\documentclass[dvipsnames,14pt,t]{beamer}
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%%\usepackage[T1]{fontenc}
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	basicstyle=\consolas,
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% beamer stuff 
\renewcommand{\slidecaption}{APP 03, King's College London, 8 October 2013}


\begin{document}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}<1>[t]
\frametitle{%
  \begin{tabular}{@ {}c@ {}}
  \\
  \LARGE Access Control and \\[-3mm] 
  \LARGE Privacy Policies (3)\\[-6mm] 
  \end{tabular}}\bigskip\bigskip\bigskip

  %\begin{center}
  %\includegraphics[scale=1.3]{pics/barrier.jpg}
  %\end{center}

\normalsize
  \begin{center}
  \begin{tabular}{ll}
  Email:  & christian.urban at kcl.ac.uk\\
  Office: & S1.27 (1st floor Strand Building)\\
  Slides: & KEATS (also home work is there)
  \end{tabular}
  \end{center}


\end{frame}}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\begin{center}
\begin{tabular}[t]{c}
\includegraphics[scale=1.2]{pics/barrier.jpg}\\
first lecture
\end{tabular}\;\;\;
\onslide<2>{
\begin{tabular}[t]{c}
\includegraphics[scale=0.32]{pics/trainwreck.jpg}\\
today
\end{tabular}
}
\end{center}

  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Network Applications:\\[-1mm] Privilege Separation\end{tabular}}


\begin{center}
  \begin{tikzpicture}[scale=1]
  
  \draw[line width=1mm] (-.3, 0) rectangle (1.5,2);
  \draw (4.7,1) node {Internet};
  \draw (-2.7,1.7) node {\footnotesize Application};
  \draw (0.6,1.7) node {\footnotesize Interface};
  \draw (0.6,-0.4) node {\footnotesize \begin{tabular}{c}unprivileged\\[-1mm] process\end{tabular}};
  \draw (-2.7,-0.4) node {\footnotesize \begin{tabular}{c}privileged\\[-1mm] process\end{tabular}};
  
  \draw[line width=1mm] (-1.8, 0) rectangle (-3.6,2);

  \draw[white] (1.7,1) node (X) {};
  \draw[white] (3.7,1) node (Y) {};
  \draw[red, <->, line width = 2mm] (X) -- (Y);
 
  \draw[red, <->, line width = 1mm] (-0.6,1) -- (-1.6,1);
  \end{tikzpicture}
\end{center}

\begin{itemize}
\item the idea is make the attack surface smaller and 
mitigate the consequences of an attack
\end{itemize}


\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Access Control in Unix}

\begin{itemize}
\item access control provided by the OS
\item authenticate principals (login)
\item mediate access to files, ports, processes according to \alert{roles} (user ids)\\
\item roles get attached with privileges\bigskip\\%
\hspace{8mm}
\begin{tikzpicture}
\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm] 
{\begin{minipage}{8cm}
\alert{The principle of least privilege:}\\
programs should only have as much privilege as they need 
\end{minipage}};
\end{tikzpicture}
\end{itemize}

\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     


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\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{@ {}c@ {}}A ``Cron''-Attack\end{tabular}}

\begin{enumerate}
\item attacker \textcolor{gray}{(creates a fake passwd file)}\\ 
\texttt{mkdir /tmp/a; cat > /tmp/a/passwd}\medskip
\item root \textcolor{gray}{(does the daily cleaning)}\\
\texttt{rm /tmp/*/*}\medskip\\
\hspace{2cm}\textcolor{gray}{\small records that \texttt{/tmp/a/passwd}}\\ 
\hspace{2cm}\textcolor{gray}{\small should be deleted, but does not do it yet}\medskip\\

\item attacker \textcolor{gray}{(meanwhile deletes the fake passwd file, and establishes a link to 
the real passwd file)}\\
\texttt{rm /tmp/a/passwd; rmdir /tmp/a;}\\\texttt{ln -s /etc /tmp/a}\\
\item root now deletes  the real passwd file
\end{enumerate}

\only<2>{
\begin{textblock}{11}(2,5)
\begin{tikzpicture}
\draw (0,0) node[inner sep=2mm,fill=cream, ultra thick, draw=red, rounded corners=2mm] 
{\normalsize\color{darkgray}
\begin{minipage}{9cm}\raggedright
To prevent this kind of attack, you need additional
policies (don't do such operations as root).
\end{minipage}};
\end{tikzpicture}
\end{textblock}}

