我下定决心，安装了 mod_security 来保护我们的 WHMCS 安装（基于 PHP 的计费系统）免受一些更明显的 SQL 注入攻击，并尽量减少我们在漏洞被人知晓和我们发现漏洞之间的机会窗口内受到攻击的可能性（此时我们会根据需要部署 IP ACL 或新的 mod_security 规则，并在修复程序可用时进行修补）
问题是，我从 WHT 中学到了一些规则，这些规则在纸面上看起来不错，但当我测试它们时，mod_security出现正在执行其操作 - 恶意客户端被转移到 403，但由于数据库内容正在发生变化，POST 数据似乎仍能到达 PHP 脚本。
PHP 正在使用 suPHP 运行；从谷歌搜索中我无法确定这是否是导致问题的可能原因——我无法想象这是一种不常见的配置。
在我看来，可能的原因是，尽管 mod_security 被设置为拒绝，它仍然会生成中间响应主体（从它可以记录它的事实可以看出，在类型 E 下）——这当然涉及到提交我想首先停止提交的数据！然而，即使我将 SecResponseBodyAccess 设置为 Off，它也不会停止提交数据——说实话，我不会不合理地期望在请求阶段触发的拒绝/删除规则会阻止任何生成响应主体的尝试。
有谁能解释一下这个问题？这个版本的 mod_security 中是否存在错误（我似乎不太可能第一个注意到），我选择的规则是否有缺陷（可能），或者我的配置中是否存在愚蠢的错误（最有可能）？
这是一个 Debian Squeeze 系统；可能相关的软件包：
ii apache2 2.2.16-6+squeeze11 Apache HTTP Server metapackage
ii libapache2-mod-suphp 0.7.1-1 Apache2 module to run php scripts with the owner permissions
ii libapache2-modsecurity 2.6.6-6~bpo60+1 Tighten web applications security for Apache
/etc/apache2/mods-enabled/modsecurity.load
LoadFile /usr/lib/libxml2.so.2
LoadModule security2_module /usr/lib/apache2/modules/mod_security2.so
/etc/apache2/mods-enabled/modsecurity.conf
<IfModule security2_module>
# Default Debian dir for modsecurity's persistent data
SecDataDir /var/cache/modsecurity
# Include all the *.conf files in /etc/modsecurity.
# Keeping your local configuration in that directory
# will allow for an easy upgrade of THIS file and
# make your life easier
Include "/etc/modsecurity/*.conf"
</IfModule>
/etc/modsecurity/modsecurity.conf （与 Debian 默认推荐配置相比，基本没有变化 - 除了将 SecRuleEngine DetectionOnly 更改为 On）
# -- Rule engine initialization ----------------------------------------------
# Enable ModSecurity, attaching it to every transaction. Use detection
# only to start with, because that minimises the chances of post-installation
# disruption.
#
SecRuleEngine On
# -- Request body handling ---------------------------------------------------
# Allow ModSecurity to access request bodies. If you don't, ModSecurity
# won't be able to see any POST parameters, which opens a large security
# hole for attackers to exploit.
#
SecRequestBodyAccess On
# Enable XML request body parser.
# Initiate XML Processor in case of xml content-type
#
SecRule REQUEST_HEADERS:Content-Type "text/xml" \
"phase:1,t:none,t:lowercase,pass,nolog,ctl:requestBodyProcessor=XML"
