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REQUEST-920-PROTOCOL-ENFORCEMENT.conf
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REQUEST-920-PROTOCOL-ENFORCEMENT.conf
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# ------------------------------------------------------------------------
# OWASP ModSecurity Core Rule Set ver.3.2.0
# Copyright (c) 2006-2019 Trustwave and contributors. All rights reserved.
#
# The OWASP ModSecurity Core Rule Set is distributed under
# Apache Software License (ASL) version 2
# Please see the enclosed LICENSE file for full details.
# ------------------------------------------------------------------------
#
# Some protocol violations are common in application layer attacks.
# Validating HTTP requests eliminates a large number of application layer attacks.
#
# The purpose of this rules file is to enforce HTTP RFC requirements that state how
# the client is supposed to interact with the server.
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html
#
# -= Paranoia Level 0 (empty) =- (apply unconditionally)
#
SecRule TX:EXECUTING_PARANOIA_LEVEL "@lt 1" "id:920011,phase:1,pass,nolog,skipAfter:END-REQUEST-920-PROTOCOL-ENFORCEMENT"
SecRule TX:EXECUTING_PARANOIA_LEVEL "@lt 1" "id:920012,phase:2,pass,nolog,skipAfter:END-REQUEST-920-PROTOCOL-ENFORCEMENT"
#
# -= Paranoia Level 1 (default) =- (apply only when tx.executing_paranoia_level is sufficiently high: 1 or higher)
#
#
# Validate request line against the format specified in the HTTP RFC
#
# -=[ Rule Logic ]=-
#
# Uses rule negation against the regex for positive security. The regex specifies the proper
# construction of URI request lines such as:
#
# "http:" "//" host [ ":" port ] [ abs_path [ "?" query ]]
#
# It also outlines proper construction for CONNECT, OPTIONS and GET requests.
#
# -=[ References ]=-
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.2.1
# http://capec.mitre.org/data/definitions/272.html
#
SecRule REQUEST_LINE "!@rx ^(?i:(?:[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]*)?)$" \
"id:920100,\
phase:2,\
block,\
t:none,\
msg:'Invalid HTTP Request Line',\
logdata:'%{request_line}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_REQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
#
# Identify multipart/form-data name evasion attempts
#
# There are possible impedance mismatches between how
# ModSecurity interprets multipart file names and how
# a destination app server such as PHP might parse the
# Content-Disposition data:
#
# filename-parm := "filename" "=" value
#
# -=[ Rule Logic ]=-
# These rules check for the existence of the ' " ; = meta-characters in
# either the file or file name variables.
# HTML entities may lead to false positives, why they are allowed on PL1.
# Negative look behind assertions allow frequently used entities &_;
#
# -=[ Targets, characters and html entities ]=-
#
# 920120: PL1 : FILES_NAMES, FILES
# ['\";=] but allowed:
# &[aAoOuUyY]uml); &[aAeEiIoOuU]circ; &[eEiIoOuUyY]acute;
# &[aAeEiIoOuU]grave; &[cC]cedil; &[aAnNoO]tilde; & '
#
# 920121: PL2 : FILES_NAMES, FILES
# ['\";=] : ' " ; = meta-characters
#
# Not supported by re2 (?<!re).
#
# -=[ References ]=-
# https://www.owasp.org/index.php/ModSecurity_CRS_RuleID-960000
# http://www.ietf.org/rfc/rfc2183.txt
#
SecRule FILES_NAMES|FILES "@rx (?<!&(?:[aAoOuUyY]uml)|&(?:[aAeEiIoOuU]circ)|&(?:[eEiIoOuUyY]acute)|&(?:[aAeEiIoOuU]grave)|&(?:[cC]cedil)|&(?:[aAnNoO]tilde)|&(?:amp)|&(?:apos));|['\"=]" \
"id:920120,\
phase:2,\
block,\
t:none,t:urlDecodeUni,\
msg:'Attempted multipart/form-data bypass',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_REQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Accept only digits in content length
#
# -=[ Rule Logic ]=-
# This rule uses ModSecurity's rule negation against the regex meaning if the Content-Length header
# is NOT all digits, then it will match.
#
# -=[ References ]=-
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.13
#
SecRule REQUEST_HEADERS:Content-Length "!@rx ^\d+$" \
"id:920160,\
phase:1,\
block,\
t:none,\
msg:'Content-Length HTTP header is not numeric.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# 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.
