Re: Hidden Ports

[<vrsnet () pandora be>]

> Eduardo Sorensen wrote:
> > Can a port scanner not see a port that is opened?
> >
> > The question is: can a backdoor be on a machine, and with nmap -p 1-,
> > for example, you couldn't see it?
>
> Yes, this is quite common these days.  Rootkits like SucKIT can monitor
> all IP sessions on a host, and only open up the backdoor port when a
> certain trigger arrives via one of the already-open services.  For
example,
> if an attacker sends a certain string of bytes to the HTTP server on port
> 80 (even if the string is invalid HTTP).  Some tools also look for
> connections to ports in certain order (eg, the same host contacts port
> 80, port 22 and then port 443 within a few seconds).  Unless the trigger
> is received, then the backdoor isn't listening, and thus wouldn't show
> up in a portscan.
>
> There may be other more innovative triggers, too.  It's a hard problem.
If
> you think you might have a backdoor, you shouldn't depend solely on
> portscanners like nmap to detect it.  Anti-virus, tripwire and tools like
> chkrootkit are also necessary.
>
> David
>
> --
> David J. Bianco

For windows users this could be a usefull tool to detect rootkits
http://www.haxorcitos.com/ficheros/RKDetectorv0.61.zip



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