# ------------------------------------------------------------------------
# OWASP CRS ver.4.2.0
# Copyright (c) 2006-2020 Trustwave and contributors. All rights reserved.
# Copyright (c) 2021-2024 CRS project. All rights reserved.
#
# The OWASP CRS is distributed under
# Apache Software License (ASL) version 2
# Please see the enclosed LICENSE file for full details.
# ------------------------------------------------------------------------

#
# -= Paranoia Level 0 (empty) =- (apply unconditionally)
#



SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 1" "id:921011,phase:1,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 1" "id:921012,phase:2,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
#
# -= Paranoia Level 1 (default) =- (apply only when tx.detection_paranoia_level is sufficiently high: 1 or higher)
#

#
# -=[ HTTP Request Smuggling ]=-
#
# [ Rule Logic ]
# This rule looks for a HTTP / WEBDAV method name in combination with the word http/\d or a CR/LF character.
# This would point to an attempt to inject a 2nd request into the request, thus bypassing
# tests carried out on the primary request.
#
# [ References ]
# http://projects.webappsec.org/HTTP-Request-Smuggling
#
SecRule ARGS_NAMES|ARGS|REQUEST_BODY|XML:/* "@rx (?:get|post|head|options|connect|put|delete|trace|track|patch|propfind|propatch|mkcol|copy|move|lock|unlock)\s+[^\s]+\s+http/\d" \
    "id:921110,\
    phase:2,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,t:lowercase,\
    msg:'HTTP Request Smuggling Attack',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/33',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

#
# -=[ HTTP Response Splitting ]=-
#
# [ Rule Logic ]
# These rules look for Carriage Return (CR) %0d and Linefeed (LF) %0a characters.
# These characters may cause problems if the data is returned in a response header and
# may be interpreted by an intermediary proxy server and treated as two separate
# responses.
#
# [ References ]
# http://projects.webappsec.org/HTTP-Response-Splitting
#
SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|ARGS_NAMES|ARGS|XML:/* "@rx [\r\n]\W*?(?:content-(?:type|length)|set-cookie|location):\s*\w" \
    "id:921120,\
    phase:2,\
    block,\
    capture,\
    t:none,t:lowercase,\
    msg:'HTTP Response Splitting Attack',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/34',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|ARGS_NAMES|ARGS|XML:/* "@rx (?:\bhttp/\d|<(?:html|meta)\b)" \
    "id:921130,\
    phase:2,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,t:lowercase,\
    msg:'HTTP Response Splitting Attack',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/34',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

#
# -=[ HTTP Header Injection ]=-
#
# [ Rule Logic ]
# These rules look for Carriage Return (CR) %0d and Linefeed (LF) %0a characters,
# on their own or in combination with header field names.
# These characters may cause problems if the data is returned in a response header
# and interpreted by the client.
# The rules are similar to rules defending against the HTTP Request Splitting and
# Request Smuggling rules.
#
# [ References ]
# https://en.wikipedia.org/wiki/HTTP_header_injection
#
SecRule REQUEST_HEADERS_NAMES|REQUEST_HEADERS "@rx [\n\r]" \
    "id:921140,\
    phase:1,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,\
    msg:'HTTP Header Injection Attack via headers',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/273',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


# Detect newlines in argument names.
# Checking for GET arguments has been moved to paranoia level 2 (921151)
# in order to mitigate possible false positives.
#
# This rule is also triggered by the following exploit(s):
# [ SAP CRM Java vulnerability CVE-2018-2380 - Exploit tested: https://www.exploit-db.com/exploits/44292 ]
#
SecRule ARGS_NAMES "@rx [\n\r]" \
    "id:921150,\
    phase:2,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,\
    msg:'HTTP Header Injection Attack via payload (CR/LF detected)',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/33',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


SecRule ARGS_GET_NAMES|ARGS_GET "@rx [\n\r]+(?:\s|location|refresh|(?:set-)?cookie|(?:x-)?(?:forwarded-(?:for|host|server)|host|via|remote-ip|remote-addr|originating-IP))\s*:" \
    "id:921160,\
    phase:1,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,t:lowercase,\
    msg:'HTTP Header Injection Attack via payload (CR/LF and header-name detected)',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/33',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


# -=[ HTTP Splitting ]=-
#
# This rule detect \n or \r in the REQUEST FILENAME
# Reference: https://wiki.owasp.org/index.php/Testing_for_HTTP_Splitting/Smuggling_(OTG-INPVAL-016)
# Reference: https://owasp.org/www-project-web-security-testing-guide/assets/archive/OWASP_Testing_Guide_v4.pdf
#
SecRule REQUEST_FILENAME "@rx [\n\r]" \
    "id:921190,\
    phase:1,\
    block,\
    t:none,t:urlDecodeUni,\
    msg:'HTTP Splitting (CR/LF in request filename detected)',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/34',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


#
# -=[ LDAP Injection ]=-
#
# [ Rule Logic ]
#
# This is a rule trying to prevent LDAP injection. It is based on a BlackHat presentation by Alonso Parada
# and regex writing by Denis Kolegov.
#
# [ References ]
# * https://www.blackhat.com/presentations/bh-europe-08/Alonso-Parada/Whitepaper/bh-eu-08-alonso-parada-WP.pdf
# * https://www.sonarsource.com/blog/joomla-takeover-in-20-seconds-with-ldap-injection-cve-2017-14596/
# * https://github.com/SpiderLabs/owasp-modsecurity-crs/issues/276#issue-126581660

SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|ARGS_NAMES|ARGS|XML:/* "@rx ^[^:\(\)\&\|\!\<\>\~]*\)\s*(?:\((?:[^,\(\)\=\&\|\!\<\>\~]+[><~]?=|\s*[&!|]\s*(?:\)|\()?\s*)|\)\s*\(\s*[\&\|\!]\s*|[&!|]\s*\([^\(\)\=\&\|\!\<\>\~]+[><~]?=[^:\(\)\&\|\!\<\>\~]*)" \
    "id:921200,\
    phase:2,\
    block,\
    capture,\
    t:none,t:htmlEntityDecode,\
    msg:'LDAP Injection Attack',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-ldap',\
    tag:'platform-multi',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/152/248/136',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

#
# -=[ Body Processor Bypass ]=-
#
# [ Rule Logic ]
#
# This rule intends to detect content types in the Content-Type header outside of the actual content type declaration.
# This prevents bypasses targeting the Modsecurity recommended rules controlling which body processor is used.
#
# Regular expression generated from regex-assembly/921421.ra.
# To update the regular expression run the following shell script
# (consult https://coreruleset.org/docs/development/regex_assembly/ for details):
#   crs-toolchain regex update 921421
#
SecRule REQUEST_HEADERS:Content-Type "@rx ^[^\s\x0b,;]+[\s\x0b,;].*?(?:application/(?:.+\+)?json|(?:application/(?:soap\+)?|text/)xml)" \
    "id:921421,\
    phase:1,\
    block,\
    capture,\
    t:none,t:lowercase,\
    msg:'Content-Type header: Dangerous content type outside the mime type declaration',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/255/153',\
    tag:'PCI/12.1',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


#
# Rule against CVE-2021-40438:
# A crafted request uri-path can cause mod_proxy to forward the request to an origin server choosen by the remote user.
# This issue affects Apache HTTP Server 2.4.48 and earlier.
# GET /?unix:AAAAAAAAAAAAA|http://coreruleset.org/
#
SecRule REQUEST_URI "@rx unix:[^|]*\|" \
    "id:921240,\
    phase:1,\
    block,\
    capture,\
    t:none,t:urlDecode,t:lowercase,\
    msg:'mod_proxy attack attempt detected',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-apache',\
    tag:'attack-protocol',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/33',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score_pl1=+%{tx.critical_anomaly_score}'"


SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 2" "id:921013,phase:1,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 2" "id:921014,phase:2,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
#
# -= Paranoia Level 2 =- (apply only when tx.detection_paranoia_level is sufficiently high: 2 or higher)
#


# Detect newlines in GET argument values.
# These may point to a HTTP header injection attack, but can also sometimes
# occur in benign query parameters.
#
# See also: rule 921140, 921150
#
SecRule ARGS_GET "@rx [\n\r]" \
    "id:921151,\
    phase:1,\
    block,\
    capture,\
    t:none,t:urlDecodeUni,t:htmlEntityDecode,\
    msg:'HTTP Header Injection Attack via payload (CR/LF detected)',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/2',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220/33',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl2=+%{tx.critical_anomaly_score}'"

#
# -=[ Body Processor Bypass ]=-
#
# [ Rule Logic ]
#
# This rule intends to detect content types in the Content-Type header outside of the actual content type declaration.
#
# [ References ]
# * See rule 921422
#
# Regular expression generated from regex-assembly/921422.ra.
# To update the regular expression run the following shell script
# (consult https://coreruleset.org/docs/development/regex_assembly/ for details):
#   crs-toolchain regex update 921422
#
SecRule REQUEST_HEADERS:Content-Type "@rx ^[^\s\x0b,;]+[\s\x0b,;].*?\b(?:((?:tex|multipar)t|application)|((?:audi|vide)o|image|cs[sv]|(?:vn|relate)d|p(?:df|lain)|json|(?:soa|cs)p|x(?:ml|-www-form-urlencoded)|form-data|x-amf|(?:octe|repor)t|stream)|([\+/]))\b" \
    "id:921422,\
    phase:1,\
    block,\
    capture,\
    t:none,t:lowercase,\
    msg:'Content-Type header: Dangerous content type outside the mime type declaration',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/2',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/255/153',\
    tag:'PCI/12.1',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score_pl2=+%{tx.critical_anomaly_score}'"


SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 3" "id:921015,phase:1,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 3" "id:921016,phase:2,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
#
# -= Paranoia Level 3 =- (apply only when tx.detection_paranoia_level is sufficiently high: 3 or higher)
#
#

# Forbid Request Range Header
#
# It is possible abuse the HTTP Request Range Header to leak error pages
# and other information in very small snippets.
# The easiest way to fight this is to deny the use of this header.
# This is a viable option since the header is only used in rare circumstances
# anymore.
# If it is necessary to use it in a certain setup, then it is best to
# create a rule exclusion for a given URI and this rule ID as a workaround.
#
SecRule &REQUEST_HEADERS:Range "@gt 0" \
    "id:921230,\
    phase:1,\
    block,\
    t:none,\
    msg:'HTTP Range Header detected',\
    logdata:'Matched Data: Header %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/3',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/210/272/220',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score_pl3=+%{tx.critical_anomaly_score}'"


# -=[ HTTP Parameter Pollution ]=-
#
# [ Rule Logic ]
# These rules look for multiple parameters with the same name.
# 921170 counts the occurrences of the individual parameters.
# 921180 checks if any counter is > 1.
#
# One HPP attack vector is to try evade signature filters by distributing the
# attack payload across multiple parameters with the same name.
# This works as many security devices only apply signatures to individual
# parameter payloads, however the back-end web application may (in the case
# of ASP.NET) consolidate all of the payloads into one thus making the
# attack payload active.
#
# [ References ]
# http://tacticalwebappsec.blogspot.com/2009/05/http-parameter-pollution.html
# https://capec.mitre.org/data/definitions/460.html
#
SecRule ARGS_NAMES "@rx ." \
    "id:921170,\
    phase:2,\
    pass,\
    nolog,\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/152/137/15/460',\
    ver:'OWASP_CRS/4.2.0',\
    setvar:'TX.paramcounter_%{MATCHED_VAR_NAME}=+1'"

