Table Of ContentCoding for Penetration
Testers
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Coding for Penetration
Testers
Building Better Tools
Second Edition
Jason Andress
Ryan Linn
Clara Hartwell, Technical Editor
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Dedication
I would like to thank Anna and the folks at Syngress for all
of their contributions and assistance through this process.
Thanks to Heather for her support; without your aid, I’m
not sure this book would have ever happened. Thanks to Ed,
Kevin, HD, JCran, Egypt, Wade, Don, CG, JJ, Brian, and
the other mentors who have helped me along my security
career; all of your generosity and patience have helped me
grow to a point where I can share with others. Thanks to
the security community for being a generally awesome
group of people who are willing to share knowledge and
skills. To L0pht, Offsec, Corelan, and other security
researchers of today, thank you for the knowledge sharing
and explanations that are always pushing folks to learn
more; thanks for bringing your knowledge to the rest of the
community so that we can all learn. Thanks to Andrew,
Tom, and the rest of my coworkers at Nuix for your ideas
and support. Last, but not least, I would like to thank my
family. Thank you all for your support, guidance, cheering,
and, oh yeah, making sure I made it this far without being
eaten by wolves.
Ryan Linn
To Clara, thank you for always adventuring with me.
Jason Andress
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Contents
Aboutthe Authors...................................................................................................xv
CHAPTER 0 Introduction...................................................................1
BookOverview and Key LearningPoints....................................1
BookAudience..............................................................................2
How This Bookis Organized........................................................2
Chapter1:Introduction toCommand ShellScripting..............3
Chapter2:Introduction toPython.............................................3
Chapter3:Introduction toPerl.................................................3
Chapter4:Introduction toRuby...............................................3
Chapter5:Introduction toWeb Scripting With PHP...............4
Chapter6:Manipulating Windows With PowerShell..............4
Chapter7:Scanner Scripting....................................................4
Chapter8:Information Gathering.............................................4
Chapter9:Exploitation Scripting.............................................5
Chapter10:Postexploitation Scripting.....................................5
Conclusion.....................................................................................5
CHAPTER 1 Introduction to command shell scripting.....................7
On ShellScripting.........................................................................7
What Isa Shell?........................................................................8
What Isa Script?.......................................................................9
Shell Scripts.............................................................................10
Where Shell Scripting IsUseful?............................................10
UNIX, Linux, andOS XShell Scripting....................................11
Shell Availability and Choices................................................11
WorkingWith Shells...............................................................13
Bash Basics..................................................................................14
Hello World.............................................................................14
Variables..................................................................................16
Arguments................................................................................18
Controlstatements...................................................................19
Putting It All Together With Bash..............................................22
Adding /dev/tcp/supporttoBash.............................................23
Building aPort Scanner With Bash........................................23
Improvingthe Script................................................................25
vii
viii Contents
Windows Scripting......................................................................25
ShellAvailability and Choices................................................26
Command.comand CMD.exe.................................................26
PowerShell...............................................................................27
Cygwin.....................................................................................28
Other Shells.............................................................................28
PowerShell Basics.......................................................................29
HelloWorld.............................................................................29
Variables..................................................................................31
Arguments................................................................................32
ControlStatements..................................................................34
Conditionals.............................................................................34
Introducing the WindowsManagement Interface...................35
Looping....................................................................................36
Putting It All Together With PowerShell...................................38
Building a Port ScannerWith PowerShell..............................38
Improving the Script................................................................40
Summary......................................................................................41
References....................................................................................42
CHAPTER 2 Introduction to Python................................................43
What Is Python?..........................................................................44
WhereDo We Get Python?.....................................................44
WhereIs Python Useful?.............................................................44
Multiplatform Scripting...........................................................45
NetworkScripting....................................................................45
Extensive Modules..................................................................45
Reusable CodeThat IsEasy toCreate...................................45
Python Basics...............................................................................46
GettingStarted.........................................................................46
Variables..................................................................................48
Modules....................................................................................49
Arguments................................................................................49
Lists..........................................................................................53
Dictionaries..............................................................................56
ControlStatements..................................................................60
Functions..................................................................................62
FileManipulation........................................................................64
Exception Handling.................................................................65
Contents ix
NetworkCommunications...........................................................66
Client Communications...........................................................67
ServerCommunications..........................................................69
Scapy........................................................................................72
Summary......................................................................................78
References....................................................................................79
CHAPTER 3 Introduction to Perl.....................................................81
Introduction..................................................................................81
WherePerl IsUseful...................................................................82
HandlingText..........................................................................82
GluingApplications Together.................................................83
WorkingWith Perl......................................................................83
Editing Tools...........................................................................84
Extending Perl Scripts.............................................................85
Graphical User Interfaces inPerl............................................85
Perl Basics...................................................................................86
Hello World.............................................................................86
Variables..................................................................................87
Shell Commands......................................................................88
Arguments................................................................................91
ControlStatements..................................................................92
RegularExpressions................................................................97
File Input andOutput............................................................100
Putting It All Together..............................................................103
Building anSNMP ScannerWith Perl.................................103
Improvingthe Script..............................................................109
Summary....................................................................................109
References..................................................................................110
CHAPTER 4 Introduction to Ruby.................................................111
Introduction................................................................................111
WhereRubyIs Useful...............................................................112
RubyBasics...............................................................................112
Variables................................................................................114
Building Classes With Ruby.....................................................125
Building aClass.....................................................................126
Extending a Class..................................................................127
AccessingClass Data............................................................129
