# ---------------------------------------------------------------
# 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"

# Do not accept requests without common headers. 
#
# Implies either an attacker or a legitimate automation client. 
#
SecRule REQUEST_URI "^/$" "chain,skip:4"
SecRule REMOTE_ADDR "^127\.0\.0\.1$" "chain"
SecRule REQUEST_HEADERS:User-Agent "^Apache.*\(internal dummy connection\)$" "t:none"

SecRule &REQUEST_HEADERS:Host "@eq 0" \
    "skip:1,deny,log,auditlog,status:400,msg:'Request Missing a Host Header',id:'960008',severity:'4'"
SecRule REQUEST_HEADERS:Host "^$" \
    "deny,log,auditlog,status:400,msg:'Request Missing a Host Header',id:'960008',severity:'4'"    


SecRule &REQUEST_HEADERS:Accept "@eq 0" \
    "chain,skip:1,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015'"
SecRule REQUEST_METHOD "!OPTIONS"
SecRule REQUEST_HEADERS:Accept "^$" \
    "chain,deny,log,auditlog,status:400,msg:'Request Missing an Accept Header', severity:'2',id:'960015'"
SecRule REQUEST_METHOD "!OPTIONS"

SecRule &REQUEST_HEADERS:User-Agent "@eq 0" \
    "skip:1,deny,log,auditlog,status:400,msg:'Request Missing a User Agent Header',id:'960009',severity:'4'"
SecRule REQUEST_HEADERS:User-Agent "^$" \
    "deny,log,auditlog,status:400,msg:'Request Missing a User Agent Header',id:'960009',severity:'4'"


# Check that the host header is not an IP address 
#
SecRule REQUEST_HEADERS:Host "^[\d\.]+$" "deny,log,auditlog,status:400,msg:'Host header is a numeric IP address', severity:'2',id:'960017'"
