# ---------------------------------------------------------------
# Core ModSecurity Rule Set
# Copyright (C) 2006 Breach Security Inc. All rights reserved.
#
# The ModSecuirty Core Rule Set is distributed under GPL version 2
# Please see the enclosed LICENCE file for full details.
# ---------------------------------------------------------------


#
# TODO in some cases a valid client (usually automated) generates requests that
#      violates the HTTP protocol. Create exceptions for those clients, but try
#      to limit the exception to a source IP or other additional properties of 
#      the request such as URL and not allow the violation generally. 
#  
#

# Use status code 400 response status code by default as protocol violations 
# are in essence bad requests.
SecDefaultAction "log,pass,phase:1,status:400"

# Accept only digits in content length 
#
SecRule REQUEST_HEADERS:Content-Length "!^\d+$" "deny,log,auditlog,status:400,msg:'Content-Length HTTP header is not numeric', severity:'2',id:'960016'"

# Do not accept GET or HEAD requests with bodies
# HTTP standard allows GET requests to have a body but this
# feature is not used in real life. Attackers could try to force
# a request body on an unsuspecting web applications.
#
SecRule REQUEST_METHOD "^(GET|HEAD)$" "chain,deny,log,auditlog,status:400,msg:'GET or HEAD requests with bodies', severity:'2',id:'960011'"
SecRule REQUEST_HEADERS:Content-Length "!^0?$"

# Require Content-Length to be provided with every POST request.
#
SecRule REQUEST_METHOD "^POST$" "chain,deny,log,auditlog,status:400,msg:'POST request must have a Content-Length header',id:'960012',severity:'4'"
SecRule &REQUEST_HEADERS:Content-Length "@eq 0"

# Don't accept transfer encodings we know we don't know how to handle
#
# NOTE ModSecurity does not support chunked transfer encodings at
#      this time. You MUST reject all such requests.
#
SecRule HTTP_Transfer-Encoding "!^$" "deny,log,auditlog,status:501,msg:'ModSecurity does not support transfer encodings',id:'960013',severity:'5'"

# Check decodings
SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES|REQUEST_HEADERS|!REQUEST_HEADERS:Referer "@validateUrlEncoding" \
	"chain, deny,log,auditlog,status:400,msg:'URL Encoding Abuse Attack Attempt',id:'950107',severity:'4'"
SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES|REQUEST_HEADERS|!REQUEST_HEADERS:Referer "\%(?![0-9a-fA-F]{2}|u[0-9a-fA-F]{4})"

SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES|REQUEST_HEADERS|!REQUEST_HEADERS:Referer "@validateUtf8Encoding" "deny,log,auditlog,status:400,msg:'UTF8 Encoding Abuse Attack Attempt',id:'950801',severity:'4'"

# Proxy access attempt
# NOTE Apache blocks such access by default if not set as a proxy. The rule is 
#      included in case Apache proxy is misconfigured.
SecRule REQUEST_URI ^http:/ "deny,log,auditlog,status:400,msg:'Proxy access attempt', severity:'2',id:'960014'"

#
# Restrict type of characters sent
#
# NOTE In order to be broad and support localized applications this rule
#      only validates that NULL Is not used.
#
#	   The strict policy version also validates that protocol and application 
#	   generated fields are limited to printable ASCII. 
#
# TODO If your application use the range 32-126 for parameters.
#
SecRule REQUEST_FILENAME|REQUEST_HEADERS_NAMES|REQUEST_HEADERS|!REQUEST_HEADERS:Referer \
	"@validateByteRange 32-126" \
	"deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015',t:urlDecodeUni,phase:1"

SecRule ARGS|ARGS_NAMES "@validateByteRange 1-255" \
	"deny,log,auditlog,status:400,msg:'Invalid character in request',id:'960901',severity:'4',t:urlDecodeUni,phase:2"