#
# -=[ Rule Logic ]=-
# This is a chained rule that first checks the Request Method. If it is a
# GET or HEAD method, then it checks for the existence of a Content-Length
# header. If the header exists and its payload is either not a 0 digit or not
# empty, then it will match.
#
# -=[ References ]=-
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.3
#
SecRule REQUEST_METHOD "@rx ^(?:GET|HEAD)$" \
"id:920170,\
phase:2,\
block,\
t:none,\
msg:'GET or HEAD Request with Body Content.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule REQUEST_HEADERS:Content-Length "!@rx ^0?$" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# This is a sibling of rule 920170
#
SecRule REQUEST_METHOD "@rx ^(?:GET|HEAD)$" \
"id:920171,\
phase:2,\
block,\
t:none,\
msg:'GET or HEAD Request with Transfer-Encoding.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule &REQUEST_HEADERS:Transfer-Encoding "!@eq 0" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Require Content-Length or Transfer-Encoding to be provided with
# every POST request.
#
# -=[ Rule Logic ]=-
# This chained rule checks if the request method is POST, if so,
# it checks that a Content-Length or Transfer-Encoding headers are
# also present.
#
SecRule REQUEST_METHOD "@rx ^POST$" \
"id:920180,\
phase:2,\
block,\
t:none,\
msg:'POST without Content-Length or Transfer-Encoding headers.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
tag:'CAPEC-272',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
chain"
SecRule &REQUEST_HEADERS:Content-Length "@eq 0" \
"chain"
SecRule &REQUEST_HEADERS:Transfer-Encoding "@eq 0" \
"setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
#
# Range Header Checks
#
# 1. Range Header exists and begins with 0 - normal browsers don't do this.
# Automated programs and bots often do not obey the HTTP RFC
#
# -=[ Rule Logic ]=-
# This rule inspects the Range request header to see if it starts with 0.
#
# -=[ References ]=-
# http://www.bad-behavior.ioerror.us/about/
# https://tools.ietf.org/html/rfc7233
#
# 2. Per RFC 2616 -
# "If the last-byte-pos value is present, it MUST be greater than or equal to the first-byte-pos in that byte-range-spec,
# or the byte- range-spec is syntactically invalid."
# -=[ Rule Logic ]=-
# This rule compares the first and second byte ranges and flags when the first value is greater than the second.
#
# -=[ References ]=-
# https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
# http://seclists.org/fulldisclosure/2011/Aug/175
#
SecRule REQUEST_HEADERS:Range|REQUEST_HEADERS:Request-Range "@rx (\d+)\-(\d+)\," \
"id:920190,\
phase:2,\
block,\
capture,\
t:none,\
msg:'Range: Invalid Last Byte Value.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
chain"
SecRule TX:2 "!@ge %{tx.1}" \
"setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
#
# Broken/Malicous clients often have duplicate or conflicting headers
# Automated programs and bots often do not obey the HTTP RFC
#
# -=[ Rule Logic ]=-
# This rule inspects the Connection header and looks for duplicates of the
# keep-alive and close options.
#
# -=[ References ]=-
# http://www.bad-behavior.ioerror.us/about/
# https://tools.ietf.org/html/rfc7233
#
SecRule REQUEST_HEADERS:Connection "@rx \b(?:keep-alive|close),\s?(?:keep-alive|close)\b" \
"id:920210,\
phase:2,\
block,\
t:none,\
msg:'Multiple/Conflicting Connection Header Data Found.',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/INVALID_HREQ',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
