\begin{tikzpicture}

    \def \h{4}

    %Donnée utilisateur
    \node[rectangle,draw=red] (s) at (2*\h,0) {Sensitive attribute};

    %Pipeline
    \node[rectangle,draw=blue] (inf) at (0,0) {Classification};

    %Attaque
    \node[rectangle,draw=blue] (att) at (\h,0) {Attack};

    \draw[->,color=blue] (inf) to (att);
    \draw[->,color=red] (att) to (s);

\end{tikzpicture}