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.^{[1],[2],[3],[4]}

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.^[5] In some cases, adversaries may encrypt critical system files, disk partitions, and the MBR.^[3] Adversaries may also encrypt virtual machines hosted on ESXi or other hypervisors.^[6]

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.^[2],[3] Encryption malware may also leverage Internal Defacement, such as changing victim wallpapers or ESXi server login messages, or otherwise intimidate victims by sending ransom notes or other messages to connected printers (known as "print bombing").^[7],[8]

In cloud environments, storage objects within compromised accounts may also be encrypted.^[9] For example, in AWS environments, adversaries may leverage services such as AWS’s Server-Side Encryption with Customer Provided Keys (SSE-C) to encrypt data.^[10]

References

1. US-CERT. (2016, March 31). Alert (TA16-091A): Ransomware and Recent Variants. Retrieved March 15, 2019.
2. Berry, A., Homan, J., and Eitzman, R. (2017, May 23). WannaCry Malware Profile. Retrieved March 15, 2019.
3. US-CERT. (2017, July 1). Alert (TA17-181A): Petya Ransomware. Retrieved March 15, 2019.
4. US-CERT. (2018, December 3). Alert (AA18-337A): SamSam Ransomware. Retrieved March 15, 2019.
5. Baskin, B. (2020, July 8). TAU Threat Discovery: Conti Ransomware. Retrieved February 17, 2021.
6. Michael Dawson. (2021, August 30). Hypervisor Jackpotting, Part 2: eCrime Actors Increase Targeting of ESXi Servers with Ransomware. Retrieved March 26, 2025.
7. NHS Digital. (2020, November 26). Egregor Ransomware The RaaS successor to Maze. Retrieved December 29, 2020.
8. Jason Hill. (2023, February 8). VMware ESXi in the Line of Ransomware Fire. Retrieved March 26, 2025.
9. Gietzen, S. (n.d.). S3 Ransomware Part 1: Attack Vector. Retrieved April 14, 2021.
10. Halcyon RISE Team. (2025, January 13). Abusing AWS Native Services: Ransomware Encrypting S3 Buckets with SSE-C. Retrieved March 18, 2025.

Propojené úkoly

• MITREATTACK -

  © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. https://attack.mitre.org/

  Terms of Use

  LICENSE

  The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use ATT&CK^® for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy.

  "© 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation."

  DISCLAIMERS

  MITRE does not claim ATT&CK enumerates all possibilities for the types of actions and behaviors documented as part of its adversary model and framework of techniques. Using the information contained within ATT&CK to address or cover full categories of techniques will not guarantee full defensive coverage as there may be undisclosed techniques or variations on existing techniques not documented by ATT&CK.

  ALL DOCUMENTS AND THE INFORMATION CONTAINED THEREIN ARE PROVIDED ON AN "AS IS" BASIS AND THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE MITRE CORPORATION, ITS BOARD OF TRUSTEES, OFFICERS, AGENTS, AND EMPLOYEES, DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

  See our FAQ for more information on how to use and represent the ATT&CK name.