#
# Check URL encodings
#
# -=[ Rule Logic ]=-
# There are two different chained rules. We need to separate them as we are inspecting two
# different variables - REQUEST_URI and REQUEST_BODY. For REQUEST_BODY, we only want to
# run the @validateUrlEncoding operator if the content-type is application/x-www-form-urlencoding.
#
# -=[ References ]=-
# http://www.ietf.org/rfc/rfc1738.txt
#
# -=[ Example payload ]=-
# http://localhost/?s=a%20b%20c%'/
# reason: %'/ is not a valid url encoding
#
SecRule REQUEST_URI "@rx \x25" \
"id:920220,\
phase:2,\
block,\
t:none,\
msg:'URL Encoding Abuse Attack Attempt',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/EVASION',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
chain"
SecRule REQUEST_URI "@validateUrlEncoding" \
"setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
SecRule REQUEST_HEADERS:Content-Type "@rx ^(?i)application/x-www-form-urlencoded" \
"id:920240,\
phase:2,\
block,\
t:none,\
msg:'URL Encoding Abuse Attack Attempt',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/EVASION',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
chain"
SecRule REQUEST_BODY "@rx \x25" \
"chain"
SecRule REQUEST_BODY "@validateUrlEncoding" \
"setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
#
# Check UTF enconding
# We only want to apply this check if UTF-8 encoding is actually used by the site, otherwise
# it will result in false positives.
#
# -=[ Rule Logic ]=-
# This chained rule first checks to see if the admin has set the TX:CRS_VALIDATE_UTF8_ENCODING
# variable in the crs-setup.conf file.
#
SecRule TX:CRS_VALIDATE_UTF8_ENCODING "@eq 1" \
"id:920250,\
phase:2,\
block,\
t:none,\
msg:'UTF8 Encoding Abuse Attack Attempt',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/EVASION',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
chain"
SecRule REQUEST_FILENAME|ARGS|ARGS_NAMES "@validateUtf8Encoding" \
"setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
#
# Disallow use of full-width unicode as decoding evasions may be possible.
#
# -=[ Rule Logic ]=-
# This rule looks for full-width encoding by looking for %u followed by 2 'f'
# characters and then 2 hex characters. It is a vulnerability that affected
# IIS circa 2007.
# The rule will trigger on %uXXXX formatted chars that are full or half
# width, as explained above. This %uXXXX format is passed as a raw parameter
# and is (seemingly only) accepted by IIS (5.0, 6.0, 7.0, and 8.0). Other
# webservers will only process unicode chars presented as hex UTF-8 bytes.
#
# -=[ References ]=-
# http://www.kb.cert.org/vuls/id/739224
# https://www.checkpoint.com/defense/advisories/public/2007/cpai-2007-201.html
# https://github.com/SpiderLabs/owasp-modsecurity-crs/issues/719
#
SecRule REQUEST_URI|REQUEST_BODY "@rx \%u[fF]{2}[0-9a-fA-F]{2}" \
"id:920260,\
phase:2,\
block,\
t:none,\
msg:'Unicode Full/Half Width Abuse Attack Attempt',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-iis',\