\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{@ {}c@ {}}Smash the Stack for Fun \ldots\end{tabular}}

\begin{itemize}
\item ``smashing the stack attacks'' or\\ ``buffer overflow attacks''\medskip
\item one of the most popular attacks\\ ($>$ 50\% of security incidents reported at CERT are related to buffer overflows)
\begin{flushright}\small
\textcolor{gray}{\url{http://www.kb.cert.org/vuls}}
\end{flushright}
\medskip
\item made popular in an article by Elias Levy\\ (also known as Aleph One):\\
\begin{center}
{\bf ``Smashing The Stack For Fun and Profit''}
\end{center}\medskip

\begin{flushright}
\small\textcolor{gray}{Issue 49, Article 14}
\end{flushright} 
 
\end{itemize}


\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{A Float Printed ``Twice''}

{\lstset{language=Java}
\footnotesize
\lstinputlisting{../progs/C1.c}}

\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}The Problem\end{tabular}}

\begin{itemize}
\item The basic problem is that library routines in C look as follows:

\begin{center}
{\lstset{language=Java}
\footnotesize
\lstinputlisting{../progs/app5.c}}
\end{center}

\item the resulting problems are often remotely exploitable 
\item can be used to circumvents all access control\\
(for grooming botnets for further attacks)
\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Variants\end{tabular}}

There are many variants:

\begin{itemize}
\item return-to-lib-C attacks
\item heap-smashing attacks\\
\textcolor{gray}{\small(Slammer Worm in 2003 infected 90\% of vulnerable systems within 10 minutes)}\bigskip

\item ``zero-days-attacks'' (new unknown vulnerability)
\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\begin{center}
\only<1>{\includegraphics[scale=0.9]{pics/stack1}\;\;}
\only<2>{\includegraphics[scale=0.9]{pics/stack2}\;\;}
\only<3>{\includegraphics[scale=0.9]{pics/stack3}\;\;}
\end{center}
  
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

{\lstset{language=Java}\fontsize{8}{10}\selectfont%
\texttt{\lstinputlisting{../progs/C2.c}}}

  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\small
A programmer might be careful, but still introduce vulnerabilities:\bigskip

{\lstset{language=Java}\fontsize{8}{10}\selectfont%
\texttt{\lstinputlisting{../progs/C2a.c}}}

  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Payloads\end{tabular}}

\begin{itemize}
\item the idea is you store some code to the buffer
\item you then override the return address to execute this payload\medskip
\item normally you start a root-shell\pause
\item difficulty is to guess the right place where to ``jump''
\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Payloads (2)\end{tabular}}

\begin{itemize}
\item another difficulty is that the code is not allowed to contain \texttt{$\backslash$x00}:

\begin{center}
\texttt{xorl   \%eax, \%eax}
\end{center}
\end{itemize}\bigskip\bigskip
  
{\lstset{language=Java}\small
\texttt{\lstinputlisting{../progs/app5.c}}}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Format String Vulnerability\end{tabular}}

\small
\texttt{string} is nowhere used:\bigskip

{\lstset{language=Java}\fontsize{8}{10}\selectfont%
\texttt{\lstinputlisting{../progs/C4.c}}}\bigskip

this vulnerability can be used to read out the stack
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Protections against\\ BO Attacks\end{tabular}}

\begin{itemize}
\item use safe library functions
\item ensure stack data is not executable (can be defeated)
\item address space randomisation (makes one-size-fits-all more difficult)
\item choice of programming language (one of the selling points of Java)

\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Security Goals\end{tabular}}

\begin{itemize}
\item Prevent common vulnerabilities from occurring (e.g. buffer overflows)\pause
\item Recover from attacks (traceability and auditing of security-relevant actions)\pause
\item Monitoring (detect attacks)\pause
\item Privacy, confidentiality, anonymity (to protect secrets)\pause
\item Authenticity (needed for access control)\pause
\item Integrity (prevent unwanted modification or tampering)\pause
\item Availability and reliability (reduce the risk of DoS attacks)
\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}Homework\end{tabular}}

\begin{itemize}
\item Assume format string attacks allow you to read out the stack. What can you do
	with this information?\bigskip

\item Assume you can crash a program remotely. Why is this a problem?
\end{itemize}
  
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   


\end{document}

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