Re: write-shellcode

[D Adusumalli <asndpp () gmail com>]

Andrew,

Seems like you have not set the JMP instruction appropriately.


On Sat, Oct 10, 2009 at 7:44 PM, Andrew Fast0w <aur0spy () gmail com> wrote:
> i am currently learning shellcoding. Am having a problem with the following :
>
> the asm code is a simple write followed by an exit syscall.This is working
> ---------------------------------------------------------------------------------------------------------------
> .text
> .globl _start
>
>        _start:
>                jmp stringaddr
>
>                ShellCode:
>                popl %esi
>                movb $0x4,%al
>                movb $0x1,%bl
>                movl %esi,%ecx
>                movb $0x5,%dl
>                int $0x80
>                xorl %eax,%eax
>                inc %eax
>                xorl %ebx,%ebx
>                inc %ebx
>                inc %ebx
>                int $0x80 #exit(2)
>
>                stringaddr:
>                Call ShellCode
>                string: .ascii "r00t\n"
> --------------------------------------------------------------------------------------------------
> Converted the above to shellcode
> -------------------------------------------------
> char 
> shellcode[]="\xeb\x14\x5e\xb0\x04\xb3\x01\x89\xf1\xb2\x05\xcd\x80\x31\xc0\x40\x31\xdb\x43\x43\xcd\x80\xe8\xe7\xff\xff\xff\x72\x30\x30\x74\x0a";
>
> int main()
> {
>        int *ret;
>        ret=(int*)&ret + 2;
>        (*ret)=(int)shellcode;
> }
> --------------------------------------------------------------------------------------------------
> the shellcode is getting executed b/c the exit value is of the program is 2.
> But am not getting the output of the write syscall !
>
> Can someone please explain why ?
>
> ------------------------------------------------------------------------
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> ------------------------------------------------------------------------

------------------------------------------------------------------------
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
------------------------------------------------------------------------