tag:'platform-windows',\
tag:'attack-protocol',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
#
# Restrict type of characters sent
#
# This is a rule with multiple stricter siblings that grows more
# restrictive in higher paranoia levels.
#
# -=[ Rule Logic ]=-
# This rule uses the @validateByteRange operator to restrict the request
# payloads.
#
# -=[ Targets and ASCII Ranges ]=-
#
# 920270: PL1 : REQUEST_URI, REQUEST_HEADERS, ARGS and ARGS_NAMES
# ASCII 1-255 : Full ASCII range without null character
#
# 920271: PL2 : REQUEST_URI, REQUEST_HEADERS, ARGS and ARGS_NAMES
# ASCII 9,10,13,32-126,128-255 : Full visible ASCII range, tab, newline
#
# 920272: PL3 : REQUEST_URI, REQUEST_HEADERS, ARGS, ARGS_NAMES and REQUEST_BODY
# ASCII 32-36,38-126 : Visible lower ASCII range without percent symbol
#
# 920273: PL4 : ARGS, ARGS_NAMES and REQUEST_BODY
# ASCII 38,44-46,48-58,61,65-90,95,97-122
# A-Z a-z 0-9 = - _ . , : &
#
# 920274: PL4 : REQUEST_HEADERS without User-Agent, Referer and Cookie
# ASCII 32,34,38,42-59,61,65-90,95,97-122
# A-Z a-z 0-9 = - _ . , : & " * + / SPACE
#
# REQUEST_URI and REQUEST_HEADERS User-Agent, Referer and Cookie are very hard
# to restrict beyond the limits in 920272.
#
# 920274 generally has few positives. However, it would detect rare attacks
# on Accept request headers and friends.
SecRule REQUEST_URI|REQUEST_HEADERS|ARGS|ARGS_NAMES "@validateByteRange 1-255" \
"id:920270,\
phase:2,\
block,\
t:none,t:urlDecodeUni,\
msg:'Invalid character in request (null character)',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/EVASION',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.anomaly_score_pl1=+%{tx.error_anomaly_score}'"
#
# Do not accept requests without common headers.
# All normal web browsers include Host, User-Agent and Accept headers.
# Implies either an attacker or a legitimate automation client.
#
#
# Missing/Empty Host Header
#
# -=[ Rule Logic ]=-
# These rules will first check to see if a Host header is present.
# The second check is to see if a Host header exists but is empty.
#
SecRule &REQUEST_HEADERS:Host "@eq 0" \
"id:920280,\
phase:2,\
pass,\
t:none,\
msg:'Request Missing a Host Header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_HOST',\
tag:'WASCTC/WASC-21',\
tag:'OWASP_TOP_10/A7',\
tag:'PCI/6.5.10',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}',\
skipAfter:END-HOST-CHECK"
SecRule REQUEST_HEADERS:Host "@rx ^$" \
"id:920290,\
phase:2,\
pass,\
t:none,\
msg:'Empty Host Header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_HOST',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
SecMarker "END-HOST-CHECK"
#
# Empty Accept Header
#
# -=[ Rule Logic ]=-
# This rule checks if an Accept header exists, but has an empty value.
# This is only allowed in combination with the OPTIONS method.
# Additionally, there are some clients sending empty Accept headers.
# They are covered in another chained rule checking the User-Agent.
# This technique demands a separate rule to detect an empty
# Accept header if there is no user agent. This is checked via
# the separate rule 920311.
#
# Exclude some common broken clients sending empty Accept header:
# "Business/6.6.1.2 CFNetwork/758.5.3 Darwin/15.6.0" (CRS issue #515)
# "Entreprise/6.5.0.177 CFNetwork/758.4.3 Darwin/15.5.0" (CRS issue #366)
#
# -=[ References ]=-
# https://github.com/SpiderLabs/owasp-modsecurity-crs/issues/366
#
SecRule REQUEST_HEADERS:Accept "@rx ^$" \
"id:920310,\
phase:2,\
pass,\
t:none,\
msg:'Request Has an Empty Accept Header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_ACCEPT',\
ver:'OWASP_CRS/3.2.0',\
severity:'NOTICE',\
chain"
SecRule REQUEST_METHOD "!@rx ^OPTIONS$" \
"chain"
SecRule REQUEST_HEADERS:User-Agent "!@pm AppleWebKit Android Business Enterprise Entreprise" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
#
# This rule is a sibling of rule 920310.
#
SecRule REQUEST_HEADERS:Accept "@rx ^$" \
"id:920311,\
phase:2,\
pass,\
t:none,\
msg:'Request Has an Empty Accept Header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/MISSING_HEADER_ACCEPT',\
ver:'OWASP_CRS/3.2.0',\
severity:'NOTICE',\
chain"
SecRule REQUEST_METHOD "!@rx ^OPTIONS$" \
"chain"
SecRule &REQUEST_HEADERS:User-Agent "@eq 0" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
#
# Empty User-Agent Header
#
# -=[ Rule Logic ]=-
# This rules will check to see if the User-Agent header is empty.
#
# Note that there is a second rule, 920320, which will check for
# the existence of the User-Agent header.
#
SecRule REQUEST_HEADERS:User-Agent "@rx ^$" \
"id:920330,\
phase:2,\
pass,\
t:none,\
msg:'Empty User Agent Header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/EMPTY_HEADER_UA',\
