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Question about linux shellcode

 
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_cih_



Joined: Wed Sep 13, 2006 5:50 pm
Posts: 10

PostPosted: Fri Jan 05, 2007 1:36 am    Post subject: Question about linux shellcode Reply with quote

Hello everybody,

I am trying to write a simple shellcode, but I am having some difficulties.
i.e

I have following codes ( with following hex represenation respectively ) :

..
jmp 0x8048243<main+91> (e9 3a 00 00 00)
..
mov $0x9ed, %ecx (b9 ed 09 00 00)
..
js 0x804824f<main+103> (78 00)
..


As you can see the problem I have are the 00-s in the shellcode.If i want to overflow a character buffer, such null bytes will be considered as end of string. Can anybody hint me on any workaround on one of the samples above ?

Thanks.
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Steogede
LXF regular


Joined: Thu May 04, 2006 6:39 pm
Posts: 146

PostPosted: Tue Jan 16, 2007 10:13 am    Post subject: Re: Question about linux shellcode Reply with quote

_cih_ wrote:
Hello everybody,

I am trying to write a simple shellcode, but I am having some difficulties.
i.e

I have following codes ( with following hex represenation respectively ) :

..
jmp 0x8048243<main+91> (e9 3a 00 00 00)
..
mov $0x9ed, %ecx (b9 ed 09 00 00)
..
js 0x804824f<main+103> (78 00)
..


As you can see the problem I have are the 00-s in the shellcode.If i want to overflow a character buffer, such null bytes will be considered as end of string. Can anybody hint me on any workaround on one of the samples above ?

Thanks.


You have a shell that understands Assembly? Perhaps it would help if you mentioned which shell you are using, it certainly isn't BASH.
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jjmac
LXF regular


Joined: Fri Apr 08, 2005 2:32 am
Posts: 1996
Location: Sydney, Australia

PostPosted: Tue Jan 16, 2007 10:26 am    Post subject: RE: Re: Question about linux shellcode Reply with quote

>>
If i want to overflow a character buffer
>>

Why would you want to do that ?


jm
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