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Apache httpd : Configure mod_security2022/03/16
 
Enable [mod_security] module to configure Web Application Firewall (WAF).
[1] Install [mod_security].
[root@www ~]#
dnf -y install mod_security
[2] After installing, configuration files are placed under the directory like follows and the setting is enabled. Some settings are already set in it and also you can add your own rules.
[root@www ~]#
cat /etc/httpd/conf.d/mod_security.conf 

<IfModule mod_security2.c>
    # Default recommended configuration
    SecRuleEngine On
    SecRequestBodyAccess On
    SecRule REQUEST_HEADERS:Content-Type "text/xml" \
         "id:'200000',phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=XML"
    SecRequestBodyLimit 13107200
    SecRequestBodyNoFilesLimit 131072
    SecRequestBodyInMemoryLimit 131072
    SecRequestBodyLimitAction Reject
    SecRule REQBODY_ERROR "!@eq 0" \
.....
.....
# if you would not like to block requests if matchs rules, # specify change to the parameter [SecRuleEngine DetectionOnly]
[3]
It's possible to write a rule like follows.
    ⇒ SecRule VARIABLES OPERATOR [ACTIONS]
Each parameter has many kind of values, refer to official documents below.
https://github.com/SpiderLabs/ModSecurity/wiki
[4] For Example, set some rules and verify it works normally.
[root@www ~]#
vi /etc/httpd/modsecurity.d/local_rules/modsecurity_localrules.conf
# default action when matching rules

SecDefaultAction "phase:2,deny,log,status:406"
# [etc/passwd] is included in request URI

SecRule REQUEST_URI "etc/passwd" "id:'500001'"
# [../] is included in request URI

SecRule REQUEST_URI "\.\./" "id:'500002'"
# [<SCRIPT] is included in arguments

SecRule ARGS "<[Ss][Cc][Rr][Ii][Pp][Tt]" "id:'500003'"
# [SELECT FROM] is included in arguments

SecRule ARGS "[Ss][Ee][Ll][Ee][Cc][Tt][[:space:]]+[Ff][Rr][Oo][Mm]" "id:'500004'"
[root@www ~]#
systemctl restart httpd
[5] Access to the URI which includes words you set and verify it works normally.
[6] The logs for [mod_security] is placed in the directory like follows.
[root@www ~]#
cat /var/log/httpd/modsec_audit.log 

.....
.....

--07b1e407-F--
HTTP/1.1 406 Not Acceptable
Content-Length: 249
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=iso-8859-1

--07b1e407-E--

--07b1e407-H--
Message: Access denied with code 406 (phase 2). Pattern match "<[Ss][Cc][Rr][Ii][Pp][Tt]" at ARGS:q. [file "/etc/httpd/modsecurity.d/local_rules/modsecurity_localrules.conf"] [line "15"] [id "500003"]
Apache-Error: [file "apache2_util.c"] [line 271] [level 3] [client 10.0.0.5] ModSecurity: Access denied with code 406 (phase 2). Pattern match "<[Ss][Cc][Rr][Ii][Pp][Tt]" at ARGS:q. [file "/etc/httpd/modsecurity.d/local_rules/modsecurity_localrules.conf"] [line "15"] [id "500003"] [hostname "www.srv.world"] [uri "/"] [unique_id "YjFJOpn4G-IerYngYR53lQAAAFU"]
Action: Intercepted (phase 2)
Stopwatch: 1647397178888826 797 (- - -)
Stopwatch2: 1647397178888826 797; combined=52, p1=18, p2=32, p3=0, p4=0, p5=2, sr=0, sw=0, l=0, gc=0
Response-Body-Transformed: Dechunked
Producer: ModSecurity for Apache/2.9.3 (http://www.modsecurity.org/).
Server: Apache
Engine-Mode: "ENABLED"

--07b1e407-Z--
[7] General rules are provided from official repository and it's easy to apply them like follows. But maybe you need to customize them for your own web sites not to block necessary requests.
[root@www ~]#
dnf -y install mod_security_crs
# rules are placed like follows
# they are linked into the directory [/etc/httpd/modsecurity.d/activated_rules]

