hws/hw03.tex
author Christian Urban <christian dot urban at kcl dot ac dot uk>
Mon, 05 Oct 2015 12:25:47 +0100
changeset 392 4dff36e2bbc6
parent 389 9019f84ef99c
child 465 76f9457b8f51
permissions -rw-r--r--
updated
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
33
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
     1
\documentclass{article}
389
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
     2
\usepackage{../style}
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
     3
33
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
     4
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
     5
\begin{document}
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
     6
39
Christian Urban <urbanc@in.tum.de>
parents: 38
diff changeset
     7
\section*{Homework 3}
33
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
     8
389
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
     9
\HEADER
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
    10
33
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    11
\begin{enumerate}
239
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    12
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    13
\item How does a buffer-overflow attack work? (Hint: What happens on
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    14
  the stack.)
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    15
276
d7109c6e721d updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 257
diff changeset
    16
\item Why is it crucial for a buffer overflow attack that the stack
239
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    17
  grows from higher addresses to lower ones?
34
Christian Urban <urbanc@in.tum.de>
parents: 33
diff changeset
    18
257
9bc912fcedb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 239
diff changeset
    19
\item If the attacker uses a buffer overflow attack in order to
9bc912fcedb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 239
diff changeset
    20
inject code, why can this code not contain any zero bytes?
9bc912fcedb6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 239
diff changeset
    21
239
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    22
\item How does a stack canary help with preventing a buffer-overflow
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    23
  attack?
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    24
389
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
    25
\item Why does randomising the addresses from where programs 
9019f84ef99c updated hws
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 276
diff changeset
    26
  are run help defending against buffer overflow attacks?
239
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    27
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    28
\item Assume format string attacks allow you to read out the
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    29
  stack. What can you do with this information? (Hint: Consider what
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    30
  is stored in the stack.)
34
Christian Urban <urbanc@in.tum.de>
parents: 33
diff changeset
    31
110
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 97
diff changeset
    32
\item Assume you can crash a program remotely. Why is this a problem?
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 97
diff changeset
    33
239
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    34
\item How can the choice of a programming language help with buffer
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    35
  overflow attacks?  (Hint: Why are C-programs prone to such attacks,
0db764174afb updated home works
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 144
diff changeset
    36
  but not Java programs.)
392
4dff36e2bbc6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 389
diff changeset
    37
  
4dff36e2bbc6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 389
diff changeset
    38
\item When filling the buffer that is attacked with a
4dff36e2bbc6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 389
diff changeset
    39
payload (starting a shell), what is the purpose of 
4dff36e2bbc6 updated
Christian Urban <christian dot urban at kcl dot ac dot uk>
parents: 389
diff changeset
    40
padding the string at the beginning with NOP-instructions.  
33
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    41
\end{enumerate}
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    42
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    43
\end{document}
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    44
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    45
%%% Local Variables: 
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    46
%%% mode: latex
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    47
%%% TeX-master: t
Christian Urban <urbanc@in.tum.de>
parents:
diff changeset
    48
%%% End: