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Re: inline meterpreter payload
From: Richard Miles <richard.k.miles () googlemail com>
Date: Wed, 12 Sep 2012 12:26:22 -0500

Hi egypt

Thanks. In the case of the second stage for meterpreter, I guess that:

A) At point 2 (read a 4-byte length) you remotely check the size of
metsrv.dll, correct?

B) At point 5 ( read length bytes into that buffer) are you downloading
metsrv.dll, correct? Is it transferred as a .DLL ? Is there any evasion
here? I'm asking because as someone pointed out some proxies blocks .DLL
downloads and also some AV gateways may have signature for metsrv.dll, not?

C) Finally, is it possible to do step 6 ( jump to the buffer. easiest way
to do this in C is cast it to a function pointer and call it.) with a whole
.DLL in that buffer? My previous understand is that you needed a proper
shellcode to do it, since a DLL as specific loading that I was not aware
that could be accomplished by being called on this way.

For example, I was not aware that you could store a whole .DLL at "addr"
and execute it such as ((void (*)(void))addr)();

Thanks.

On Tue, Sep 11, 2012 at 5:13 PM, <egypt () metasploit com> wrote:

On Tue, Sep 11, 2012 at 4:40 PM, Chip <jeffschips () gmail com> wrote:
On 9/11/2012 5:35 PM, egypt () metasploit com wrote:

On Tue, Sep 11, 2012 at 4:31 PM, Richard Miles
<richard.k.miles () googlemail com> wrote:

Hi Joshua

For example, if I use shellcodeexec and it's not detected by AV the first
stage will be loaded on memory and it will download the second stage
(.dll)
and only run it from memory, right?

Thanks

The executables that Metasploit creates do not contain meterpreter,
just a stager stub that reads a 4-byte length followed by that many
bytes of a second stage. In the case of meterpreter, the second stage
is a Reflective DLL. Anything that can connect to a Metasploit handler
and follow the same steps will accomplish the same thing.

egypt
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I've been looking for this explanation for a long time.  Is there a
tutorial
on how to do exactly that -- connect a home-grown binary to the
Metasploit
handler in the proper fashion so it works?


No tutorials that I know of, but here are the basic steps:

1- connect to the handler
2- read a 4-byte length
3- allocate a length-byte buffer
4- mark it as writable and executable (on Windows you'll need
VirtualProtect for this)
5- read length bytes into that buffer
6- jump to the buffer. easiest way to do this in C is cast it to a
function pointer and call it.


Hope this helped,
egypt

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