ModSecurity OWASP核心規則集的兩種配置模式

本文主要介紹OWASP核心規則集的兩種配置模式。

OWASP規則的官方Github地址： https://github.com/coreruleset/coreruleset 。

OWASP V3版本核心規則集目前支持兩種配置模式：

異常評分模式（默認）和獨自控制模式

異常評分模式 ，也可稱爲”協同檢測模式”，在此模式下，當檢測到威脅時，並不會直接阻斷此次請求，而是向下繼續進行規則匹配，每個匹配成功的規則都會增加”異常分數”，在對請求數據檢測結束時，以及對返回數據檢測結束時，都會對異常分數的總和進行判斷，如果大於設置的閾值，纔會進行阻斷動作，並向客戶端返回403代碼，審計日誌中也會記錄此次訪問中所有匹配成功的規則信息。

獨自控制模式 ，此模式是V2版本規則集的默認模式，它的工作方式是，只要有一條規則匹配成功，便攔截此次訪問，審計日誌中也只會記錄第一次檢測到威脅的規則信息。

因此，通過上述描述我們可以簡單得出兩種模式的優缺點：

異常評分模式 ：由於每次請求都會匹配所有規則，因此在高併發情況下，效率相對較低，服務器資源佔用較高，但誤報率相對較低；

獨自控制模式 ：檢測到一次威脅就直接阻斷請求，因此在高併發情況下，效率相對較高，服務器資源佔用較小，但誤報率相對較高。除此之外該模式還有一個優點，即可以通過全局配置，設置當訪問被攔截後，跳轉到自定義的提示頁面。

如何配置跳轉到自定義提示頁面，可參見 http://modsecurity.cn/practice/post/8.html 。

在配置上，兩者配置區別如下（在crs-setup.conf中進行配置）：

異常評分模式 ：

SecDefaultAction "phase:1,log,auditlog,pass"
SecDefaultAction "phase:2,log,auditlog,pass"

由於是所有規則都進行匹配，因此SecDefaultAction並未使用”deny”關鍵詞，而是使用”pass”，即檢測到威脅後繼續下一規則的匹配。其中log代表記錄錯誤日誌，通常內容記錄在WEB服務的錯誤日誌文件中，auditlog代表記錄審計日誌，保存此次請求的詳細信息。如不需要記錄log或auditlog，直接刪除對應的關鍵詞即可。

獨自控制模式 ：

SecDefaultAction "phase:1,log,auditlog,deny,status:403"
SecDefaultAction "phase:2,log,auditlog,deny,status:403"

此配置表示，只要檢測到威脅，則使用”deny”關鍵詞對此次訪問進行阻斷，同時向服務器返回403錯誤代碼。

在審計日誌中，我們也能看到明顯的差異，比如模擬一次簡單的攻擊，如http://服務器IP/?param=%22%3E%3Cscript%3Ealert(1);%3C/script%3E，兩種模式所記錄的審計日誌如下（主要看日誌的H部分）：

異常評分模式下的審計日誌 ：

---5WCHvu3z---A--
[22/May/2020:17:16:14 +0800] 159013897435.560455 116.255.132.12 5289 172.21.0.15 80
---5WCHvu3z---B--
GET /?param=%22%3E%3Cscript%3Ealert(1);%3C/script%3E HTTP/1.1
Host: 49.233.80.239
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36
Cookie: memSize=1838
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9

---5WCHvu3z---D--

---5WCHvu3z---E--
<html>\x0d\x0a<head><title>403 Forbidden</title></head>\x0d\x0a<body>\x0d\x0a<center><h1>403 Forbidden</h1></center>\x0d\x0a<hr><center>nginx/1.16.1</center>\x0d\x0a</body>\x0d\x0a</html>\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a

---5WCHvu3z---F--
HTTP/1.1 403
Server: nginx/1.16.1
Date: Fri, 22 May 2020 09:16:14 GMT
Content-Length: 555
Content-Type: text/html
Connection: keep-alive

