Security Basics mailing list archives
Re: Environment use to inject shellcode
From: Daniele Endlesstars <endlesstars () gmail com>
Date: Sat, 24 Mar 2012 01:12:51 +0100
I've been asked to describe the procedure a little more in details. It mainly involves crafting a long series of null terminated nopsled. The limit for each is 128kB, and the limit for the whole stack is around 2MB so you can put 16 strings of a little less than 128kB. If you craft them directly and uses execve() you don't need to have the = in the name and you can have also share the name for several variables (in the case the name is just nops). To skip the null byte between the nopsleds i inserted a small near jump (2 bytes) at the end of every string, except the last one where i put the shellcode. This result that no matter where you land it will go down the stack until it finds the code. Wikipedia (http://en.wikipedia.org/wiki/Address_space_layout_randomization) tells me linux places the stack base in an area 8 MB wid, so with a 2MB nopsled you have a 1 out of 4 chance to hit the useful code, that is 16 more time than using a single environment variable. ------------------------------------------------------------------------ Securing Apache Web Server with thawte Digital Certificate In this guide we examine the importance of Apache-SSL and who needs an SSL certificate. We look at how SSL works, how it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates. http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442f727d1 ------------------------------------------------------------------------
Current thread:
- Environment use to inject shellcode Daniele Endlesstars (Mar 23)
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- Re: Environment use to inject shellcode Daniele Endlesstars (Mar 26)