Below is the recommended minimal mod_security
configuration. It is only a starting point designed not to give you an
instant headache. You should look into tightening the configuration where
you can.
# Turn ModSecurity On SecFilterEngine On # Reject requests with status 403 SecFilterDefaultAction "deny,log,status:403" # Some sane defaults SecFilterScanPOST On SecFilterCheckURLEncoding On SecFilterCheckUnicodeEncoding Off # Accept almost all byte values SecFilterForceByteRange 1 255 # Server masking is optional # SecServerSignature "Microsoft-IIS/5.0" SecUploadDir /tmp SecUploadKeepFiles Off # Only record the interesting stuff SecAuditEngine RelevantOnly SecAuditLog logs/audit_log # You normally won't need debug logging SecFilterDebugLevel 0 SecFilterDebugLog logs/modsec_debug_log # Only accept request encodings we know how to handle # we exclude GET requests from this because some (automated) # clients supply "text/html" as Content-Type SecFilterSelective REQUEST_METHOD "!^(GET|HEAD)$" chain SecFilterSelective HTTP_Content-Type \ "!(^application/x-www-form-urlencoded$|^multipart/form-data;)" # Do not accept GET or HEAD requests with bodies SecFilterSelective REQUEST_METHOD "^(GET|HEAD)$" chain SecFilterSelective HTTP_Content-Length "!^$" # Require Content-Length to be provided with # every POST request SecFilterSelective REQUEST_METHOD "^POST$" chain SecFilterSelective HTTP_Content-Length "^$" # Don't accept transfer encodings we know we don't handle SecFilterSelective HTTP_Transfer-Encoding "!^$"