---5WCHvu3z---H--
ModSecurity: Warning. detected XSS using libinjection. [file "/usr/local/nginx/conf/modsecurity/rules/REQUEST-941-APPLICATION-ATTACK-XSS.conf"] [line "37"] [id "<b>941100</b>"] [rev ""] [msg "XSS Attack Detected via libinjection"] [data "Matched Data: XSS data found within ARGS:param: "><script>alert(1);</script>"] [severity "2"] [ver "OWASP_CRS/3.2.0"] [maturity "0"] [accuracy "0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-xss"] [tag "paranoia-level/1"] [tag "OWASP_CRS"] [tag "OWASP_CRS/WEB_ATTACK/XSS"] [tag "WASCTC/WASC-8"] [tag "WASCTC/WASC-22"] [tag "OWASP_TOP_10/A3"] [tag "OWASP_AppSensor/IE1"] [tag "CAPEC-242"] [hostname "172.21.0.15"] [uri "/"] [unique_id "159013897435.560455"] [ref "v12,28t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls"]

ModSecurity: Warning. Matched "Operator `Rx' with parameter `(?i)<script[^>]*>[\s\S]*?' against variable `ARGS:param' (Value: `"><script>alert(1);</script>' ) [file "/usr/local/nginx/conf/modsecurity/rules/REQUEST-941-APPLICATION-ATTACK-XSS.conf"] [line "68"] [id "<b>941110</b>"] [rev ""] [msg "XSS Filter - Category 1: Script Tag Vector"] [data "Matched Data: <script> found within ARGS:param: "><script>alert(1);</script>"] [severity "2"] [ver "OWASP_CRS/3.2.0"] [maturity "0"] [accuracy "0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-xss"] [tag "paranoia-level/1"] [tag "OWASP_CRS"] [tag "OWASP_CRS/WEB_ATTACK/XSS"] [tag "WASCTC/WASC-8"] [tag "WASCTC/WASC-22"] [tag "OWASP_TOP_10/A3"] [tag "OWASP_AppSensor/IE1"] [tag "CAPEC-242"] [hostname "172.21.0.15"] [uri "/"] [unique_id "159013897435.560455"] [ref "o2,8v12,28t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls"]

ModSecurity: Warning. Matched "Operator `Rx' with parameter `(?i:(?:<\w[\s\S]*[\s\/]|['\"](?:[\s\S]*[\s\/])?)(?:on(?:d(?:e(?:vice(?:(?:orienta|mo)tion|proximity|found|light)|livery(?:success|error)|activate)|r(?:ag(?:e(?:n(?:ter|d)|xit)|(?:gestur|leav)e|start|d (3146 characters omitted)' against variable `ARGS:param' (Value: `"><script>alert(1);</script>' ) [file "/usr/local/nginx/conf/modsecurity/rules/REQUEST-941-APPLICATION-ATTACK-XSS.conf"] [line "205"] [id "<b>941160</b>"] [rev ""] [msg "NoScript XSS InjectionChecker: HTML Injection"] [data "Matched Data: <script found within ARGS:param: "><script>alert(1);</script>"] [severity "2"] [ver "OWASP_CRS/3.2.0"] [maturity "0"] [accuracy "0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-xss"] [tag "paranoia-level/1"] [tag "OWASP_CRS"] [tag "OWASP_CRS/WEB_ATTACK/XSS"] [tag "WASCTC/WASC-8"] [tag "WASCTC/WASC-22"] [tag "OWASP_TOP_10/A3"] [tag "OWASP_AppSensor/IE1"] [tag "CAPEC-242"] [hostname "172.21.0.15"] [uri "/"] [unique_id "159013897435.560455"] [ref "o2,7o19,8v12,28t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls"]

