Assembly Primer For Hackers (Part 7) Working With Strings
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Description: This is Part 7 of the "Assembly Language Primer for Hackers" video series. Please begin here, by watching Part 1, if you have not already done so. In this video we will look at how to work with strings in Assembly. We will demonstrate how we can move strings from one memory location to the other using the MOVS instruction set, discuss the concept of the Direction Flag (DF) and how to set and clear it using STD and CLD, how to execute multiple string copy instructions using the REP instruction, how to load strings from memory into the EAX register using the LODS instruction set, how to store strings from the EAX register back into memory using the STOS instruction set and finally we shall look at how to compare strings using the CMPS instruction set.
Please download StringBasics.s to try out the various exercises discussed in this video.
This video is part of the following groups:
1. Assembly Language Megaprimer for Linux ( 11 videos)
Comments (17)
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cr1tt3r on Sat 26 Feb 2011 Why do we need the "nop" instruction at the beginning of the _start function? |
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paul on Mon 07 Mar 2011 I was wondering the same thing, what is the "nop" instruction? |
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sogood on Tue 15 Mar 2011 nop is no operation. Just a void command used to set breakpoint or locate code more easily. |
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sogood on Tue 15 Mar 2011 I believe there's a typo in REP slide: "till" should be "while". Based on your debug, REP stops when ECX (length) = 0, so it keeps going "while >0" |
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Col_Loki on Sat 30 Apr 2011 Very good video, i spotted the typo too...was thinking it should be till ECX = 0. |
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3ntropy on Fri 10 Jun 2011 YOu are great man! Better than Univer.teachers here,(I am not gonna tell you 'where'). Very well informed instructions. Do you have got tutorials on format string vuln.(I found some of your tutorials), but with a shell execetion from the memory, I am trying with DTORS, but I am finding it difficult. |
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nkb on Fri 24 Jun 2011 Awesome video ...Thanks for all the efforts u put in to this !! |
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maver1kk on Fri 01 Jul 2011 Why do you use: |
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brownman on Fri 01 Jul 2011 your vids r awesome! |
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lardycake on Thu 07 Jul 2011 Starting to get more complicated, but these guides are really well made so it's a lot easier to follow than learning from scratch from a book. |
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xplt on Fri 08 Jul 2011 As always! Another great movie! Thank you Vivek! |
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ipatch on Wed 13 Jul 2011 36 minutes, this was a long one. |
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neo on Fri 15 Jul 2011 great video. |
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mac on Fri 05 Aug 2011 well!!! it was good one literally as expected every new episode is exciting and much adventurous going great plese make some more videos linux primer 11 ,12,13 & so on ........................ |
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ian on Thu 11 Aug 2011 @col_Loki |
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orrala on Sat 01 Oct 2011 excellent work :) |
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Jenny on Thu 20 Oct 2011 Great material, great presentation. Thank you so much! |