Ken Johnson
159 lines
8.1 KiB
Plaintext
Executable File
159 lines
8.1 KiB
Plaintext
Executable File
<div class="widget">
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<div class="widget-header">
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<div class="title">
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<span class="fs1" aria-hidden="true" data-icon=""></span> A1 - SQL Injection
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<div class="widget-body">
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<div id="accordion1" class="accordion no-margin">
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<div class="accordion-group">
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<div class="accordion-heading">
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<a href="#collapseOne" data-parent="#accordion1" data-toggle="collapse" class="accordion-toggle">
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<i class="icon-info icon-white">
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</i>
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Description
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</a>
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</div>
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<div class="accordion-body in collapse" id="collapseOne" style="height: auto;">
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<div class="accordion-inner">
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<p>
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Injection flaws, such as SQL, OS, and LDAP injection, occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing unauthorized data.
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</p>
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</div>
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</div>
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</div>
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<div class="accordion-group">
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<div class="accordion-heading">
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<a href="#collapseTwo" data-parent="#accordion1" data-toggle="collapse" class="accordion-toggle">
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<i class="icon-bug icon-white">
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</i>
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Bug
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</a>
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</div>
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<div class="accordion-body collapse" id="collapseTwo" style="height: 0px;">
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<div class="accordion-inner">
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<p class="desc">
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This example of SQL Injection also happens to be a form of <%= link_to "Insecure Direct Object Reference", insecure_dor_tutorials_path, {:target => "_blank", :style => "color: rgb(181, 121, 158)"} %> since it uses user-supplied input to determine the user's profile to update. However, we will discuss the SQL query being used and why it is vulnerable.
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</p>
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<p>
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Within app/controllers/users_controller.rb
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</p>
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<pre class="ruby">
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def update
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message = false
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<span style="background-color:yellow"> user = User.find(:first, :conditions => "user_id = '#{params[:user][:user_id]}'")</span>
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user.skip_user_id_assign = true
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user.update_attributes(params[:user].reject { |k| k == ("password" || "password_confirmation") || "user_id" })
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pass = params[:user][:password]
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user.password = pass if !(pass.blank?)
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message = true if user.save!
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respond_to do |format|
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format.html { redirect_to user_account_settings_path(:user_id => current_user.user_id) }
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format.json { render :json => {:msg => message ? "success" : "false "} }
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end
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end
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</pre>
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<p class="desc">
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The injection vulnerability is introduced when user-supplied input is placed within the SQL string that will be executed as a query. The application will not be able to determine which portion of this query is data and which portion is a query as the user input is interpolated or co-mingled with the query string.
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</p>
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</div>
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</div>
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</div>
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<div class="accordion-group">
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<div class="accordion-heading">
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<a href="#collapseThree" data-parent="#accordion1" data-toggle="collapse" class="accordion-toggle">
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<i class="icon-lightning icon-white">
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</i>
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Solution
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</a>
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</div>
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<div class="accordion-body collapse" id="collapseThree" style="height: 0px;">
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<div class="accordion-inner">
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<p><b>SQL Injection - ATTACK</b></p>
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<p class="desc">
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You will need to use an intercepting proxy or otherwise modify the request prior to it being received by the application. Browse to account_settings (top right, drop-down). Once at the account settings page, type in passwords, and click submit. Now modify the request from:
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<p>
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<pre class="ruby">
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POST /users/5.json HTTP/1.1
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Host: railsgoat.dev
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User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:19.0) Gecko/20100101 Firefox/19.0
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Accept: */*
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Accept-Language: en-US,en;q=0.5
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Accept-Encoding: gzip, deflate
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Content-Type: application/x-www-form-urlencoded; charset=UTF-8
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X-Requested-With: XMLHttpRequest
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Referer: http://railsgoat.dev/users/5/account_settings
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Content-Length: 294
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Cookie: _railsgoat_session=[redacted]
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Connection: keep-alive
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Pragma: no-cache
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Cache-Control: no-cache
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utf8=â&_method=put&authenticity_token=GXhLKKhfBXdFx5i6iqHEd5E32Kebn1+G35eA87RW1tU=&<span style="background-color: yellow"> user[user_id]=5</span>&user[email]=ken@metacorp.com&user[first_name]=Ken&user[last_name]=Johnson&user[password]=testtest&user[password_confirmation]=testtest
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</pre>
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<p class="desc">
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Now we will inject some SQL Query syntax that will return the first result of a query that looks for users that have an admin attribute that is true. So essentially, instead of looking up the user whose data we will change by our user ID, we tell the database to return the first admin and update their data. In this instance, we are changing admin@metacorp.com's password to testtest. We can later login as that user. Granted, we could just change the user_id to 1 and do the same thing, and there are other ways to exploit this weakness but this is a clear-cut example of SQL Injection.
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</p>
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<pre class="ruby">
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POST /users/5.json HTTP/1.1
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Host: railsgoat.dev
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User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.8; rv:19.0) Gecko/20100101 Firefox/19.0
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Accept: */*
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Accept-Language: en-US,en;q=0.5
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Accept-Encoding: gzip, deflate
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Content-Type: application/x-www-form-urlencoded; charset=UTF-8
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X-Requested-With: XMLHttpRequest
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Referer: http://railsgoat.dev/users/5/account_settings
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Content-Length: 208
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Cookie: _railsgoat_session=[redacted]
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Connection: keep-alive
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Pragma: no-cache
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Cache-Control: no-cache
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utf8=â&_method=put&authenticity_token=GXhLKKhfBXdFx5i6iqHEd5E32Kebn1+G35eA87RW1tU=&<span style="background:yellow">user[user_id]=5') OR admin = 't' --'")</span>&user[password]=testtest1&user[password_confirmation]=testtest1
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</pre>
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<p><b>SQL Injection - SOLUTION</b></p>
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<p class="desc">
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In this instance, the more secure route would be to reference the current_user object versus pulling from the database manually, using POST parameters provided by the user.<br/><br/>
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</p>
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<pre class="ruby">
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def update
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message = false
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<span style="background-color:yellow">user = current_user</span>
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user.skip_user_id_assign = true
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user.update_attributes(params[:user].reject { |k| k == ("password" || "password_confirmation") || "user_id" })
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pass = params[:user][:password]
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user.password = pass if !(pass.blank?)
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message = true if user.save!
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respond_to do |format|
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format.html { redirect_to user_account_settings_path(:user_id => current_user.user_id) }
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format.json { render :json => {:msg => message ? "success" : "false "} }
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end
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end
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</pre>
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<p class="desc">
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...However, since we are discussing fixing vulnerable SQL queries, let's discuss parameterized queries. Parameterized queries separate the SQL Query from the dynamic and often untrusted data. You could replace the string interpolated value with the following query and effectively separate the query from untrusted data:
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</p>
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<pre class="ruby">
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user = User.find(:first, :conditions => ["user_id = ?", "#{params[:user][:user_id]}"])
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</pre>
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</div>
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</div>
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</div>
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<div class="accordion-group">
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<div class="accordion-heading">
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<a style="background-color: rgb(181, 121, 158)" href="#collapseFour" data-parent="#accordion1" data-toggle="collapse" class="accordion-toggle">
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<i class="icon-aid icon-white">
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</i>
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Hint
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</a>
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</div>
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<div class="accordion-body collapse" id="collapseFour" style="height: 0px;">
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<div class="accordion-inner">
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I wonder who else's account needs updating?
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</div>
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</div>
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</div>
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</div>
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</div>
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