Class: Arachni::Checks::XssEvent

Inherits:
Arachni::Check::Base show all
Defined in:
components/checks/active/xss_event.rb

Overview

It injects a string and checks if it appears inside an event attribute of any HTML tag.

Defined Under Namespace

Classes: SAX

Constant Summary collapse

ATTRIBUTES =
[
    'onload',
    'onunload',
    'onblur',
    'onchange',
    'onfocus',
    'onreset',
    'onselect',
    'onsubmit',
    'onabort',
    'onkeydown',
    'onkeypress',
    'onkeyup',
    'onclick',
    'ondblclick',
    'onmousedown',
    'onmousemove',
    'onmouseout',
    'onmouseover',
    'onmouseup',

    # Not an event attribute so it gets special treatment by being checked
    # for a "script:" prefix.
    'src'
]

Constants included from Arachni::Check::Auditor

Arachni::Check::Auditor::DOM_ELEMENTS_WITH_INPUTS, Arachni::Check::Auditor::ELEMENTS_WITH_INPUTS, Arachni::Check::Auditor::FILE_SIGNATURES, Arachni::Check::Auditor::FILE_SIGNATURES_PER_PLATFORM, Arachni::Check::Auditor::Format, Arachni::Check::Auditor::SOURCE_CODE_SIGNATURES_PER_PLATFORM

Constants included from Arachni

BANNER, Arachni::Cookie, Form, Header, JSON, Link, LinkTemplate, Severity, UIForm, UIInput, VERSION, WEBSITE, WIKI, XML

Instance Attribute Summary

Attributes included from Arachni::Check::Auditor

#framework, #page

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Arachni::Check::Base

#browser_cluster, #clean_up, elements, exempt_platforms, has_exempt_platforms?, has_platforms?, #initialize, platforms, #plugins, prefer, #preferred, preferred, #prepare, #session, supports_platforms?

Methods included from Arachni::Check::Auditor

#audit, #audit_differential, #audit_signature, #audit_timeout, #audited, #audited?, #buffered_audit, #each_candidate_dom_element, #each_candidate_element, has_timeout_candidates?, #http, #initialize, #log, #log_issue, #log_remote_file, #log_remote_file_if_exists, #match_and_log, #max_issues, #preferred, reset, #skip?, timeout_audit_run, #trace_taint, #with_browser, #with_browser_cluster

Methods inherited from Arachni::Component::Base

author, description, fullname, #shortname, shortname, shortname=, version

Methods included from Arachni::Component::Output

#depersonalize_output, #depersonalize_output?, #intercept_print_message

Methods included from UI::Output

#caller_location, #debug?, #debug_level, #debug_level_1?, #debug_level_2?, #debug_level_3?, #debug_level_4?, #debug_off, #debug_on, #disable_only_positives, #error_buffer, #error_log_fd, #error_logfile, #has_error_log?, #included, #log_error, #mute, #muted?, #only_positives, #only_positives?, #print_bad, #print_debug, #print_debug_backtrace, #print_debug_exception, #print_debug_level_1, #print_debug_level_2, #print_debug_level_3, #print_debug_level_4, #print_error, #print_error_backtrace, #print_exception, #print_info, #print_line, #print_ok, #print_status, #print_verbose, #reroute_to_file, #reroute_to_file?, reset_output_options, #set_error_logfile, #unmute, #verbose?, #verbose_off, #verbose_on

Methods included from Arachni::Component::Utilities

#read_file

Methods included from Utilities

#available_port, available_port_mutex, #bytes_to_kilobytes, #bytes_to_megabytes, #caller_name, #caller_path, #cookie_decode, #cookie_encode, #cookies_from_file, #cookies_from_parser, #cookies_from_response, #exception_jail, #exclude_path?, #follow_protocol?, #form_decode, #form_encode, #forms_from_parser, #forms_from_response, #full_and_absolute_url?, #generate_token, #get_path, #hms_to_seconds, #html_decode, #html_encode, #include_path?, #links_from_parser, #links_from_response, #normalize_url, #page_from_response, #page_from_url, #parse_set_cookie, #path_in_domain?, #path_too_deep?, #port_available?, #rand_port, #random_seed, #redundant_path?, #regexp_array_match, #remove_constants, #request_parse_body, #seconds_to_hms, #skip_page?, #skip_path?, #skip_resource?, #skip_response?, #to_absolute, #uri_decode, #uri_encode, #uri_parse, #uri_parse_query, #uri_parser, #uri_rewrite

Methods included from Arachni

URI, collect_young_objects, #get_long_win32_filename, jruby?, null_device, profile?, windows?

