Skip to main content

A tool that generates ModSecurity exception rules by automatically analyzing ModSecurity audit logs.

Project description

ModSecurity Exception Generator is a tool that generates ModSecurity exception rules by automatically analyzing ModSecurity audit logs. This is very useful and almost essential to avoid false positives and rejecting legitimate clients.


pip install modsecurity-exception-generator


Command options


SQL URL of the data store where the ModSecurity audit log parsed data will be stored and loaded from.

Example: ‘sqlite:////tmp/modsecurity-exception-factory.db’.

-i [Optional]

Path to the ModSecurity audit log file to parse.

One can use ‘-’ as a value for this parameter to read the audit log data from standard input.

-c [Optional]

Path of the optional configuration file.

Basic examples

modsecurity-exception-generator \
    -i /path/to/modsec_audit.log \
    -d "sqlite:////tmp/service.db" \
> modsecurity_crs_15_exceptions.conf
zcat modsec_audit.log.*.gz \
| modsecurity-exception-generator \
    -i - \
    -d "sqlite:////tmp/service.db" \
> modsecurity_crs_15_exceptions.conf


The produced exceptions must be loaded BEFORE the rules they are applied to.

Removing superfluous exceptions

Generating exceptions by simply running the ‘modsecurity-exception-generator’ program, as in the basic examples, might generate some superfluous exception rules. Thus we need some advanced options to obtain smarter results. That’s where the YAML configuration file given using the ‘-c’ option comes in handy.

The YAML configuration file supports the following directives:


Indicates which logs most be ignored by the exception generator.


To ignore any log message produced by the rule with the id 981176.

   rule_id: [981176]

This can also be applied to other variables like ‘host_name(targeted host name), ‘request_filename(targeted url) or ‘payload_container(the variable that matched the rule).


Ignore exceptions that affect less than minimum_occurence_count_threshold log message occurrences.


Sometimes, exceptions rules can have conditions with too many values like the following example.

SecRule REQUEST_FILENAME "@rx ^(/foo_bar|/blabla|/test_2/|...)$" ...

This condition can be ignored by setting maximum_value_count_threshold to a value lesser than the number of values in the regular expression.

Configuration example for the Core Rule Set

    rule_id: [981174, 981176, 981203, 981200, 981201, 981202, 981203, 981204, 981205, 981220]

minimum_occurrence_count_threshold: 1000

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

modsecurity-exception-factory-0.1.4.tar.gz (19.1 kB view hashes)

Uploaded source

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Huawei Huawei PSF Sponsor Microsoft Microsoft PSF Sponsor NVIDIA NVIDIA PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page