<br><br><div class="gmail_quote">On Mon, Sep 26, 2011 at 12:02 PM, Abhijit Pawar <span dir="ltr"><<a href="mailto:apawar.linux@gmail.com">apawar.linux@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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On 09/23/2011 03:11 PM, rohan puri wrote:
<blockquote type="cite"><br>
<br>
<div class="gmail_quote">On Fri, Sep 23, 2011 at 2:43 PM, Abhijit
Pawar <span dir="ltr"><<a href="mailto:apawar.linux@gmail.com" target="_blank">apawar.linux@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>
<div> On 09/23/2011 02:04 PM, rohan puri wrote:
<blockquote type="cite"><br>
<br>
<div class="gmail_quote">On Fri, Sep 23, 2011 at 2:00
PM, Abhijit Pawar <span dir="ltr"><<a href="mailto:apawar.linux@gmail.com" target="_blank">apawar.linux@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<div>On 09/23/2011 01:01 PM, Rajat Sharma wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Untidy way :
-<br>
Yes, you can do that by registering a new
binary format handler. Whenever<br>
exec is called, a list of registered
binary format handlers is scanned, in<br>
the same way you can hook the
load_binary& load_library function
pointers<br>
of the already registered binary format
handlers.<br>
</blockquote>
Challenge with this untidy way is to
identify the correct format, for<br>
example if you are interested in only
hooking ELF format, there is no<br>
special signature withing the registered
format handler to identify<br>
that, however if one format handler
recognizes the file header, its<br>
load_binary will return 0. This can give you
the hint that you are<br>
sitting on top of correct file format. Long
time back I had written<br>
the similar module in Linux to do the same,
but can't share the code<br>
:)<br>
<br>
-Rajat<br>
<br>
On Thu, Sep 22, 2011 at 3:14 PM, rohan
puri<<a href="mailto:rohan.puri15@gmail.com" target="_blank">rohan.puri15@gmail.com</a>>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <br>
On Thu, Sep 22, 2011 at 1:53 PM, Abhijit
Pawar<<a href="mailto:apawar.linux@gmail.com" target="_blank">apawar.linux@gmail.com</a>><br>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> hi list,<br>
Is there any way to hook the exec system
call on Linux box apart from<br>
replacing the call in System Call table?<br>
<br>
Regards,<br>
Abhijit Pawar<br>
<br>
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</blockquote>
Tidy way : -<br>
<br>
You can do that from LSM (Linux security
module).<br>
<br>
Untidy way : -<br>
Yes, you can do that by registering a new
binary format handler. Whenever<br>
exec is called, a list of registered
binary format handlers is scanned, in<br>
the same way you can hook the
load_binary& load_library function
pointers<br>
of the already registered binary format
handlers.<br>
<br>
Regards,<br>
Rohan Puri<br>
<br>
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<br>
<br>
</blockquote>
</blockquote>
</div>
</div>
So If I use the binary format handler, then I can
hook the exec call. however I need to register
this. Does that mean that I need to return the
negative value so as to have actual ELF handler to
be loaded?<br>
<br>
Regards,<br>
<font color="#888888"> Abhijit Pawar<br>
<br>
</font></blockquote>
</div>
Read this, <a href="http://www.linux.it/%7Erubini/docs/binfmt/binfmt.html" target="_blank">http://www.linux.it/~rubini/docs/binfmt/binfmt.html</a>
this might help<br>
<br>
Regards,<br>
Rohan Puri<br>
</blockquote>
</div>
</div>
Thanks Rohan. I tried creating a hooking module on the
similar line. I am able to load the module but whenever I am
launching any application , its load_binary is not being
called.<br>
here is the source for the module attached.<br>
<br>
Regards,<br>
<font color="#888888"> Abhijit Pawar<br>
<br>
<br>
</font></div>
</blockquote>
</div>
<br>
Hi Abhijit,<br>
<br>
I have made the change, try to compile and execute this code, it
works.<br>
<br>
Also, I am just curious enough to know that where do you need to
do this hooking.<br>
<br>
Regards,<br>
Rohan Puri<br>
</blockquote></div></div>
Hi Rohan,<br>
I have been looking at Windows worlds ability to support DLL
Injection and API hooking. I was just wondering if this could be
something to be done in Linux as well. I am not sure if there is
any special use of this module apart from learning the binary
handler. May be it could be used as a security module for your own
binary handler.<br>
<br>
Regards,<br><font color="#888888">
Abhijit Pawar<br>
</font></div>
</blockquote></div><br>Hi Abhijit,<br><br>I am not familiar with windows. Special use-case of this hacking is for security companies whitelisting software solutions, where they want to control execution of only authorized binaries on the system and deny the execution of others.<br>
<br><br>Although this approach is untidy, since there is available LSM hooks in linux kernel which needs to be made use of for doing this.<br><br>Regards,<br>Rohan Puri<br>