T1486Detection written

Data Encrypted for Impact

ImpactESXi, IaaS, Linux, macOS, Windows

Where this stands

One published detection covers this technique. Every one is unverified — no rule on Siemphony has been executed against real telemetry.

Shadow copy or backup catalog deletion from the command lineby Siemphony

What the technique is

Adversaries may encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources. They can attempt to render stored data inaccessible by encrypting files or data on local and remote drives and withholding access to a decryption key. This may be done in order to extract monetary compensation from a victim in exchange for decryption or a decryption key (ransomware) or to render data permanently inaccessible in cases where the key is not saved or transmitted. In the case of ransomware, it is typical that common user files like Office documents, PDFs, images, videos, audio, text, and source code files will be encrypted (and often renamed and/or tagged with specific file markers). Adversaries may need to first employ other behaviors, such as File and Directory Permissions Modification or System Shutdown/Reboot, in order to unlock and/or gain access to manipulate these files. In some cases, adversaries may encrypt critical system files, disk partitions, and the MBR. Adversaries may also encrypt virtual machines hosted on ESXi or other hypervisors. To maximize impact on the target organization, malware designed for encrypting data may have worm-like features to propagate across a network by leveraging other attack techniques like Valid Accounts, OS Credential Dumping, and SMB/Windows Admin Shares. […]

Read it on attack.mitre.org

What MITRE says you would watch

AN0602
High-frequency file write operations using uncommon extensions, followed by ransom note creation, registry tampering, or shadow copy deletion. Often uses CLI tools like vssadmin, wbadmin, cipher, or PowerShell.
AN0603
Encryption via custom or open-source tools (e.g., openssl, gpg, aescrypt) recursively targeting user or system directories. Also includes overwrite of existing data and ransom note drops.
AN0604
Userland or kernel-level ransomware encrypting user files (Documents, Desktop) using srm, gpg, or compiled payloads. Often correlated with ransom note creation in multiple directories.