Cloud-hosted servers are at the root of yet another malware outbreak as more than 4,000 ElasticSearch servers, most hosted on AWS, have been found to be infected with two strains of malware aimed at point-of-sale (POS) terminals. The malware -- AlinaPOS and JackPOS -- has been around for at least five years but is now being widely sold on dark web malware sites.

Researchers at Kromtech discovered the malware instances during research on Elasticsearch and found that many of the servers had been infected multiple times with multiple versions of the malware. The question is, why were the Elasticsearch instances on AWS hit particularly hard?

Elasticsearch is an open-source search and analytics engine that is fully indexed so searches are very fast. It can run on very small hardware footprints and that's why so many Elasticsearch servers are hosted on AWS -- and why a particular vulnerability to this malware exists. According to the Kromtech research blog post:

Amazon Web Services provides customers with a free T2 micro (EC2 / Elastic Compute Cloud) instance with up to 10 Gb of disk space. These T2 instances are designed for operations that don't use the full CPU for general purpose workloads, such as web servers, developer environments, and small databases. The problem is that on the T2 micro, you can set only versions 1.5.2 and 2.3.2.

Amazon makes it very fast and very easy to set up one of these Elasticsearch instances. Unfortunately, the speed and ease make it very fast and easy to skip all the security settings, leaving both functionality and administration of the Elasticsearch instance open to the world. And everyone knows that there is little that a hacker loves more than an unlocked, open instance.

So what are companies to do with Elasticsearch instances that they now assume to be infected? The Kromtech Security Center has a list of suggestion in the blog post announcing the find; the points of the list boil down to tear down the instance, throw it away and start over from a known-good image.

Elastic has their own list of security suggestions which are largely things that should be done as part of all security processes for all applications and infrastructure components. To both of these sets of suggestions, Security Now has one more that seems necessary on the heels of recent vulnerabilities.

Be careful when you configure cloud-based servers. Don't click in rapid-fire fashion through security questions and setup parameters. Take the few minutes required to understand what you're setting up and why. Proper cloud setup isn't necessarily hard: It just takes thought and a little bit of patience. And it could pay off in the joy that comes through knowing that you're not a major stop on the dark web malware repository road.

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— Curtis Franklin is the editor of SecurityNow.com. Follow him on Twitter @kg4gwa.