Lots of PHP Web Shells Still Circulating

Many PHP-based web shells are still making the rounds, and while many of them are based on old code, mutations, customizations and updates abound. They are so common, that new variants and modified versions are often seen at the rate of about 10 a day in our TigerTrax Threat Intelligence systems and honeypots.

Variants exist for a wide variety of platforms and human languages, many with some very nasty features and even some cool ASCII art. There are many variants for attackers to choose from for just about any of the popular PHP-based content management platforms. From WordPress to Joomla and beyond to the far less common apps, there are easily used exploits and shell kits widely available.

If you run a PHP-based site or server, it’s a good idea to keep an eye on the file system changes and watch closely for new files being uploaded or added. Pay particular attention to those using the “base64_decode” function, since it is so common among these tools.

Thanks for reading, and until next time, stay safe out there! 

Scanning Targets for PHP My Admin Scans

Another quick update today. This time an updated list of the common locations where web scanning tools in the wild are checking for PHPMyAdmin. As you know, this is one of the most common attacks against PHP sites. You should check to make sure your site does not have a real file in these locations or that if it exists, it is properly secured.

The scanners are checking the following locations these days:


Quick PHP Malware vs AV Update

It’s been a while since I checked on the status of PHP malware versus anti-virus. So, here is a quick catch up post. (I’ve been talking about this for a while now. Here is an old example.)

I took a randomly selected piece of PHP malware from the HITME and checked it out this afternoon. Much to my surprise, the malware detection via AV has gotten better.

The malware I grabbed for the test turned out to be a multi-stage PHP backdoor. The scanner thought it was exploiting a vulnerable WordPress installation. 

I unpacked the malware parts into plain text and presented both the original packed version from the log and the unpacked version to VirusTotal for detection testing. As you know, in the past, detection of malware PHP was sub single digits in many cases. That, at least to some extent has changed. For those interested, here are the links to see what was tripped.

Decoded to plain text vs Encoded, as received

As you can see, decoded to plain text scored a detection of 44% (19/43), which is significantly improved from a year or so ago. Additionally, excitingly, undecoded, the attack in raw form triggered a detection rate of 30% (13/44)! The undecoded result is HUGE, given that the same test a year or so ago often yielded 0-2% detection rates. So, it’s getting better, just SLOWLY.

Sadly though, even with the improvements, we are still well below half (50%) detection rates and many of the AV solutions that fail to catch the PHP malware are big name vendors with commercial products that organizations running PHP in commercial environments would likely be depending on. Is your AV in the missing zone? If so, you might want to consider other forms of more nuanced detection

Now, obviously, organizations aren’t just depending on AV alone for detection of web malware. But, many may be. In fact, a quick search for the dropped backdoor file on Google showed 58,800 systems with the dropped page name (a semi-unique indicator of compromise). With that many targets already victim to this single variant of PHP backdoors, it might be worth checking into if you are a corporate PHP user.

Until next time, take a look around for PHP in your organization. It is a commonly missed item in the patch and update cycles. It also has a pretty wide security posture with a long list of known attack tools and common vulnerabilities in the coding patterns used by many popular products. Give any PHP servers you have a deeper inspection and consider adding more detection capability around them. As always, thanks for reading and stay safe out there! 

More Chinese Scans for Web Bugs

This morning I was checking through my usual HoneyPoint deployments and it was a normal day. As usual, the last 24 hours brought a large number of web application bug scans from hosts in China. They are the normal PHP discovery probes, some basic malware dropper probes against known web vulnerabilities and a ton of web server fingerprinting probes from various Chinese hosts.

China has now surpassed the US as the source of most global probes and attacks, a least according to Arbor. Check out the China profile here.

One of my close friends, JK, claims that there is a massive initiative underway in China to map the Internet on a global scale and to have a fairly up to date global vulnerability matrix for the world’s systems. While this could be true, and is certainly possible, with a large enough set of bot-infected hosts that dropped data back to a centralized database, it is an interesting thought.

For sure, these probes and scans exist on a global basis. Our international HoneyPoints pick up much of the same Chinese traffic as our US ones. Perhaps a quick check of some of your logs will show the same. Much discussion of pro-active blocks against Chinese address space is underway in several organizations. Perhaps this is something we should all think about?