ModSecurity: Access denied with code 403 (phase 2). Matched "Operator `Ge' with parameter `5' against variable `TX:ANOMALY_SCORE' (Value: `15' ) [file "/usr/local/nginx/conf/modsecurity/rules/REQUEST-949-BLOCKING-EVALUATION.conf"] [line "79"] [id "<b>949110</b>"] [rev ""] [msg "Inbound Anomaly Score Exceeded (Total Score: 15)"] [data ""] [severity "2"] [ver ""] [maturity "0"] [accuracy "0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-generic"] [hostname "172.21.0.15"] [uri "/"] [unique_id "159013897435.560455"] [ref ""]

上述審計日誌表示，此次訪問，分別觸發了ID爲941100、941110、941160三條規則，最終ID爲949110的規則對異常分數的總和進行判斷，發現大於設置的閾值，便執行阻斷操作，向客戶端返回403錯誤代碼，攔截此次訪問。

此次攔截在異常評分模式下涉及到的規則以及觸發流程如下：

首先，是REQUEST-901-INITIALIZATION.conf文件中的三條規則，ID分別爲901100、901120、901140，內容如下所示：

SecRule &TX:inbound_anomaly_score_threshold "@eq 0" \
    "id:901100,\
    phase:1,\
    pass,\
    nolog,\
    setvar:'tx.inbound_anomaly_score_threshold=5'"

SecRule &TX:paranoia_level "@eq 0" \
    "id:901120,\
    phase:1,\
    pass,\
    nolog,\
    setvar:'tx.paranoia_level=1'"

SecRule &TX:critical_anomaly_score "@eq 0" \
    "id:901140,\
    phase:1,\
    pass,\
    nolog,\
    setvar:'tx.critical_anomaly_score=5'"

此三條規則通過setvar關鍵字分別初始了三個變量的值，tx.inbound_anomaly_score_threshold爲5，tx.paranoia_level爲1，tx.critical_anomaly_score爲5，其中tx.inbound_anomaly_score_threshold爲最終判斷是否要阻斷此次請求的閾值。

然後，此次訪問分別觸發了REQUEST-941-APPLICATION-ATTACK-XSS.conf文件中的三條規則，ID分別爲941100、941110、941160，內容如下：

SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|REQUEST_HEADERS:User-Agent|ARGS_NAMES|ARGS|XML:/* "@detectXSS" \
    "id:941100,\
    phase:2,\
    block,\
    t:none,t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls,\
    msg:'XSS Attack Detected via libinjection',\
    logdata:'Matched Data: XSS data found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-xss',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'OWASP_CRS/WEB_ATTACK/XSS',\
    tag:'WASCTC/WASC-8',\
    tag:'WASCTC/WASC-22',\
    tag:'OWASP_TOP_10/A3',\
    tag:'OWASP_AppSensor/IE1',\
    tag:'CAPEC-242',\
    ctl:auditLogParts=+E,\
    ver:'OWASP_CRS/3.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.xss_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|REQUEST_FILENAME|REQUEST_HEADERS:User-Agent|REQUEST_HEADERS:Referer|ARGS_NAMES|ARGS|XML:/* "@rx (?i)<script[^>]*>[\s\S]*?" \
    "id:941110,\
    phase:2,\
    block,\
    capture,\
    t:none,t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls,\
    msg:'XSS Filter - Category 1: Script Tag Vector',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-xss',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'OWASP_CRS/WEB_ATTACK/XSS',\
    tag:'WASCTC/WASC-8',\
    tag:'WASCTC/WASC-22',\
    tag:'OWASP_TOP_10/A3',\
    tag:'OWASP_AppSensor/IE1',\
    tag:'CAPEC-242',\
    ctl:auditLogParts=+E,\
    ver:'OWASP_CRS/3.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.xss_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

