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Secure Visitor Posting for WordPress

Normally, when visitors post a comment to your site, specific types of client data are associated with the request. Commonly, a client will provide a user agent, a referrer, and a host header. When any of these variables is absent, there is good reason to suspect foul play. For example, virtually all browsers provide some sort of user-agent name to identify themselves. Conversely, malicious scripts directly posting spam and other payloads to your site frequently operate without specifying a user agent. In the Ultimate User-Agent Blacklist, we account for the “no-user-agent” case in the very first directive, preventing a host […] Read more »

Important Security Fix for WordPress

The other day, my server crashed and Perishable Press was unable to connect to the MySQL database. Normally, when WordPress encounters a database error, it delivers a specific error message similar to the following: Read more »

Best Practices for Error Monitoring

Given my propensity to discuss matters involving error log data (e.g., monitoring malicious behavior, setting up error logs, and creating extensive blacklists), I am often asked about the best way to go about monitoring 404 and other types of server errors. While I consider myself to be a novice in this arena (there are far brighter people with much greater experience), I do spend a lot of time digging through log entries and analyzing data. So, when asked recently about my error monitoring practices, I decided to share my response here at Perishable Press, and hopefully get some good feedback […] Read more »

4G Series: The Ultimate Referrer Blacklist, Featuring Over 8000 Banned Referrers

You have seen user-agent blacklists, IP blacklists, 4G Blacklists, and everything in between. Now, in this article, for your sheer and utter amusement, I present a collection of over 8000 blacklisted referrers. For the uninitiated, in teh language of teh Web, a referrer is the online resource from whence a visitor happened to arrive at your site. For example, if Johnny the Wonder Parrot was visiting the Mainstream Media website and happened to follow a link to your site (of all places), you would look at your access logs, notice Johnny’s visit, and speak out loud (slowly): “hmmm.. it looks […] Read more »

4G Series: The Ultimate User-Agent Blacklist, Featuring Over 1200 Bad Bots

As discussed in my recent article, Eight Ways to Blacklist with Apache’s mod_rewrite, one method of stopping spammers, scrapers, email harvesters, and malicious bots is to blacklist their associated user agents. Apache enables us to target bad user agents by testing the user-agent string against a predefined blacklist of unwanted visitors. Any bot identifying itself as one of the blacklisted agents is immediately and quietly denied access. While this certainly isn’t the most effective method of securing your site against malicious behavior, it may certainly provide another layer of protection. Even so, there are several things to consider before choosing […] Read more »

The Perishable Press 4G Blacklist

Update: Check out the new and improved 6G Firewall 2016! At last! After many months of collecting data, crafting directives, and testing results, I am thrilled to announce the release of the 4G Blacklist! The 4G Blacklist is a next-generation protective firewall that secures your website against a wide range of malicious activity. Like its 3G predecessor, the 4G Blacklist is designed for use on Apache servers and is easily implemented via HTAccess or the httpd.conf configuration file. In order to function properly, the 4G Blacklist requires two specific Apache modules, mod_rewrite and mod_alias. As with the third generation of […] Read more »

Yahoo! Slurp too Stupid to be a Robot

I really hate bad robots. When a web crawler, spider, bot — or whatever you want to call it — behaves in a way that is contrary to expected and/or accepted protocols, we say that the bot is acting suspiciously, behaving badly, or just acting stupid in general. Unfortunately, there are thousands — if not hundreds of thousands — of nefarious bots violating our websites every minute of the day. For the most part, there are effective methods available enabling us to protect our sites against the endless hordes of irrelevant and mischievous bots. Such evil is easily blocked with […] Read more »

Building the Perishable Press 4G Blacklist

Last year, after much research and discussion, I built a concise, lightweight security strategy for Apache-powered websites. Prior to the development of this strategy, I relied on several extensive blacklists to protect my sites against malicious user agents and IP addresses. Unfortunately, these mega-lists eventually became unmanageable and ineffective. As increasing numbers of attacks hit my server, I began developing new techniques for defending against external threats. This work soon culminated in the release of a “next-generation” blacklist that works by targeting common elements of decentralized server attacks. Consisting of a mere 37 lines, this “2G” Blacklist provided enough protection […] Read more »

