# ---------------------------------------------------------------
# Core ModSecurity Rule Set ver.1.6.1
# Copyright (C) 2006-2007 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. 
#  
#

# Validate request line
#
SecRule REQUEST_LINE "!^(?:(?:[a-z]{3,10}\s+(?:\w{3,7}?://[\w\-\./]*(?::\d+)?)?/[^?#]*(?:\?[^#\s]*)?(?:#[\S]*)?|connect (?:\d{1,3}\.){3}\d{1,3}\.?(?::\d+)?|options \*)\s+[\w\./]+|get /[^?#]*(?:\?[^#\s]*)?(?:#[\S]*)?)$" \
    "t:none,t:lowercase,phase:2,deny,log,auditlog,status:400,msg:'Invalid HTTP Request Line',id:'960911',severity:'2'"


# HTTP Request Smuggling
#
SecRule REQUEST_HEADERS:'/(Content-Length|Transfer-Encoding)/' "," "phase:2,t:none,deny,log,auditlog,status:400,msg:'HTTP Request Smuggling Attack.',id:'950012',tag:'WEB_ATTACK/REQUEST_SMUGGLING',severity:'1'"

# Block request with malformed content.
# ModSecurity will not inspect these, but the server application might do so
#
SecRule REQBODY_PROCESSOR_ERROR "!@eq 0" "t:none,phase:2,deny,log,auditlog,status:400,msg:'Request Body Parsing Failed. %{REQBODY_PROCESSOR_ERROR_MSG}',id:'960912',severity:'2'"


# Accept only digits in content length 
#
SecRule REQUEST_HEADERS:Content-Length "!^\d+$" "phase:2,t:none,deny,log,auditlog,status:400,msg:'Content-Length HTTP header is not numeric', severity:'2',id:'960016',tag:'PROTOCOL_VIOLATION/INVALID_HREQ'"

# 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)$" "chain,phase:2,t:none,deny,log,auditlog,status:400,msg:'GET or HEAD requests with bodies', severity:'2',id:'960011',tag:'PROTOCOL_VIOLATION/EVASION'"
SecRule REQUEST_HEADERS:Content-Length "!^0?$" t:none

# Require Content-Length to be provided with every POST request.
#
SecRule REQUEST_METHOD "^POST$" "chain,phase:2,t:none,deny,log,auditlog,status:400,msg:'POST request must have a Content-Length header',id:'960012',tag:'PROTOCOL_VIOLATION/EVASION',severity:'4'"
SecRule &REQUEST_HEADERS:Content-Length "@eq 0" t:none

# 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 REQUEST_HEADERS:Transfer-Encoding "!^$" "phase:2,t:none,deny,log,auditlog,status:501,msg:'ModSecurity does not support transfer encodings',id:'960013',tag:'PROTOCOL_VIOLATION/EVASION',severity:'3'"

# Check encodings
SecRule REQUEST_BODY|REQUEST_URI|XML:/* "\%(?!$|\W|[0-9a-fA-F]{2}|u[0-9a-fA-F]{4})" \
	"chain,phase:2,t:none,deny,log,auditlog,status:400,msg:'URL Encoding Abuse Attack Attempt',id:'950107',tag:'PROTOCOL_VIOLATION/EVASION',severity:'4'"
SecRule REQUEST_BODY|REQUEST_URI|XML:/* "@validateUrlEncoding"

# Check UTF enconding
# Uncomment this rule if your system uses UTF encoding.
#SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES|REQUEST_HEADERS|XML:/*|!REQUEST_HEADERS:Referer "@validateUtf8Encoding" "phase:2,t:none,deny,log,auditlog,status:400,msg:'UTF8 Encoding Abuse Attack Attempt',id:'950801',tag:'PROTOCOL_VIOLATION/EVASION',severity:'4'"

# Disallow use of full-width unicode
SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES|REQUEST_HEADERS|XML:/*|!REQUEST_HEADERS:Referer "\%u[fF]{2}[0-9a-fA-F]{2}" \
  "t:none,phase:2,deny,log,auditlog,status:400,msg:'Unicode Full/Half Width Abuse Attack Attempt',id:'950116',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_RAW ^\w+:/ "phase:2,t:none,deny,log,auditlog,status:400,msg:'Proxy access attempt', severity:'2',id:'960014',tag:'PROTOCOL_VIOLATION/PROXY_ACCESS'"

#
# 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" \
	"phase:2,deny,log,auditlog,status:400,msg:'Invalid character in request',id:'960018',tag:'PROTOCOL_VIOLATION/EVASION',severity:'4',t:none,t:urlDecodeUni"

SecRule ARGS|ARGS_NAMES|REQUEST_HEADERS:Referer "@validateByteRange 1-255" \
	"phase:2,deny,log,auditlog,status:400,msg:'Invalid character in request',id:'960901',tag:'PROTOCOL_VIOLATION/EVASION',severity:'4',t:none,t:urlDecodeUni"