SecRule REQUEST_COOKIES|!REQUEST_COOKIES:/__utm/|REQUEST_COOKIES_NAMES|REQUEST_HEADERS:User-Agent|REQUEST_HEADERS:Referer|ARGS_NAMES|ARGS|XML:/* "@rx (?i:(?:<\w[\s\S]*[\s\/]|['\"](?:[\s\S]*[\s\/])?)(?:on(?:d(?:e(?:vice(?:(?:orienta|mo)tion|proximity|found|light)|livery(?:success|error)|activate)|r(?:ag(?:e(?:n(?:ter|d)|xit)|(?:gestur|leav)e|start|drop|over)|op)|i(?:s(?:c(?:hargingtimechange|onnect(?:ing|ed))|abled)|aling)|ata(?:setc(?:omplete|hanged)|(?:availabl|chang)e|error)|urationchange|ownloading|blclick)|Moz(?:M(?:agnifyGesture(?:Update|Start)?|ouse(?:PixelScroll|Hittest))|S(?:wipeGesture(?:Update|Start|End)?|crolledAreaChanged)|(?:(?:Press)?TapGestur|BeforeResiz)e|EdgeUI(?:C(?:omplet|ancel)|Start)ed|RotateGesture(?:Update|Start)?|A(?:udioAvailable|fterPaint))|c(?:o(?:m(?:p(?:osition(?:update|start|end)|lete)|mand(?:update)?)|n(?:t(?:rolselect|extmenu)|nect(?:ing|ed))|py)|a(?:(?:llschang|ch)ed|nplay(?:through)?|rdstatechange)|h(?:(?:arging(?:time)?ch)?ange|ecking)|(?:fstate|ell)change|u(?:echange|t)|l(?:ick|ose))|s(?:t(?:a(?:t(?:uschanged|echange)|lled|rt)|k(?:sessione|comma)nd|op)|e(?:ek(?:complete|ing|ed)|(?:lec(?:tstar)?)?t|n(?:ding|t))|(?:peech|ound)(?:start|end)|u(?:ccess|spend|bmit)|croll|how)|m(?:o(?:z(?:(?:pointerlock|fullscreen)(?:change|error)|(?:orientation|time)change|network(?:down|up)load)|use(?:(?:lea|mo)ve|o(?:ver|ut)|enter|wheel|down|up)|ve(?:start|end)?)|essage|ark)|a(?:n(?:imation(?:iteration|start|end)|tennastatechange)|fter(?:(?:scriptexecu|upda)te|print)|udio(?:process|start|end)|d(?:apteradded|dtrack)|ctivate|lerting|bort)|b(?:e(?:fore(?:(?:(?:de)?activa|scriptexecu)te|u(?:nload|pdate)|p(?:aste|rint)|c(?:opy|ut)|editfocus)|gin(?:Event)?)|oun(?:dary|ce)|l(?:ocked|ur)|roadcast|usy)|DOM(?:Node(?:Inserted(?:IntoDocument)?|Removed(?:FromDocument)?)|(?:CharacterData|Subtree)Modified|A(?:ttrModified|ctivate)|Focus(?:Out|In)|MouseScroll)|r(?:e(?:s(?:u(?:m(?:ing|e)|lt)|ize|et)|adystatechange|pea(?:tEven)?t|movetrack|trieving|ceived)|ow(?:s(?:inserted|delete)|e(?:nter|xit))|atechange)|p(?:op(?:up(?:hid(?:den|ing)|show(?:ing|n))|state)|a(?:ge(?:hide|show)|(?:st|us)e|int)|ro(?:pertychange|gress)|lay(?:ing)?)