SecRule TX:/paramcounter_.*/ "@gt 1" \
    "id:921180,\
    phase:2,\
    pass,\
    msg:'HTTP Parameter Pollution (%{TX.1})',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/3',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/152/137/15/460',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    chain"
    SecRule MATCHED_VARS_NAMES "@rx TX:paramcounter_(.*)" \
        "capture,\
        setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
        setvar:'tx.inbound_anomaly_score_pl3=+%{tx.critical_anomaly_score}'"


# -=[ HTTP Parameter Pollution ]=-
#
# [ Rule Logic ]
# Parameter pollution rule 921180 PL3 can by bypassed when a weak backend parameter
# parser is ignoring additional characters in a parameter array name after the
# closing of the array.
# Rule 921210 PL3 prevents this by disallowing arbitrary strings after an array has
# been closed or inbetween the square brackets in multidimensional arrays.
# Please note that rule 921210 allows for 2-dimensional, but not for higher dimensional
# arrays. If these are flagged as attacks, a rule exclusion will have to be
# deployed; ideally for the parameter(s) in question.
#
# [ References ]
# Private bug bounty in Spring 2022, findings Z05OZUCH.
#
# [ Payloads ]
# * foo[1]a=bar&foo[1]b=<evil> - parameter parsers often cut after the closing of
#   the array. 921180 PL3 takes the full name, though.
#   This impediance mismatch allows for bypasses.
# * foo[1]x[1]=bar&foo[1]x[2]=<evil> - extension of 1; this has the advantage that
#   the parameter name does end with "]" just like a valid array notation.
#
SecRule ARGS_NAMES "@rx (][^\]]+$|][^\]]+\[)" \
    "id:921210,\
    phase:2,\
    pass,\
    log,\
    msg:'HTTP Parameter Pollution after detecting bogus char after parameter array',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/3',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/152/137/15/460',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl3=+%{tx.critical_anomaly_score}'"



SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 4" "id:921017,phase:1,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
SecRule TX:DETECTION_PARANOIA_LEVEL "@lt 4" "id:921018,phase:2,pass,nolog,tag:'OWASP_CRS',ver:'OWASP_CRS/4.2.0',skipAfter:END-REQUEST-921-PROTOCOL-ATTACK"
#
# -= Paranoia Level 4 =- (apply only when tx.detection_paranoia_level is sufficiently high: 4 or higher)
#

# -=[ HTTP Parameter Pollution ]=-
#
# [ Rule Logic ]
# Parameter pollution rule 921180 PL3 and 921210 PL3 can by bypassed if a
# weak backend parameter parser ignores parameter array alltogether at
# cuts parameter names at the first occurrence of the "[" character.
# The rule 921220 PL4 prevents this by disallowing parameter array names.
#
# If an application needs parameter array names, then this rule should be
# disabled, ideally by issueing a rule exclusion for the parameter names
# that need it.
#
# [ References ]
# Private bug bounty in Spring 2022, finding 5UXE4RK0.
#
# [ Payloads ]
# * foo[1]=bar&foo[2]=<evil>
# * foo=bar&foo[1]=<evil>
# * foo[1]=bar&foo[1]acb]=<evil> - this is an edge case that 921210 PL3 is not
#   able to catch since the parameter name ends with "]".
#
SecRule ARGS_NAMES "@rx \[" \
    "id:921220,\
    phase:2,\
    pass,\
    log,\
    msg:'HTTP Parameter Pollution possible via array notation',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-protocol',\
    tag:'paranoia-level/4',\
    tag:'OWASP_CRS',\
    tag:'capec/1000/152/137/15/460',\
    ver:'OWASP_CRS/4.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.http_violation_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.inbound_anomaly_score_pl4=+%{tx.critical_anomaly_score}'"



#
# -= Paranoia Levels Finished =-
#
SecMarker "END-REQUEST-921-PROTOCOL-ATTACK"
