account status for: ∘ authorizing said service logging request if said account status is set as valid, or ∘ rejecting said service logging request if said account status is set as invalid, wherein in response to said request to be logged into a service of said first server being authorized, a further request is done by the user via the browser to perform an operation related to said account in the first server, the method further comprising: - determining, by the first server, what entry in a scheme of an hierarchy defined by the account corresponds with said requested operation; - requesting, by the first server, to the second server, the operation status defined by the user over said entry; - initializing a second credential exchange between the first server and the second server; - evaluating, by the second server, a scheme entry status from a root of said hierarchy scheme to said entry; - sending, by the second server an evaluation result to the first server; and - making a decision, by the first server, by at least using said received result for allowing or blocking said requested operation. - receiving, by said first server, from the user using a first dedicated program including a browser, a request to be logged into a service of said first server, said request including the provision of identification information validating the identity of the user in the first server; - once user existence has been validated by the first server, receiving, by said second server, from the first server, a request about a status regarding an account of the user in the first server; - in response to receiving the request, initializing a first credential exchange between said first and said second server in order to provide mutual authentication, the first credential exchange being performed via an authentication procedure based on certificates' exchange; - verifying, by said second server, said account status; - sending, by said second server, said account status to said first server; and - using, by said first server, said received account status for: ∘ authorizing said service logging request if said account status is set as valid, or ∘ rejecting said service logging request if said account status is set as invalid, ∘ authorizing said service logging request if said account status is set as valid, or ∘ rejecting said service logging request if said account status is set as invalid, - determining, by the first server, what entry in a scheme of an hierarchy defined by the account corresponds with said requested operation; - requesting, by the first server, to the second server, the operation status defined by the user over said entry; - initializing a second credential exchange between the first server and the second server; - evaluating, by the second server, a scheme entry status from a root of said hierarchy scheme to said entry; - sending, by the second server an evaluation result to the first server; and - making a decision, by the first server, by at least using said received result for allowing or blocking said requested operation.