5G Blacklist for Microsoft IIS

By design the 5G Blacklist works on Apache servers, but thanks to Scott Stawarz, here is a version for Microsoft IIS. Disclaimer: I do not use any Microsoft server stuff, so make sure to properly test everything before running this code on a live/production site. Also, if you scroll down to the end of this article, you will find some useful bonus snippets.

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
  <system.webServer>
    <rewrite>
      <rules>
                <clear />
                <rule name="Block Bad Query String" stopProcessing="true">
                    <match url=".*" ignoreCase="false" />
                    <conditions logicalGrouping="MatchAny" trackAllCaptures="false">
                        <add input="{QUERY_STRING}" pattern="(environ|localhost|mosconfig|scanner)" />
                        <add input="{QUERY_STRING}" pattern="(menu|mod|path|tag)\=\.?/?" />
                        <add input="{QUERY_STRING}" pattern="boot\.ini" />
                        <add input="{QUERY_STRING}" pattern="echo.*kae" />
                        <add input="{QUERY_STRING}" pattern="etc/passwd" />
                        <add input="{QUERY_STRING}" pattern="\=\\%27$" />
                        <add input="{QUERY_STRING}" pattern="\=\\\'$" />
                        <add input="{QUERY_STRING}" pattern="\.\./" />
                        <add input="{QUERY_STRING}" pattern="\:" />
                        <add input="{QUERY_STRING}" pattern="\[" />
                        <add input="{QUERY_STRING}" pattern="\]" />
                    </conditions>
                    <action type="CustomResponse" statusCode="403" statusReason="Forbidden" statusDescription="Forbidden" />
                </rule>
                <rule name="Block Bad User Agents" stopProcessing="true">
                    <match url=".*" />
                    <conditions logicalGrouping="MatchAny" trackAllCaptures="false">
                        <add input="{HTTP_USER_AGENT}" pattern=" ^$" />
                        <add input="{HTTP_USER_AGENT}" pattern="(casper|cmsworldmap|diavol|dotbot)" />
                        <add input="{HTTP_USER_AGENT}" pattern="(flicky|ia_archiver|kmccrew)" />
                        <add input="{HTTP_USER_AGENT}" pattern="(libwww|planetwork|pycurl|skygrid)" />
                    </conditions>
                    <action type="CustomResponse" statusCode="403" statusReason="Forbidden: Access is denied." statusDescription="You do not have permission to view this directory or page using the credentials that you supplied." />
                </rule>
                <rule name="Block Bad Request Strings" stopProcessing="true">
                    <match url=".*" />
                    <conditions logicalGrouping="MatchAny" trackAllCaptures="false">
                        <add input="{URL}" pattern="(https?|ftp|php)\://" />
                        <add input="{URL}" pattern="/(cgi|https?|ima|ucp)/" />
                        <add input="{URL}" pattern="(\=\\\'|\=\\%27|/\\\'/?|\)\.css\()$" />
                        <add input="{URL}" pattern="(\,|//|\)\+|/\,/|\{0\}|\(/\(|\.\.\.|\+\+\+|\|)" />
                        <add input="{URL}" pattern="\.(cgi|asp|aspx|cfg|dll|exe|jsp|mdb|sql|ini|rar)$" />
                        <add input="{URL}" pattern="/(contac|fpw|install|pingserver|register)\.php" />
                        <add input="{URL}" pattern="(base64|crossdomain|localhost|wwwroot)" />
                        <add input="{URL}" pattern="\.well\-known/host\-meta" />
                        <add input="{URL}" pattern="/function\.array\-rand" />
                        <add input="{URL}" pattern="\)\;\$\(this\)\.html\(" />
                        <add input="{URL}" pattern="proc/self/environ" />
                        <add input="{URL}" pattern="/ref\.outcontrol" />
                        <add input="{URL}" pattern="indonesia\.htm" />
                        <add input="{URL}" pattern="\{\$itemURL\}" />
                        <add input="{URL}" pattern="function\(\)" />
                        <add input="{URL}" pattern="labels\.rdf" />
                    </conditions>
                    <action type="CustomResponse" statusCode="403" statusReason="Forbidden: Access is denied." statusDescription="You do not have permission to view this directory or page using the credentials that you supplied." />
                </rule>
      </rules>
    </rewrite>
  </system.webServer>
</configuration>

Just copy/paste into your web.config file and you should be good to go. I really don’t know much about IIS, but this code looks logical to me and should be entirely plug-n-play, so no editing required. If you discover bugs or have ways of improving the code, please share via comment or directly.

Tested on IIS version 7.5.

Bonus

In his IIS version of 5G, Scott included a couple of bonus rules, one for protecting against hotlinking, and another for WordPress permalinks:

                <rule name="Prevent Image HotLinking">
                    <match url=".*\.(gif|jpg|png)$" />
                    <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
                        <add input="{HTTP_REFERER}" pattern="^$" negate="true" />
                        <add input="{HTTP_REFERER}" pattern="^http(s)?://(.*\.)?your-domain-name-goes-here\.com/.*$" negate="true" />
                    </conditions>
                    <action type="Rewrite" url="/some-random-directory/some-random-file.html" />
                </rule>
                <rule name="wordpress" patternSyntax="Wildcard">
                    <match url="*" />
                    <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
                        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
                    </conditions>
                    <action type="Rewrite" url="index.php" />
                </rule>

This code is pre-indented for easy copy/paste into the 5G/IIS code.

Huge thanks to Scott for sharing his work with us!

Credit link: Screenflex Room Dividers

About the Author

Jeff Starr = Fullstack Developer. Book Author. Teacher. Human Being.