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POST body is not inspected by modsecurity #684

code1955 opened this Issue Mar 20, 2014 · 31 comments

4 participants



We are suffering an issue related to POST inspection.
We are running modsecurity 2.7.7 on apache 2.5.3
Backend application is running on Jetty 2.9.
The application presents a login form to the end user.
When filling in the login fields with crafted data, like sql strings, the call is accepted and sent to the backend application.
But adding sql strings in the URL blocks the call.
Backend application is at risk as modsecurity is the only security control in place.
I've been suggested to enable SecStreamInBodyInspection, but it doesn't work.
Any help is welcome.

Kind regards,

SpiderLabs member

Yes, it is enabled

SpiderLabs member

Can you share the output of your ModSecurity debug log and configurations?


Here you go.
SecStreamInBodyInspection is enabled at proxy level.
I'll share reverse proxy config too

# -- 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 DetectionOnly
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" \

# 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" \
"id:'200001', 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.
"id:'200002',phase:2,t:none,log,deny,status:44, \
msg:'Multipart request body failed strict validation: \

# Did we see anything that might be a boundary?
"id:'200003',phase:2,t:none,log,deny,msg:'Multipart parser detected a possible unmatched boundary.'"

# PCRE Tuning
# We want to avoid a potential RegEx DoS condition
SecPcreMatchLimit 150000
SecPcreMatchLimitRecursion 150000

# 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" \
        "id:'200004',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  /opt/apache/common_modsecurity/modsectmp/

# 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  /opt/apache/common_modsecurity/modsecdata/

# -- 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/apache/common_modsecurity/modsecupload/

# 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/apache/common_modsecurity/modseclogs/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).
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  /opt/apache/common_modsecurity/modseclogs/modsec_audit.log

# Specify the path for concurrent audit logging.
#SecAuditLogStorageDir  /opt/apache/common_modsecurity/modseclogs/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

# Specify your Unicode Code Point.
# This mapping is used by the t:urlDecodeUni transformation function
# to properly map encoded data to your language. Properly setting
# these directives helps to reduce false positives and negatives.
SecUnicodeMapFile unicode.mapping 20127


Sorry forthe display.
I don't how to change it.

SpiderLabs member

Can you enable the SecDebugLog and share the output ?

Currently it is:
#SecDebugLog /opt/apache/common_modsecurity/modseclogs/debug.log
#SecDebugLogLevel 3

Will be great to have an output like this:
SecDebugLog /tmp/modsec-debug.log
SecDebugLogLevel 9


# Read in the default values

Include             /opt/apache/common/conf/httpd.conf
Include                         /opt/apache/common_modsecurity/httpconf/httpd-modsecurity.conf

# Mod security config

#SecRuleEngine DetectionOnly
SecRuleEngine on

SecTmpDir                       /opt/apache/
SecDataDir                      /opt/apache/
SecUploadDir                    /opt/apache/
SecDebugLog                     /opt/apache/
SecDebugLogLevel                3
SecAuditLogType                 Serial
SecAuditLog                     /opt/apache/
SecAuditLogStorageDir           /opt/apache/
SecStreamInBodyInspection   on

# Apache settings and overrides for this service

ServerRoot                      /opt/apache/

# VirtualHost definitions

User    apache

Listen                          ApacheServices1:3903
<VirtualHost                    ApacheServices1:3903>
        RewriteLog              logs/rewrite.log
        RewriteEngine           On
        RewriteLogLevel         2
        RewriteRule             ^/server-status.*               -                                               [L]
        #DocumentRoot            /opt/apache/

    RewriteRule             ^/scan/(.*)$         $1           [NC,P]
        ProxyPassReverse        /scan/       

        RewriteRule             ^/(.*)$            [NC,P]
        ProxyPassReverse        /             

    #ProxyPreserveHost  On


I'll share debug log.
It has been set at 9 to record a connection


Too much characters. I have to split it


You can paste your data here - and then put an html link here for us to view.




No Comment about this issue?


Has this issue already seen somewhere else?
Do I make a mistake?

thank you in advance for your help

SpiderLabs member

Hi @code1955, we saw that you application is exchanging JSON contents, you probably want to test our JSON branch. It supports does support to parser the JSON content. It is available here:

@zimmerle zimmerle modified the milestone: v2.8.0 Mar 27, 2014
poona commented Mar 27, 2014


Could you please capture your traffic and paste/mail/share_privately your POST payload here? You can sanitize/redact sensitive data.

poona commented Mar 27, 2014

s/Could you please/Is it possible for you to/

poona commented Mar 27, 2014

Hi @code1955
Actually I was trying to locate the entire HTTP request payload(captured from a tcpdump packet capture or through auditlog if you have configured the SecAuditEngine to "On"), which the debug log doesn't hold, afai understand. Or were you pointing at something at some other link that I'm probably missing?

SpiderLabs member

@code1955 did you had a chance to have the json branch tested?

SpiderLabs member

Download the file from GitHub, as you are doing, and then try the following:

cd /path/to/your/modsecurity-extracted-files/
make install
make test
make test-regression

double check to see if "make install" really placed the in the correct folder.

SpiderLabs member

Hi @code1955, Did you made this tests using our release candidate version or the json branch?

ModSecurity recommended configuration file contains the example to invoke the json parser:

Do you ming to share the logs again?

SpiderLabs member

Hi @code1955,

Can you provide the full log, as you did on the comment: #684 (comment) ?

Also, we have release the version 2.8.0 which incorporates the features of the json branch, it will be good to test on 2.8.0 instead.

SpiderLabs member
zimmerle commented Jul 1, 2015

Hi @code1955, yesterday I've merge #904 into nginx_refactoring branch. It should fix this issue, please confirm that the issue is fixed.

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