ver:'OWASP_CRS/3.2.0',\
severity:'NOTICE',\
setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
#
# Missing Content-Type Header with Request Body
#
# -=[ Rule Logic]=-
# This rule will first check to see if the value of the Content-Length header is
# non-equal to 0. The chained rule is then checking the existence of the
# Content-Type header. The RFCs do not state there must be a
# Content-Type header. However, a request missing a Content-Header is a
# strong indication of a non-compliant browser.
#
# Also, omitting the CT header allows to bypass the Request Body Processor
# unless you set the optional tx.enforce_bodyproc_urlencoded variable.
#
# Note: in default settings, this behavior only provides a NOTICE and will
# not cause a request to be blocked. However, in paranoia level 2 or
# higher, we run sibling 920341, which DOES block these requests.
#
# -=[ References ]=-
# http://httpwg.org/specs/rfc7231.html#header.content-type
SecRule REQUEST_HEADERS:Content-Length "!@rx ^0$" \
"id:920340,\
phase:2,\
pass,\
t:none,\
msg:'Request Containing Content, but Missing Content-Type header',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
ver:'OWASP_CRS/3.2.0',\
severity:'NOTICE',\
chain"
SecRule &REQUEST_HEADERS:Content-Type "@eq 0" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.notice_anomaly_score}'"
# Check that the host header is not an IP address
# This is not an HTTP RFC violation but it is indicative of automated client access.
# Many web-based worms propagate by scanning IP address blocks.
#
# -=[ Rule Logic ]=-
# This rule triggers if the Host header contains all digits (and possible port)
#
# -=[ References ]=-
# https://technet.microsoft.com/en-us/magazine/2005.01.hackerbasher.aspx
#
SecRule REQUEST_HEADERS:Host "@rx ^[\d.:]+$" \
"id:920350,\
phase:2,\
block,\
t:none,\
msg:'Host header is a numeric IP address',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/IP_HOST',\
tag:'WASCTC/WASC-21',\
tag:'OWASP_TOP_10/A7',\
tag:'PCI/6.5.10',\
ver:'OWASP_CRS/3.2.0',\
severity:'WARNING',\
setvar:'tx.anomaly_score_pl1=+%{tx.warning_anomaly_score}'"
# In most cases, you should expect a certain volume of each a request on your
# website. For example, a request with 400 arguments, can be suspicious.
# This file creates limitations on the request.
#
# TODO Look at the rules in this file, and define the sizes you'd like to enforce.
# Note that most of the rules are commented out by default.
# Uncomment the rules you need
#
#
# Maximum number of arguments in request limited
#
SecRule &TX:MAX_NUM_ARGS "@eq 1" \
"id:920380,\
phase:2,\
block,\
t:none,\
msg:'Too many arguments in request',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule &ARGS "@gt %{tx.max_num_args}" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
## -- Arguments limits --
#
# Limit argument name length
#
SecRule &TX:ARG_NAME_LENGTH "@eq 1" \
"id:920360,\
phase:2,\
block,\
t:none,\
msg:'Argument name too long',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule ARGS_NAMES "@gt %{tx.arg_name_length}" \
"t:none,t:length,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Limit argument value length
#
# This rule is also triggered by an Apache Struts Remote Code Execution exploit:
# [ Apache Struts vulnerability CVE-2017-9791 - Exploit tested: https://www.exploit-db.com/exploits/42324 ]
#
SecRule &TX:ARG_LENGTH "@eq 1" \
"id:920370,\
phase:2,\
block,\
t:none,\
msg:'Argument value too long',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule ARGS "@gt %{tx.arg_length}" \
"t:none,t:length,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Limit arguments total length
#
SecRule &TX:TOTAL_ARG_LENGTH "@eq 1" \
"id:920390,\
phase:2,\
block,\
t:none,\
msg:'Total arguments size exceeded',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule ARGS_COMBINED_SIZE "@gt %{tx.total_arg_length}" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# -- File upload limits --
#
# Individual file size is limited
SecRule &TX:MAX_FILE_SIZE "@eq 1" \
"id:920400,\
phase:2,\
block,\
t:none,\
msg:'Uploaded file size too large',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule REQUEST_HEADERS:Content-Type "@rx ^(?i)multipart/form-data" \
"chain"
SecRule REQUEST_HEADERS:Content-Length "@gt %{tx.max_file_size}" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Combined file size is limited
#
SecRule &TX:COMBINED_FILE_SIZES "@eq 1" \
"id:920410,\
phase:2,\
block,\
t:none,\
msg:'Total uploaded files size too large',\
logdata:'%{MATCHED_VAR_NAME}=%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/SIZE_LIMIT',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule FILES_COMBINED_SIZE "@gt %{tx.combined_file_sizes}" \
"t:none,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Restrict which content-types we accept.
