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Virtual machines enabled a revolution in cloud computing by providing a way to deliver more scalable, cost-effective and flexible compute resources. But despite their legitimate uses, they also open the door to fraud by helping fraudsters evade detection, scale attacks or carry out other malicious activities.
To stop fraudsters from exploiting this technology, it’s crucial that businesses understand the fraudulent uses of virtual machines and the techniques for detecting them. This blog post will explain what virtual machines are, how they are used for fraud and how to identify and block their malicious usage.
A virtual machine, or VM, is a virtualized computing system that can simulate different operating systems or run multiple OSes on a single physical machine. VMs are popular among fraudsters since they spend time on the dark web downloading tools and finding ways to exploit vulnerabilities. By using a VM, they can conduct these activities while protecting their physical devices from being traced or harmed.
VMs also pose a threat to businesses, as attackers can use them for a variety of malicious activities, including:
As a result, the use of a VM can be an indicator of attempted fraud, especially when its usage is uncommon for a trusted user or accompanied by other risk signals and anomalies.
When detecting VM usage, we can split the data into two categories:
Those in the first category carry distinctive signatures of a VM vendor or VM-related GPU and CPU signatures, as you can see below.
However, VMs that disguise their usage can be tricky to spot at first glance. But if we dive a bit more deeper, we can discover some interesting properties that indicate we’re not facing an innocent machine.
To help detect these properties, our Security Research Labs studied the properties of VMs by creating various virtual machines and observing the output of our SDK. We used a cloud-based windows machine, UTM, for local virtualization on a MacBook with Apple silicon and a VirtualBox from a Windows PC.
Below, you can see an example of a UTM machine and its settings.
And here is an example of our demo site running on the Linux distribution Kali Linux, an open-source operating system that includes tools that allow users to control and monitor information about running VMs.
Using these tools, our security researchers performed tests and trials that provided leads for new detection methods of VMs, which we describe in the next section.
Since most normal user traffic does not come from VMs or spoofed devices, we have a good amount of data that helps us understand each hardware platform’s performance by performing computational and rendering tests. Using this data, we can sample each hardware platform’s performance and compare it to each new instance from the VMs we created in order to determine its standard deviation from the mean of the distribution.
All modern physical machines these days come with at least two logical cores: one physical and one thread, which is a sequence of instructions within a program that can be executed by a logical core.
Since physical machines typically have a fixed number of logical cores determined by the underlying hardware architecture, discrepancies in the number of cores expected — such as a very high even number of cores or an odd number of cores with signatures of known CPUs — could strongly indicate the use of a VM.
In modern computer hardware, there are two main architectures, RISC (reduced instruction set computer) and CISC (complex instruction set computer). RISC CPUs and platforms are primarily known as ARM CPUs, which can be found in almost all mobile devices and some desktop computers, such as Apple M1s. CISC CPUs and platforms are mainly known as x86 and come in 32 or 64-bit configuration (Intel and AMD).
From researching odd-numbered core instances, we noticed that sometimes x86 CPUs came with ARM-related graphics and vice-versa, such as AMD CPUs that came with Intel internal graphics. We can also sample all platform instances and find the most common ones for each platform in order to spot anomalies.
Device characteristics can also be used as factors to suggest the possible use of VMs. This includes:
By sampling the clean data and looking for anomalies, we can gain even more information about the specific patterns in device characteristics that can indicate VM usage, as seen in the graph below showing the distribution of screen resolution.
The new insights and detection methods of VMs and spoofed devices that we learned through our research yielded new features and segmentations of our data that can be used to optimize the detection of fraudulent VM usage. Transmit Security’s Detection and Response Services leverage the information gained from our Security Research Labs to optimize our machine-learning based risk engine to detect emerging threat patterns.
By training our machine-learning models with the data we learned from these experiments, we can not only identify hard-coded features of virtual machines, but generate more labels for our data to use in supervised machine-learning algorithms and leverage it for more advanced machine-learning techniques, such as unsupervised or semi-supervised algorithms.
To find out more, read about how Detection and Response Services use machine-learning based anomaly detection to uncover threat patterns or check out our Attack Simulator to see for yourself how VM-based attacks differ from legitimate traffic.