# Maximum request body size we will accept for buffering. If you support
# file uploads then the value given on the first line has to be as large
# as the largest file you are willing to accept. The second value refers
# to the size of data, with files excluded. You want to keep that value as
# low as practical.
#
SecRequestBodyLimit 13107200
SecRequestBodyNoFilesLimit 131072
# Store up to 128 KB of request body data in memory. When the multipart
# parser reachers this limit, it will start using your hard disk for
# storage. That is slow, but unavoidable.
#
SecRequestBodyInMemoryLimit 131072
# What do do if the request body size is above our configured limit.
# Keep in mind that this setting will automatically be set to ProcessPartial
# when SecRuleEngine is set to DetectionOnly mode in order to minimize
# disruptions when initially deploying ModSecurity.
#
SecRequestBodyLimitAction Reject
# Verify that we've correctly processed the request body.
# As a rule of thumb, when failing to process a request body
# you should reject the request (when deployed in blocking mode)
# or log a high-severity alert (when deployed in detection-only mode).
#
SecRule REQBODY_ERROR "!@eq 0" \
"phase:2,t:none,log,deny,status:400,msg:'Failed to parse request body.',logdata:'%{reqbody_error_msg}',severity:2"
# By default be strict with what we accept in the multipart/form-data
# request body. If the rule below proves to be too strict for your
# environment consider changing it to detection-only. You are encouraged
# _not_ to remove it altogether.
#
SecRule MULTIPART_STRICT_ERROR "!@eq 0" \
"phase:2,t:none,log,deny,status:44,msg:'Multipart request body \
failed strict validation: \
PE %{REQBODY_PROCESSOR_ERROR}, \
BQ %{MULTIPART_BOUNDARY_QUOTED}, \
BW %{MULTIPART_BOUNDARY_WHITESPACE}, \
DB %{MULTIPART_DATA_BEFORE}, \
DA %{MULTIPART_DATA_AFTER}, \
HF %{MULTIPART_HEADER_FOLDING}, \
LF %{MULTIPART_LF_LINE}, \
SM %{MULTIPART_SEMICOLON_MISSING}, \
IQ %{MULTIPART_INVALID_QUOTING}, \
IQ %{MULTIPART_INVALID_PART}, \
IH %{MULTIPART_INVALID_HEADER_FOLDING}, \
IH %{MULTIPART_FILE_LIMIT_EXCEEDED}'"
# Did we see anything that might be a boundary?
#
SecRule MULTIPART_UNMATCHED_BOUNDARY "!@eq 0" \
"phase:2,t:none,log,deny,status:44,msg:'Multipart parser detected a possible unmatched boundary.'"
# PCRE Tuning
# We want to avoid a potential RegEx DoS condition
#
SecPcreMatchLimit 1000
SecPcreMatchLimitRecursion 1000
# Some internal errors will set flags in TX and we will need to look for these.
# All of these are prefixed with "MSC_". The following flags currently exist:
#
# MSC_PCRE_LIMITS_EXCEEDED: PCRE match limits were exceeded.
#
SecRule TX:/^MSC_/ "!@streq 0" \
"phase:2,t:none,deny,msg:'ModSecurity internal error flagged: %{MATCHED_VAR_NAME}'"