[root@www ~]#
ll /usr/share/mod_modsecurity_crs/rules 

total 668
-rw-r--r--. 1 root root   786 Aug 10  2021 crawlers-user-agents.data
-rw-r--r--. 1 root root   551 Aug 10  2021 iis-errors.data
-rw-r--r--. 1 root root   933 Aug 10  2021 java-classes.data
-rw-r--r--. 1 root root   264 Aug 10  2021 java-code-leakages.data
-rw-r--r--. 1 root root   240 Aug 10  2021 java-errors.data
-rw-r--r--. 1 root root 31209 Aug 10  2021 lfi-os-files.data
-rw-r--r--. 1 root root  5409 Aug 10  2021 php-config-directives.data
-rw-r--r--. 1 root root  9201 Aug 10  2021 php-errors.data
-rw-r--r--. 1 root root   683 Aug 10  2021 php-function-names-933150.data
-rw-r--r--. 1 root root 21282 Aug 10  2021 php-function-names-933151.data
-rw-r--r--. 1 root root   224 Aug 10  2021 php-variables.data
-rw-r--r--. 1 root root 13513 Aug 10  2021 REQUEST-901-INITIALIZATION.conf
-rw-r--r--. 1 root root 13069 Aug 10  2021 REQUEST-903.9001-DRUPAL-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root 25812 Aug 10  2021 REQUEST-903.9002-WORDPRESS-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root 10642 Aug 10  2021 REQUEST-903.9003-NEXTCLOUD-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root  7822 Aug 10  2021 REQUEST-903.9004-DOKUWIKI-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root  1876 Aug 10  2021 REQUEST-903.9005-CPANEL-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root 18336 Aug 10  2021 REQUEST-903.9006-XENFORO-EXCLUSION-RULES.conf
-rw-r--r--. 1 root root  1555 Aug 10  2021 REQUEST-905-COMMON-EXCEPTIONS.conf
-rw-r--r--. 1 root root 10448 Aug 10  2021 REQUEST-910-IP-REPUTATION.conf
-rw-r--r--. 1 root root  2614 Aug 10  2021 REQUEST-911-METHOD-ENFORCEMENT.conf
-rw-r--r--. 1 root root 10743 Aug 10  2021 REQUEST-912-DOS-PROTECTION.conf
-rw-r--r--. 1 root root  7069 Aug 10  2021 REQUEST-913-SCANNER-DETECTION.conf
-rw-r--r--. 1 root root 50184 Aug 10  2021 REQUEST-920-PROTOCOL-ENFORCEMENT.conf
-rw-r--r--. 1 root root 13208 Aug 10  2021 REQUEST-921-PROTOCOL-ATTACK.conf
-rw-r--r--. 1 root root  5958 Aug 10  2021 REQUEST-930-APPLICATION-ATTACK-LFI.conf
-rw-r--r--. 1 root root  5678 Aug 10  2021 REQUEST-931-APPLICATION-ATTACK-RFI.conf
-rw-r--r--. 1 root root 54798 Aug 10  2021 REQUEST-932-APPLICATION-ATTACK-RCE.conf
-rw-r--r--. 1 root root 32617 Aug 10  2021 REQUEST-933-APPLICATION-ATTACK-PHP.conf
-rw-r--r--. 1 root root  3927 Aug 10  2021 REQUEST-934-APPLICATION-ATTACK-NODEJS.conf
-rw-r--r--. 1 root root 40398 Aug 10  2021 REQUEST-941-APPLICATION-ATTACK-XSS.conf
-rw-r--r--. 1 root root 70457 Aug 10  2021 REQUEST-942-APPLICATION-ATTACK-SQLI.conf
-rw-r--r--. 1 root root  5204 Aug 10  2021 REQUEST-943-APPLICATION-ATTACK-SESSION-FIXATION.conf
-rw-r--r--. 1 root root 15288 Aug 10  2021 REQUEST-944-APPLICATION-ATTACK-JAVA.conf
-rw-r--r--. 1 root root  4094 Aug 10  2021 REQUEST-949-BLOCKING-EVALUATION.conf
-rw-r--r--. 1 root root  4714 Aug 10  2021 RESPONSE-950-DATA-LEAKAGES.conf
-rw-r--r--. 1 root root 17863 Aug 10  2021 RESPONSE-951-DATA-LEAKAGES-SQL.conf
-rw-r--r--. 1 root root  3515 Aug 10  2021 RESPONSE-952-DATA-LEAKAGES-JAVA.conf
-rw-r--r--. 1 root root  4951 Aug 10  2021 RESPONSE-953-DATA-LEAKAGES-PHP.conf
-rw-r--r--. 1 root root  5764 Aug 10  2021 RESPONSE-954-DATA-LEAKAGES-IIS.conf
-rw-r--r--. 1 root root  4207 Aug 10  2021 RESPONSE-959-BLOCKING-EVALUATION.conf
-rw-r--r--. 1 root root  6801 Aug 10  2021 RESPONSE-980-CORRELATION.conf
-rw-r--r--. 1 root root  2043 Aug 10  2021 restricted-files.data
-rw-r--r--. 1 root root   390 Aug 10  2021 restricted-upload.data
-rw-r--r--. 1 root root   216 Aug 10  2021 scanners-headers.data
-rw-r--r--. 1 root root   418 Aug 10  2021 scanners-urls.data
-rw-r--r--. 1 root root  4869 Aug 10  2021 scanners-user-agents.data
-rw-r--r--. 1 root root   717 Aug 10  2021 scripting-user-agents.data
-rw-r--r--. 1 root root  1894 Aug 10  2021 sql-errors.data
-rw-r--r--. 1 root root  1380 Aug 10  2021 unix-shell.data
-rw-r--r--. 1 root root  3920 Aug 10  2021 windows-powershell-commands.data
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