Re: FreeBSD's RST validation

From: Tristan Horn (tristan+-eyjgmdat_private)
Date: Sun Aug 30 1998 - 22:30:34 PDT

  • Next message: Darren Reed: "port scanning. (fwd)"

    On Sun, Aug 30, 1998 at 06:22:26PM -0700, James Snow wrote:
    > Be aware that this individual used this attack on my machine late last
    > night, disconnecting all of my users without warning, and certainly
    > without asking for permission.
    
    As before, I apologize for disconnecting those three random IRC sessions,
    though I don't think that's relevant to this forum.
    
    > He also did not, to my knowledge, report this to the FreeBSD team before
    > posting this here.
    
    Yeah, I only Bcc'd security-officerat_private  Sorry, prior experience
    led me to believe that it would take a day or so before the message would
    be approved...
    
    Probably not entirely FreeBSD-specific, anyway.
    
    On Sun, Aug 30, 1998 at 07:09:46PM -0700, Diane Bruce wrote:
    > I hate people who mime their email for the plain text part.
    
    OK, I won't sign this one.
    
    > Port 6666 is quite commonly used for autoconnect, as well as 31337...
    > Not really very much that can be done from userland really...
    
    I'm told that 5555 is something of a standard these days too.
    
    If you can effectively keep /both/ ports unknown, i.e. bind to a random
    port for outbound server connections and get your uplink to set up a
    special port (firewalled from portscanners), you'd be in good shape.
    
    However, I doubt most people would be willing to go to such trouble, and
    I think it takes enough additional brainpower to keep it from being
    exploited much before the patch is released anyway.
    
    The offending code seems to be around /usr/src/sys/netinet/tcp_input.c:809
    for sockets in SYN_SENT state, and :1138 for sockets in most of the other
    states.  (Looking at 2.2.6-RELEASE: $Id: tcp_input.c,v 1.54.2.7...)
    
    On a similar topic, has anyone explored the possibility of injecting
    routes or doing other evil things with the endlses information that ciscos
    provide in sh ip bgp nei?  Most route-views type places seem to allow it.
    
    Tris
    



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