Re: Sending remote procedure calls through e-mail (RPC-Mail)

[Cristiano Lincoln Mattos <lincoln () tempest com br>]

On Wednesday 20 October 2004 00:27, Abe Usher wrote:

        what you have is basically unencrypted and weakly authenticated command 
execution on the system, since all you rely on is the secrecy of the "special 
account" and a simple passphrase -- both can be sniffed, or the account 
gathered from mail server logs. not exactly secure.  

        be nice to see the system trying to execute "Get slim without Gym!" if a
spam with the passprase in the body reached the account :) 

Cristiano Lincoln Mattos

> Have you ever had the need to remotely send a command to a system, but
> you could not access it directly via ssh or telnet because the firewall
> is blocking all inbound connections?
>
> The practice of portknocking <http://www.portknocking.org/> provides an
> interesting network authentication mechanism for establishing a
> connection to a networked computer that has no open ports (as advertised
> on portknocking.org).
>
> While I find portknocking ingenious, it is somewhat cumbersome and
> overly complex for most users. I propose an alternative - send remote
> procedure calls via e-mail. I've coded an application that fits the
> bill: RPC-Mail.
>
> The premise of RPC-Mail is simple:
> (1) Construct an e-mail message that has a command that you want one of
> your remote PCs to execute.
> (2) Send the e-mail to a special account that is only used by RPC-Mail.
> (3) Have the remote PC set up with a scheduled task or cron job to
> periodically execute the application RPC-Mail.py.
> (4) When RPC-Mail.py executes, it parses all of the subject lines and
> message bodies of e-mail messages that it finds. If the message body
> contains a special passphrase, RPC-Mail executes the subject line as a
> command, and returns standard output as an e-mail message.
>
> For more information check out my full write up on:
> http://www.sharp-ideas.net/
>
> Cheers,
> Abe Usher, CISSP
>
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-- 
Cristiano Lincoln Mattos
Tempest Security Technologies - www.tempest.com.br
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