Hide Artifacts: Run Virtual Instance
Adversaries may carry out malicious operations using a virtual instance to avoid detection. A wide variety of virtualization technologies exist that allow for the emulation of a computer or computing environment. By running malicious code inside of a virtual instance, adversaries can hide artifacts associated with their behavior from security tools that are unable to monitor activity inside the virtual instance. Additionally, depending on the virtual networking implementation (ex: bridged adapter), network traffic generated by the virtual instance can be difficult to trace back to the compromised host as the IP address and hostname might not match known values.
Adversaries may utilize native support for virtualization (ex: Hyper-V) or drop the necessary files to run a virtual instance (ex: VirtualBox binaries). After running a virtual instance, adversaries may create a shared folder between the guest and host with permissions that enable the virtual instance to interact with the host file system.
Maze operators have used VirtualBox and a Windows 7 virtual machine to run the ransomware; the virtual machine's configuration file mapped the shared network drives of the target company, presumably so Maze can encrypt files on the shared drives as well as the local machine.
Ragnar Locker has used VirtualBox and a stripped Windows XP virtual machine to run itself. The use of a shared folder specified in the configuration enables Ragnar Locker to encrypt files on the host operating system, including files on any mapped drives.
|Disable or Remove Feature or Program||
Disable Hyper-V if not necessary within a given environment.
Use application control to mitigate installation and use of unapproved virtualization software.
Consider monitoring for files and processes associated with running a virtual instance, such as binary files associated with common virtualization technologies (ex: VirtualBox, VMware, QEMU, Hyper-V). Consider monitoring for process command-line arguments that may be atypical for benign use of virtualization software. Usage of virtualization binaries or command-line arguments associated with running a headless (in the background with no UI) virtual instance may be especially suspect. Network adapter information may also be helpful in detecting the use of virtual instances.
If virtualization software is installed by the adversary, the Registry may provide detection opportunities. Consider monitoring for Windows Service, with respect to virtualization software.
Benign usage of virtualization technology is common in enterprise environments, data and events should not be viewed in isolation, but as part of a chain of behavior.
- Committee of Inquiry into the Cyber Attack on SingHealth. (2019, January 10). Public Report of the Committee of Inquiry into the Cyber Attack on Singapore Health Services Private Limited's Patient Database. Retrieved June 29, 2020.
- SophosLabs. (2020, May 21). Ragnar Locker ransomware deploys virtual machine to dodge security. Retrieved June 29, 2020.