|t(?:ouch(?:(?:lea|mo)ve|en(?:ter|d)|cancel|start)|ransition(?:cancel|end|run)|ime(?:update|out)|ext)|u(?:s(?:erproximity|sdreceived)|p(?:gradeneeded|dateready)|n(?:derflow|load))|f(?:o(?:rm(?:change|input)|cus(?:out|in)?)|i(?:lterchange|nish)|ailed)|l(?:o(?:ad(?:e(?:d(?:meta)?data|nd)|start)|secapture)|evelchange|y)|g(?:amepad(?:(?:dis)?connected|button(?:down|up)|axismove)|et)|e(?:n(?:d(?:Event|ed)?|abled|ter)|rror(?:update)?|mptied|xit)|i(?:cc(?:cardlockerror|infochange)|n(?:coming|valid|put))|o(?:(?:(?:ff|n)lin|bsolet)e|verflow(?:changed)?|pen)|SVG(?:(?:Unl|L)oad|Resize|Scroll|Abort|Error|Zoom)|h(?:e(?:adphoneschange|l[dp])|ashchange|olding)|v(?:o(?:lum|ic)e|ersion)change|w(?:a(?:it|rn)ing|heel)|key(?:press|down|up)|(?:AppComman|Loa)d|no(?:update|match)|Request|zoom)|s(?:tyle|rc)|background|formaction|lowsrc|ping)[\s\x08]*?=|<[^\w<>]*(?:[^<>\"'\s]*:)?[^\w<>]*\W*?(?:(?:a\W*?(?:n\W*?i\W*?m\W*?a\W*?t\W*?e|p\W*?p\W*?l\W*?e\W*?t|u\W*?d\W*?i\W*?o)|b\W*?(?:i\W*?n\W*?d\W*?i\W*?n\W*?g\W*?s|a\W*?s\W*?e|o\W*?d\W*?y)|i?\W*?f\W*?r\W*?a\W*?m\W*?e|o\W*?b\W*?j\W*?e\W*?c\W*?t|i\W*?m\W*?a?\W*?g\W*?e?|e\W*?m\W*?b\W*?e\W*?d|p\W*?a\W*?r\W*?a\W*?m|v\W*?i\W*?d\W*?e\W*?o|l\W*?i\W*?n\W*?k)[^>\w]|s\W*?(?:c\W*?r\W*?i\W*?p\W*?t|t\W*?y\W*?l\W*?e|e\W*?t[^>\w]|v\W*?g)|m\W*?(?:a\W*?r\W*?q\W*?u\W*?e\W*?e|e\W*?t\W*?a[^>\w])|f\W*?o\W*?r\W*?m))" \
    "id:941160,\
    phase:2,\
    block,\
    capture,\
    t:none,t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls,\
    msg:'NoScript XSS InjectionChecker: HTML Injection',\
    logdata:'Matched Data: %{TX.0} found within %{MATCHED_VAR_NAME}: %{MATCHED_VAR}',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-xss',\
    tag:'paranoia-level/1',\
    tag:'OWASP_CRS',\
    tag:'OWASP_CRS/WEB_ATTACK/XSS',\
    tag:'WASCTC/WASC-8',\
    tag:'WASCTC/WASC-22',\
    tag:'OWASP_TOP_10/A3',\
    tag:'OWASP_AppSensor/IE1',\
    tag:'CAPEC-242',\
    ctl:auditLogParts=+E,\
    ver:'OWASP_CRS/3.2.0',\
    severity:'CRITICAL',\
    setvar:'tx.xss_score=+%{tx.critical_anomaly_score}',\
    setvar:'tx.anomaly_score_pl1=+%{tx.critical_anomaly_score}'"