Constructor Details

This class inherits a constructor from Arachni::Check::Base

Class Method Details

.attribute_nameObject


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# File 'components/checks/active/xss_event.rb', line 76

def self.attribute_name
    'arachni_xss_in_element_event'
end

.infoObject


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# File 'components/checks/active/xss_event.rb', line 124

def self.info
    {
        name:        'XSS in HTML element event attribute',
        description: %q{Cross-Site Scripting in event tag of HTML element.},
        elements:    [Element::Form, Element::Link, Element::Cookie, Element::Header],
        author:      'Tasos "Zapotek" Laskos <[email protected]> ',
        version:     '0.1.9',

        issue:       {
            name:            %q{Cross-Site Scripting (XSS) in event tag of HTML element},
            description:     %q{
Client-side scripts are used extensively by modern web applications.
They perform from simple functions (such as the formatting of text) up to full
manipulation of client-side data and Operating System interaction.

Cross Site Scripting (XSS) allows clients to inject scripts into a request and
have the server return the script to the client in the response. This occurs
because the application is taking untrusted data (in this example, from the client)
and reusing it without performing any validation or sanitisation.

If the injected script is returned immediately this is known as reflected XSS.
If the injected script is stored by the server and returned to any client visiting
the affected page, then this is known as persistent XSS (also stored XSS).

Arachni has discovered that it is possible to insert script content directly into
an HTML event attribute. For example `<div onmouseover="x=INJECTION_HERE"</div>`,
where `INJECTION_HERE` represents the location where the Arachni payload was detected.
},
            references:  {
                'Secunia' => 'http://secunia.com/advisories/9716/',
                'WASC'    => 'http://projects.webappsec.org/w/page/13246920/Cross%20Site%20Scripting',
                'OWASP'   => 'https://www.owasp.org/index.php/XSS_%28Cross_Site_Scripting%29_Prevention_Cheat_Sheet'
            },
            tags:            %w(xss event injection dom attribute),
            cwe:             79,
            severity:        Severity::HIGH,
            remedy_guidance: %q{
To remedy XSS vulnerabilities, it is important to never use untrusted or unfiltered
data within the code of a HTML page.

Untrusted data can originate not only form the client but potentially a third
party or previously uploaded file etc.

Filtering of untrusted data typically involves converting special characters to
their HTML entity encoded counterparts (however, other methods do exist, see references).
These special characters include:

* `&`
* `<`
* `>`
* `"`
* `'`
* `/`

An example of HTML entity encoding is converting `<` to `&lt;`.

Although it is possible to filter untrusted input, there are five locations
within an HTML page where untrusted input (even if it has been filtered) should
never be placed:

1. Directly in a script.
2. Inside an HTML comment.
3. In an attribute name.
4. In a tag name.
5. Directly in CSS.

Each of these locations have their own form of escaping and filtering.

_Because many browsers attempt to implement XSS protection, any manual verification
of this finding should be conducted using multiple different browsers and browser
versions._
}
        }
    }
end

.optimization_cacheObject


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# File 'components/checks/active/xss_event.rb', line 92

def self.optimization_cache
    @optimization_cache ||= {}
end

.optionsObject


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# File 'components/checks/active/xss_event.rb', line 88

def self.options
    @options ||= { format: [ Format::APPEND ] }
end

.stringsObject


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# File 'components/checks/active/xss_event.rb', line 80

def self.strings
    @strings ||= [
        ";#{attribute_name}=#{random_seed}//",
        "\";#{attribute_name}=#{random_seed}//",
        "';#{attribute_name}=#{random_seed}//"
    ].map { |s| [ " script:#{s}", " #{s}" ] }.flatten
end

Instance Method Details

#check_and_log(response, element) ⇒ Object


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# File 'components/checks/active/xss_event.rb', line 110

def check_and_log( response, element )
    body = response.body

    return :checked if !(body =~ /#{self.class.attribute_name}/i)
    return if element.seed.to_s.empty? || !(body =~ /#{element.seed}/i)

    handler = SAX.new( element.seed.split( ':', 2 ).last )
    Arachni::Parser.parse( body, handler: handler )

    return :checked if !handler.proof

    log vector: element, response: response, proof: handler.proof
end

#optimization_cacheObject


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# File 'components/checks/active/xss_event.rb', line 95

def optimization_cache
    self.class.optimization_cache
end

#runObject


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# File 'components/checks/active/xss_event.rb', line 99

def run
    audit self.class.strings, self.class.options do |response, element|
        next if !response.html?

        k = "#{response.url.hash}-#{response.body.hash}".hash
        next if optimization_cache[k] == :checked

        optimization_cache[k] = check_and_log( response, element )
    end
end