#
# Restrict Content-Type header to established patterns.
#
# This provides generic whitelist protection against vulnerabilities like
# Apache Struts Content-Type arbitrary command execution (CVE-2017-5638).
#
# Examples of allowed patterns:
# - text/plain
# - text/plain; charset="UTF-8"
# - multipart/form-data; boundary=----WebKitFormBoundary12345
#
SecRule REQUEST_HEADERS:Content-Type "!@rx ^[\w\d/\.\-\+]+(?:\s?;\s?(?:boundary|charset)\s?=\s?['\"\w\d\.\-]+)?$" \
"id:920470,\
phase:1,\
block,\
t:none,t:lowercase,\
msg:'Illegal Content-Type header',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/CONTENT_TYPE',\
tag:'WASCTC/WASC-20',\
tag:'OWASP_TOP_10/A1',\
tag:'OWASP_AppSensor/EE2',\
tag:'PCI/12.1',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
# In case Content-Type header can be parsed, check the mime-type against
# the policy defined in the 'allowed_request_content_type' variable.
# To change your policy, edit crs-setup.conf and activate rule 900220.
SecRule REQUEST_HEADERS:Content-Type "@rx ^[^;\s]+" \
"id:920420,\
phase:2,\
block,\
capture,\
t:none,\
msg:'Request content type is not allowed by policy',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/CONTENT_TYPE_NOT_ALLOWED',\
tag:'WASCTC/WASC-20',\
tag:'OWASP_TOP_10/A1',\
tag:'OWASP_AppSensor/EE2',\
tag:'PCI/12.1',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule TX:0 "!@rx ^%{tx.allowed_request_content_type}$" \
"t:none,\
ctl:forceRequestBodyVariable=On,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Restrict charset parameter within the content-type header
#
SecRule REQUEST_HEADERS:Content-Type "@rx charset\s*=\s*([^;\s]+)" \
"id:920480,\
phase:1,\
block,\
capture,\
t:none,t:lowercase,\
msg:'Request content type charset is not allowed by policy',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/PROTOCOL_VIOLATION/CONTENT_TYPE_CHARSET',\
tag:'WASCTC/WASC-20',\
tag:'OWASP_TOP_10/A1',\
tag:'OWASP_AppSensor/EE2',\
tag:'PCI/12.1',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
chain"
SecRule TX:1 "!@rx ^%{tx.allowed_request_content_type_charset}$" \
"t:none,\
ctl:forceRequestBodyVariable=On,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Restrict protocol versions.
#
SecRule REQUEST_PROTOCOL "!@within %{tx.allowed_http_versions}" \
"id:920430,\
phase:1,\
block,\
t:none,\
msg:'HTTP protocol version is not allowed by policy',\
logdata:'%{MATCHED_VAR}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/PROTOCOL_NOT_ALLOWED',\
tag:'WASCTC/WASC-21',\
tag:'OWASP_TOP_10/A6',\
tag:'PCI/6.5.10',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"
#
# Restrict file extension
#
SecRule REQUEST_BASENAME "@rx \.([^.]+)$" \
"id:920440,\
phase:2,\
block,\
capture,\
t:none,\
msg:'URL file extension is restricted by policy',\
logdata:'%{TX.0}',\
tag:'application-multi',\
tag:'language-multi',\
tag:'platform-multi',\
tag:'attack-protocol',\
tag:'OWASP_CRS',\
tag:'OWASP_CRS/POLICY/EXT_RESTRICTED',\
tag:'WASCTC/WASC-15',\
tag:'OWASP_TOP_10/A7',\
tag:'PCI/6.5.10',\
ver:'OWASP_CRS/3.2.0',\
severity:'CRITICAL',\
setvar:'tx.extension=.%{tx.1}/',\
chain"
SecRule TX:EXTENSION "@within %{tx.restricted_extensions}" \
"t:none,t:urlDecodeUni,t:lowercase,\
setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"