三條規則中，每次都會通過setvar關鍵詞，將tx.anomaly_score_pl1變量的值加5，即+%{tx.critical_anomaly_score}，%{}代表獲取變量的值。由於匹配了三次，因此此時tx.anomaly_score_pl1的值變成了15。

接下來，REQUEST-949-BLOCKING-EVALUATION.conf文件中的兩條規則被執行，ID分別爲949060、949110，規則內容如下：

SecRule TX:PARANOIA_LEVEL "@ge 1" \
    "id:949060,\
    phase:2,\
    pass,\
    t:none,\
    nolog,\
    setvar:'tx.anomaly_score=+%{tx.anomaly_score_pl1}'"

SecRule TX:ANOMALY_SCORE "@ge %{tx.inbound_anomaly_score_threshold}" \
    "id:949110,\
    phase:2,\
    deny,\
    t:none,\
    log,\
    msg:'Inbound Anomaly Score Exceeded (Total Score: %{TX.ANOMALY_SCORE})',\
    tag:'application-multi',\
    tag:'language-multi',\
    tag:'platform-multi',\
    tag:'attack-generic',\
    severity:'CRITICAL',\
    setvar:'tx.inbound_anomaly_score=%{tx.anomaly_score}'"

ID爲949060的規則表示，當tx.paranoia_level的值爲1時，創建變量tx.anomaly_score，同時賦予tx.anomaly_score_pl1變量的值，此時tx.anomaly_score的值也成爲了15，然後，ID爲949110的規則對tx.anomaly_score變量進行判斷，如果大於tx.inbound_anomaly_score_threshold變量的值，則通過deny關鍵詞進行阻斷，而tx.inbound_anomaly_score_threshold變量初始值爲5，15>5，tx.anomaly_score>tx.inbound_anomaly_score_threshold，條件匹配成功，此次訪問被阻斷。當然，實際參與此次訪問判斷的規則並非只有上述規則，本人只是將涉及到此次攔截的規則單獨摘取出來，進行攔截流程的簡要介紹。

獨自控制模式下的審計日誌：

---AHNuWePS---A--
[22/May/2020:17:13:41 +0800] 159013882129.161492 116.255.132.12 55959 172.21.0.15 80
---AHNuWePS---B--
GET /?param=%22%3E%3Cscript%3Ealert(1);%3C/script%3E HTTP/1.1
Host: 49.233.80.239
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36
Cookie: memSize=1838
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9

---AHNuWePS---D--

---AHNuWePS---E--
<html>\x0d\x0a<head><title>403 Forbidden</title></head>\x0d\x0a<body>\x0d\x0a<center><h1>403 Forbidden</h1></center>\x0d\x0a<hr><center>nginx/1.16.1</center>\x0d\x0a</body>\x0d\x0a</html>\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a<!-- a padding to disable MSIE and Chrome friendly error page -->\x0d\x0a

---AHNuWePS---F--
HTTP/1.1 403
Server: nginx/1.16.1
Date: Fri, 22 May 2020 09:13:41 GMT
Content-Length: 555
Content-Type: text/html
Connection: keep-alive

---AHNuWePS---H--
ModSecurity: Access denied with code 403 (phase 2). detected XSS using libinjection. [file "/usr/local/nginx/conf/modsecurity/rules/REQUEST-941-APPLICATION-ATTACK-XSS.conf"] [line "37"] [id "941100"] [rev ""] [msg "XSS Attack Detected via libinjection"] [data "Matched Data: XSS data found within ARGS:param: "><script>alert(1);</script>"] [severity "2"] [ver "OWASP_CRS/3.2.0"] [maturity "0"] [accuracy "0"] [tag "application-multi"] [tag "language-multi"] [tag "platform-multi"] [tag "attack-xss"] [tag "paranoia-level/1"] [tag "OWASP_CRS"] [tag "OWASP_CRS/WEB_ATTACK/XSS"] [tag "WASCTC/WASC-8"] [tag "WASCTC/WASC-22"] [tag "OWASP_TOP_10/A3"] [tag "OWASP_AppSensor/IE1"] [tag "CAPEC-242"] [hostname "172.21.0.15"] [uri "/"] [unique_id "159013882129.161492"] [ref "v12,28t:utf8toUnicode,t:urlDecodeUni,t:htmlEntityDecode,t:jsDecode,t:cssDecode,t:removeNulls"]

上述部分已經闡述，獨自控制模式是隻要檢測到一次威脅就直接攔截此次請求，因此日誌顯示僅觸發了ID爲941100的規則。

除此之外，通過DEBUG日誌分析，兩種模式下所進行的規則匹配次數也不相同。由於DEBUG日誌內容過多，因此此處不進行日誌內容展示，僅展示最終數據。

當通過訪問http://服務器IP/?param=%22%3E%3Cscript%3Ealert(1);%3C/script%3E進行模擬攻擊時：

異常評分模式下，包含初始化配置類等相關規則，共有340條規則被執行；

獨自控制模式下，包含初始化配置類等相關規則，共有282條規則被執行。

目前本人所使用的模式爲獨自控制模式。

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