# -- Response body handling --------------------------------------------------
# Allow ModSecurity to access response bodies.
# You should have this directive enabled in order to identify errors
# and data leakage issues.
#
# Do keep in mind that enabling this directive does increases both
# memory consumption and response latency.
#
SecResponseBodyAccess On
# Which response MIME types do you want to inspect? You should adjust the
# configuration below to catch documents but avoid static files
# (e.g., images and archives).
#
SecResponseBodyMimeType text/plain text/html text/xml
# Buffer response bodies of up to 512 KB in length.
SecResponseBodyLimit 524288
# What happens when we encounter a response body larger than the configured
# limit? By default, we process what we have and let the rest through.
# That's somewhat less secure, but does not break any legitimate pages.
#
SecResponseBodyLimitAction ProcessPartial
# -- Filesystem configuration ------------------------------------------------
# The location where ModSecurity stores temporary files (for example, when
# it needs to handle a file upload that is larger than the configured limit).
#
# This default setting is chosen due to all systems have /tmp available however,
# this is less than ideal. It is recommended that you specify a location that's private.
#
SecTmpDir /tmp/
# The location where ModSecurity will keep its persistent data. This default setting
# is chosen due to all systems have /tmp available however, it
# too should be updated to a place that other users can't access.
#
SecDataDir /tmp/
# -- File uploads handling configuration -------------------------------------
# The location where ModSecurity stores intercepted uploaded files. This
# location must be private to ModSecurity. You don't want other users on
# the server to access the files, do you?
#
#SecUploadDir /opt/modsecurity/var/upload/
# By default, only keep the files that were determined to be unusual
# in some way (by an external inspection script). For this to work you
# will also need at least one file inspection rule.
#
#SecUploadKeepFiles RelevantOnly
# Uploaded files are by default created with permissions that do not allow
# any other user to access them. You may need to relax that if you want to
# interface ModSecurity to an external program (e.g., an anti-virus).
#
#SecUploadFileMode 0600
# -- Debug log configuration -------------------------------------------------
# The default debug log configuration is to duplicate the error, warning
# and notice messages from the error log.
#
#SecDebugLog /opt/modsecurity/var/log/debug.log
#SecDebugLogLevel 3
# -- Audit log configuration -------------------------------------------------
# Log the transactions that are marked by a rule, as well as those that
# trigger a server error (determined by a 5xx or 4xx, excluding 404,
# level response status codes).
#
# To log, use RelevantOnly
SecAuditEngine RelevantOnly
SecAuditLogRelevantStatus "^(?:5|4(?!04))"
# Log everything we know about a transaction.
SecAuditLogParts ABIJDEFHZ
# Use a single file for logging. This is much easier to look at, but
# assumes that you will use the audit log only ocassionally.
#
SecAuditLogType Serial
SecAuditLog /var/log/apache2/modsec_audit.log
# Specify the path for concurrent audit logging.
#SecAuditLogStorageDir /opt/modsecurity/var/audit/
# -- Miscellaneous -----------------------------------------------------------
# Use the most commonly used application/x-www-form-urlencoded parameter
# separator. There's probably only one application somewhere that uses
# something else so don't expect to change this value.
#
SecArgumentSeparator &
# Settle on version 0 (zero) cookies, as that is what most applications
# use. Using an incorrect cookie version may open your installation to
# evasion attacks (against the rules that examine named cookies).
#
SecCookieFormat 0
与我提交有效载荷中包含 AES_ENCRYPT 的帖子的测试相关的示例规则来自/etc/modsecurity/whmcs_rules.conf：
SecRule REQUEST_URI|ARGS|REQUEST_BODY "aes_encrypt" "id:00101,phase:4,t:urlDecodeUni,t:htmlEntityDecode,t:replaceComments,t:compressWhiteSpace,t:lowercase,log,deny,msg:'WHMCS'"
SecRule REQUEST_URI|ARGS|REQUEST_BODY "aes_encrypt" "id:00102,phase:4,t:urlDecodeUni,t:htmlEntityDecode,t:hexDecode,t:replaceComments,t:compressWhiteSpace,t:lowercase,log,deny,msg:'WHMCS'"
/var/log/modsec_audit.log（摘录）
--bc497c3a-A--
[30/Oct/2013:12:33:19 +0000] UnD8jtXm0XMAABtcO10AAABA <client> 65312 <server> 443
--bc497c3a-B--
**logged, but trimmed for privacy**
--bc497c3a-C--
**logged, but trimmed for privacy**
--bc497c3a-F--
HTTP/1.1 403 Forbidden
X-Powered-By: PHP/5.3.3-7+squeeze17, PHP/5.3.3-7+squeeze17
Expires: Thu, 19 Nov 1981 08:52:00 GMT
Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Pragma: no-cache
Vary: Accept-Encoding
Content-Encoding: gzip
Keep-Alive: timeout=15, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
Content-Type: text/html; charset=UTF-8
--bc497c3a-E--
**response that is generated by the PHP script when the POST is submitted**
--bc497c3a-H--
Message: Access denied with code 403 (phase 4). Pattern match "aes_encrypt" at ARGS:firstname. [file "/etc/modsecurity/whmcs_rules.conf"] [line "41"] [id "00101"] [msg "WHMCS"]
Action: Intercepted (phase 4)
Stopwatch: 1383136398855159 530401 (- - -)
Stopwatch2: 1383136398855159 530401; combined=1155, p1=16, p2=14, p3=3, p4=1115, p5=6, sr=0, sw=1, l=0, gc=0
Response-Body-Transformed: Dechunked
Producer: ModSecurity for Apache/2.6.6 (http://www.modsecurity.org/).
Server: Apache/2.2.16 (Debian) mod_ssl/2.2.16 OpenSSL/0.9.8o
--bc497c3a-Z--
答案1
/etc/modsecurity/whmcs_rules.conf
显示为阶段：4，这是 reponse_body 位，你可能想要阶段：1（或者可能是 2），即 request_headers（和 request_body）这样 modsecurity 将更早触发
答案2
啊，ModSecurity。这是我要说的最多的了！除了问，SecRuleInheritance除了 之外，您是否在其他地方激活了该选项SecRuleEngine？
SecRuleInheritance On
SecRuleEngine On
那又怎么样SecFilterScanPOST？
SecFilterScanPOST On
另外，您使用的是哪种服务器设置？此 ModSecurity 实例是否在仅有一个主机的 Apache 设置上运行，还是您已将其设置为NameVirtualHost？
根据我几年前遇到的问题，您是否有mod_unique_id安装并激活？有些设置尽管允许安装 ModSecurity，却没有它；如果没有它，它虽然看似激活，但却无法工作。
ModSecurity 自己的网站上也有一些基本的示例解决 POST 设置。