Controlling Proxy Access with HTAccess

In my recent article on blocking proxy servers, I explain how to use HTAccess to deny site access to a wide range of proxy servers. The method works great, but some readers want to know how to allow access for specific proxy servers while denying access to as many other proxies as possible. Fortunately, the solution is as simple as adding a few lines to my original proxy-blocking method. Specifically, we may allow any requests coming from our whitelist of proxy servers by testing Apache’s HTTP_REFERER variable, like so: RewriteCond %{HTTP_REFERER} !(.*)allowed-proxy-01.domain.tld(.*) RewriteCond %{HTTP_REFERER} !(.*)allowed-proxy-02.domain.tld(.*) RewriteCond %{HTTP_REFERER} !(.*)allowed-proxy-03.domain.tld(.*) Read more »

Eight Ways to Redirect with Apache’s mod_rewrite

With the imminent release of the next series of (4G) blacklist articles here at Perishable Press, now is the perfect time to examine eight of the most commonly employed blacklisting methods achieved with Apache’s incredible rewrite module, mod_rewrite. In addition to facilitating site security, the techniques presented in this article will improve your understanding of the different rewrite methods available with mod_rewrite. Note: I updated the title of this article from “Eight Ways to Blacklist..” to “Eight Ways to Redirect..”. This article uses the art of blacklisting to demonstrate how to redirect with Apache’s mod_rewrite. The examples may be modified […] Read more »

PHP Short Open Tag: Convenient Shortcut or Short Changing Security?

Most of us learned how to use “echo()” in one of our very first PHP tutorials. That was certainly the case for me. As a consequence, I never really had a need to visit PHP’s documentation page for echo(). On a recent visit to Perishable Press, I saw a Tumblr post from Jeff about the use of PHP’s shortcut syntax for echo() but somewhere deep in my memory, there lurked a warning about its use. I decided to investigate. Read more »

Yahoo! Lies about Obeying Robots.txt Directives

There are two possibilities here: Yahoo!’s Slurp crawler is broken or Yahoo! lies about obeying Robots directives. Either case isn’t good. Slurp just can’t seem to keep its nose out of my private business. And, as I’ve discussed before, this happens all the time. Here are the two most recent offenses, as recorded in the log file for my blackhole spider trap: Read more »

Blacklist Candidate 2008-10-19

Welcome to the Perishable Press “Blacklist Candidate” series. In this post, we continue our new tradition of exposing, humiliating and banishing spammers, crackers and other worthless scumbags.. From time to time on the show, a contestant places a bid that is so absurd and so asinine that you literally laugh out loud, point at the monitor, and openly ridicule the pathetic loser. On such occasions, even the host of the show will laugh and mock the idiocy. Of course, this same situation happens frequently here at Perishable Press, where the scumbags that manage to escape the 3G Blacklist are proving […] Read more »

Blacklist Candidate Series Summary

An ongoing series of articles on the fine art of malicious exploit detection and prevention. Learn about preventing the sneaky mischievous and deceptive practices of some of the worst spammers, scrapers, crackers, and other scumbags on the Internet. Read more »

Evil Incarnate, but Easily Blocked

As my readers know, I spend a lot of time digging through error logs, preventing attacks, and reporting results. Occasionally, some moron will pull a stunt that deserves exposure, public humiliation, and banishment. There is certainly no lack of this type of nonsense, as many of you are well-aware. 3G Blacklist Even so, I have to admit that I am very happy with my latest strategy against crackers, spammers, and other scumbags, namely, the 3G Blacklist. Since implementing this effective HTAccess security method, I have seen a dramatic decrease in the overall volume of malicious activity recorded in my Apache, […] Read more »

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