--- a/handouts/ho03.tex	Wed Oct 22 23:38:02 2014 +0100
+++ b/handouts/ho03.tex	Thu Oct 23 00:45:21 2014 +0100
@@ -1,35 +1,14 @@
 \documentclass{article}
 \usepackage{../style}
 \usepackage{../langs}
+\usepackage{../graphics}
+\usepackage{../data}
 \usetikzlibrary{patterns,decorations.pathreplacing}
 
 \begin{document}
 
 \section*{Handout 3 (Buffer Overflow Attacks)}
 
-\begin{center}
-\begin{tikzpicture}
-\begin{axis}[xlabel={\pcode{a}s},ylabel={time in secs},
-    enlargelimits=false,
-    xtick={0,5,...,30},
-    xmax=30,
-    ymax=35,
-    ytick={0,5,...,30},
-    scaled ticks=false,
-    axis lines=left,
-    width=5cm,
-    height=5cm, 
-    legend entries={Python,Ruby},  
-    legend pos=north west,
-    legend cell align=left]
-\addplot[blue,mark=*, mark options={fill=white}] 
-  table {re-python.data};
-\addplot[brown,mark=pentagon*, mark options={fill=white}] 
-  table {re-ruby.data};  
-\end{axis}
-\end{tikzpicture}
-\end{center}
-
 By far the most popular attack method on computers are buffer
 overflow attacks or variations thereof. The first Internet
 worm (Morris) exploited exactly such an attack. The popularity
@@ -37,7 +16,32 @@
 prevent them effectively. But these kind of attacks are still
 very relevant even today since there are many legacy systems
 out there and also many modern embedded systems often do not
-take any precautions to prevent such attacks.
+take any precautions to prevent such attacks. The plot below shows
+the percentage of buffer overflow attacks w.r.t.~all attacks.
+The data is taken from the US National Vulnerability Database.
+
+\begin{center}
+\begin{tikzpicture}
+\begin{axis}[
+    xlabel={year},
+    ylabel={\% of total attacks},
+    enlargelimits=false,
+    xtick={1997,1999,...,2014},
+    xmax=2015,
+    ymax=20,
+    ytick={0,2,...,20},
+    scaled ticks=false,
+    axis lines=left,
+    width=9cm,
+    height=5cm,
+    ybar,
+    x tick label style={font=\footnotesize}]
+\addplot
+  table [x=Year,y=Percentage] {bufferoverflows.data};
+\end{axis}
+\end{tikzpicture}
+\end{center}
+
 
 To understand how buffer overflow attacks work, we have to have
 a look at how computers work ``under the hood'' (on the