Buffer Overflow Primer Part 2 (Writing Exit Shellcode)


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Posted On:	Mon 21 Feb 2011
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Description: Welcome to Part 2 of the Buffer Overflow Primer. If you have not already done so, please start this series by viewing Part 1. The Buffer Overflow Primer requires that you know at least some basic Assembly Language. I have created a series of Assembly Language video tutorials for Hackers here, for those not familiar with the language. <br><br>In this video we will look at how to create Shellcode which we can use as payload while exploiting a buffer overflow vulnerability. Shellcode is nothing but machine code which the CPU can execute directly without requiring any further assembling, compilation or linking. Thus instructions in the Shellcode will be executed as-is. We will look at the exit() syscall and see how we can convert the assembly language code for invoking it into shellcode. In the process, we will be using the Objdump utility which ships with the Binary utils package. After you have gone through this video, you will be able to convert almost any assembly code into it's shellcode equivalent.<br><br><br><br><style type="text/css">body { background: #FFF; } </style> </div>

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This video is part of the following groups:

1. Buffer Overflow Exploitation Megaprimer for Linux ( 9 videos)

Comments (20)

	H4TT1fn4TT on Fri 04 Mar 2011 Loose focus? I will not even loose focus if you make videos that are 6 hours long. Not of they are of this quality!
	_32_maheffa on Sun 13 Mar 2011 " H4TT1fn4TT on Fri 04 Mar 2011 Loose focus? I will not even loose focus if you make videos that are 6 hours long. Not of they are of this quality!" +1
	chronic_ on Mon 28 Mar 2011 Amazing video. These really help me as I am a visual learner. Reading about this confuses me.
	ElDanzante on Sat 02 Apr 2011 Great videos
	Col_Loki on Tue 26 Apr 2011 Great video, looking forward to more viewing tomorrow! Thanks.
	sekstiseks on Thu 05 May 2011 Excellent. =)
	FuzzyNop on Fri 27 May 2011 Good video as always
	3ntropy on Sat 18 Jun 2011 Hello Vivek! Thank you very much for your tutorials and help. You are helping us very much, I am personally learning more than I do at Uni. Tnak you again.
	Alteminor on Fri 24 Jun 2011 Excellent. Thanks. :)
	bsmartt on Sat 25 Jun 2011 Thanks vivek. Another great video. This is my second intro to shell code, the first was the Wiley press Shellcoder's handbook. You both explain almost exactly the same technique -- which is just testament to your teaching ability.
	smartboy on Thu 30 Jun 2011 Great video. Thanks.
	in0cula on Thu 21 Jul 2011 thank you Vivek
	E33 on Sun 07 Aug 2011 Excellent job as usual Vivek, I have a small problem, when i run gcc -static - o exit exit.c it gave some error: oot@bt:~/Files/codes open security/Buffer-Overflow-Primer/part2# gcc -static -o exit exit.c /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0xe5): undefined reference to `__rel_iplt_end' /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0xec): undefined reference to `__rel_iplt_start' /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0xfd): undefined reference to `__rel_iplt_start' /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0x106): undefined reference to `__rel_iplt_start' /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0x113): undefined reference to `__rel_iplt_start' /usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../lib/libc.a(elf-init.o): In function `__libc_csu_irel': (.text+0x11b): undefined reference to `__rel_iplt_start' collect2: ld returned 1 exit status can you please advise?
	rmathews7 on Mon 05 Sep 2011 Brilliant... loved the video and how everything was explained step by step. Looking forward to watch all videos.
	SpEcTeR on Thu 08 Sep 2011 Hello .Is there who know about segmentation fault. actually, I did any work like inside movie, step by step in my Vmware Machine with ubuntu 11 x86 but I couldn't fix that moreover I used -fno-stack-protector switch but it didn't work however is there anyone have a solution please help me .thanks
	estenole on Mon 12 Sep 2011 Hello all, Im a little bit confused, i have compiled the exit.c program but my disassemble is so different than vivek dump. Dump of assembler code for function main: 0x08048250 <+0>: push %ebp 0x08048251 <+1>: mov %esp,%ebp 0x08048253 <+3>: and $0xfffffff0,%esp 0x08048256 <+6>: sub $0x10,%esp 0x08048259 <+9>: movl $0x0,(%esp) 0x08048260 <+16>: call 0x8048b30 <exit> End of assembler dump. (gdb) disassemble exit Dump of assembler code for function exit: 0x08048b30 <+0>: push %ebp 0x08048b31 <+1>: mov %esp,%ebp 0x08048b33 <+3>: sub $0x18,%esp 0x08048b36 <+6>: mov 0x8(%ebp),%eax 0x08048b39 <+9>: movl $0x1,0x8(%esp) 0x08048b41 <+17>: movl $0x80c600c,0x4(%esp) 0x08048b49 <+25>: mov %eax,(%esp) 0x08048b4c <+28>: call 0x8048a30 <__run_exit_handlers> Whats the __run_exit_handlers ?? And why is my code so different ? Thank you
	van7hu_freenode on Sun 09 Oct 2011 >SpEcTeR on Thu 08 Sep 2011 > >Hello .Is there who know about segmentation fault. >actually, I did any work like inside movie, step by step >in my Vmware >Machine with ubuntu 11 x86 but I couldn't >fix that moreover >I used -fno-stack-protector switch but >it didn't work >however is there anyone have a solution >please help me .thanks http://en.wikipedia.org/wiki/Executable_space_protection
	hacknix on Thu 26 Jan 2012 I need someone who is capable of hacking* websites & accessing their email database I don't need scraping,web crawling or extractors I need this sites HACKED so I gain access to their email DB I will need to test the result u give me,if it checks out,I am willing to pay up to 3000$ per website and 10-20 websites monthly,which will increase upon delivery of faster & quality service Pls note,CONTINUITY is what I am after...I NEED A GOOD PARTNER I CAN WORK WITH FOR A VERY LONG TIME!. I HAVE AT LEAST 500 WEBSITES ON MY LIST AND IM WILLING TO PAY 3000$ PER WEBSITE PLEASE SEND ME A MAIL IF U CAN DO THIS ASAP ; omorye007 (at) yahoo (dot) com Cheers
	Inverse on Sun 12 Feb 2012 Hi Vivek video is simply amazing. But I have a doubt. I am using slackware64 bit, so when I disassemble my code, I get the assembly code according 64-bit architecture. I would like to know whether should I learn 64-bit architecture or not??? Will it be useful in future??? Thank You
	SeshaKiran on Thu 26 Apr 2012 Awesome. Loosing focus?? :) No way...

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Buffer Overflow Primer Part 2 (Writing Exit Shellcode)

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