338 

   339 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   340 \tikzset{alt/.code args={<#1>#2#3#4}{%

   341   \alt<#1>{\pgfkeysalso{#2}}{\pgfkeysalso{#3}} % \pgfkeysalso doesn't change the path

   342 }}

   343 

   344 \begin{frame}[t]

   345 \frametitle{Buffer Overflow Attacks}

   346 

   347 \begin{itemize}

   348 \item the problem arises from the way C/C++ organises its function calls\\[-8mm]\mbox{}

   349 \end{itemize}

   350 

   351 \begin{center}

   352 \begin{tikzpicture}[scale=1]

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   354 %\draw[black!10,thick,step=10mm] (0,0) grid (9,4);

   355 

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   359 \draw[line width=1mm, alt=<3->{fill=yellow}{fill=blue}] (0,2.0) rectangle (1,2.5);

   360 \draw[line width=1mm, alt=<6->{fill=red}{fill=blue}] (0,1.0) rectangle (1,2.0);

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   363 \draw[line width=1mm] (1,0) -- (1,4);

   364 

   365 \node at (3.5,3.5) {\small\begin{tabular}{l}fact(n)\end{tabular}};

   366 \draw[line width=1mm, alt=<{4-5,8}>{fill=red}{fill=blue}] (3,1.0) rectangle (4,3.0);

   367 

   368 \onslide<3-4>{\draw[->, line width=1mm,red] (1,2.3) to node [above,sloped,midway] {n=4} (3,3);}

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   370 

   371 \onslide<7-8>{\draw[->, line width=1mm,red] (1,0.8) to node [above,sloped,midway] {n=3} (3,3);}

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   373 

   374 

   375 \node at (7.75,3.9) {\small\begin{tabular}{l}stack\end{tabular}};

   376 \draw[line width=1mm] (7,3.5) -- (7,0.5) -- (8.5,0.5) -- (8.5,3.5);

   377 

   378 \onslide<3,4,7,8>{

   379 \node at (7.75, 1.4) {ret};

   380 \draw[line width=1mm] (7,1.1) -- (8.5,1.1);

   381 \node at (7.75, 2.0) {sp};

   382 \draw[line width=1mm] (7,2.3) -- (8.5,2.3);

   383 }

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   386 \draw[line width=1mm] (7,1.7) -- (8.5,1.7);

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   390 \draw[line width=1mm] (7,1.7) -- (8.5,1.7);

   391 }

   392 

   393 

   394 \end{tikzpicture}

   395 \end{center}

   396 

   397 \end{frame}

   398 

   399 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

   400 \begin{frame}[t]

   401 

   402 \begin{center}

   403 \begin{tikzpicture}[scale=1]

   404 %\draw[black!10,step=2mm] (0,0) grid (9,4);

   405 %\draw[black!10,thick,step=10mm] (0,0) grid (9,4);

   406 

   407 \node at (0.5,4.5) {\small\begin{tabular}{l}main\\[-2mm] prog.\end{tabular}};

   408 \draw[line width=0mm, white, alt=<2->{fill=red}{fill=blue}] (0,2.5) rectangle (1,3.8);

   409 \draw[line width=1mm, white, fill=blue] (0,1.0) rectangle (1,2.0);

   410 \draw[line width=1mm, alt=<3->{fill=yellow}{fill=blue}] (0,2.0) rectangle (1,2.5);

   411 \draw[line width=1mm] (0,0) -- (0,4);

   412 \draw[line width=1mm] (1,0) -- (1,4);

   413 

   414 \node at (3.5,3.5) {\small\begin{tabular}{l}fact(n)\end{tabular}};

   415 \draw[line width=0mm, alt=<{4-}>{red, fill=red}{blue, fill=blue}] (3,2.8) rectangle (4,3.0);

   416 \draw[line width=0mm, alt=<{5-}>{red, fill=red}{blue, fill=blue}] (3,2.8) rectangle (4,2.0);

   417 \draw[line width=0mm, alt=<{7-}>{red, fill=red}{blue, fill=blue}] (3,2.0) rectangle (4,1.0);

   418 \draw[line width=1mm] (3,1.0) rectangle (4,3.0);

   419 

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   421 \onslide<5->{\draw[<-, line width=2mm,red] (4,2) to node [above,sloped,midway] 

   422 {\begin{tabular}{l}user\\[-1mm] input\end{tabular}} (6,2);}

   423 \onslide<8->{\draw[<-, line width=1mm,red] (1,-2) to (3,1);}

   424 

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   426 \draw[line width=1mm] (7,3.5) -- (7,-0.1) -- (8.5,-0.1) -- (8.5,3.5);

   427 

   428 \onslide<3->{

   429 \node at (7.75, 0.2) {4};

   430 \draw[line width=1mm,alt=<6->{fill=red}{fill=white}] (7,0.5) rectangle (8.5,1.1);

   431 \node at (7.75, 0.8) {\alt<6->{@a\#}{ret}};

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   434 }

   435 

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   440 

   441 \end{tikzpicture}

   442 \end{center}

   443 

   444 \end{frame}

   445 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

   446