Using Url Rewrite to Block Page Requests
The other day I was checking the traffic stats for my WordPress blog to see which of my posts were the most popular. I was a little concerned to see that wp-login.php was in the Top 5 total requests almost every month. Since I’m the only author on my blog my logins could not possibly account for the traffic hitting that page.
The only explanation could be that the additional traffic was coming from automated hacking attempts. Any server administrator concerned about security knows that “footprinting” is one of the first things a hacker will do when checking for vulnerable sites. I checked a few of my non-wordpress sites and sure enough every couple of days page requests were coming in for wp-login.php and urls for other CMS products such as Plesk’s Cpanel.
Using log parser I wanted to see how many IPs were hitting my login page during a particular month. I like to keep my complex queries in a separate query file and then output the results to a text file. In a previous post I showed how you can leverage this technique to automate log parser to run multiple queries at once. Here’s the query I used to check every log file for my site in the month of October. So this query outputs a simple text file clearly showing thousands of requests to wp-login.php from across the internet during the month of October.
logparser.exe file:wplogin.sql?destination=wpadmin.txt -o:NAT
Here is the SQL query contained in wplogin.sql. I am using a couple of advanced techniques such as searching in multiple log files and filtering the dates to get a results for one month:
SELECT c-ip, COUNT(*) AS TotalHits
FROM ./log/u_ex*.log TO %destination%
where (EXTRACT_FILENAME(cs-uri-stem) = 'wp-login.php'
and TO_STRING(To_timestamp(date, time), 'MM')='10'
GROUP BY c-ip
ORDER BY TotalHits DESC
Having always followed best practices for hosting sites I was confident that my sites were not vulnerable to these automated probes but it was still a bit irksome to know they were occurring. And there’s always the possibility of some zero-day exploit showing up so I decided the simplest thing do was to block them. IIS now has a great new module available for Dynamic IP Restrictions however that would only block the requests once a threshold was reached. I needed something more “nuclear”. I wanted a means to block everyone hitting that page except for me and the help of the IIS Url Rewrite module a simple rewrite rule was going to do the trick.
In another previous post I showed how easy it was to use Url Rewrite for SEO and security. Now you can see how to tighten security even more by aborting requests based on almost any criteria. In my particular case I wanted to abort requests to wp-login.php from any IP address except for my own IP. So the next logical question is “what’s my ip address?” There are several sites online which can offer you this information. Probably the easiest to remember is whatsmyip.org. When you visit that site, your public IP address is displayed very clearly at the top of the page. This is the IP that you want to put in the rule below. It is important to note the use of “negate=true”. This means all IPs except for the one referenced. The next logical question is what if I need to login to WordPress from more than 1 IP address such as from home and at the office? This is a simple matter of just adding an additional condition to the rule below.
<rewrite>
<rules>
<rule name="Block wp login" stopprocessing="true">
<match url="(^wp-login.php)" ignorecase="true" />
<conditions>
<add negate="true" pattern="10\.10\.10\.10" input="{REMOTE_ADDR}" />
</conditions>
<action type="AbortRequest" />
</rule>
</rules>
<rewrite>
So in summary Log Parser makes it very easy to get quick extracts of data from your web site’s logs and IIS 7’s Url Rewrite module not only offers powerful rewriting and redirecting of urls but also an easy way to tighten the security of your site. Thanks for reading.
