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.(Citation: US-CERT Ransomware 2016)(Citation: FireEye WannaCry 2017)(Citation: US-CERT NotPetya 2017)(Citation: US-CERT SamSam 2018)

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](https://attack.mitre.org/techniques/T1222) or [System Shutdown/Reboot](https://attack.mitre.org/techniques/T1529), in order to unlock and/or gain access to manipulate these files.(Citation: CarbonBlack Conti July 2020) In some cases, adversaries may encrypt critical system files, disk partitions, and the MBR.(Citation: US-CERT NotPetya 2017) 

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](https://attack.mitre.org/techniques/T1078), [OS Credential Dumping](https://attack.mitre.org/techniques/T1003), and [SMB/Windows Admin Shares](https://attack.mitre.org/techniques/T1021/002).(Citation: FireEye WannaCry 2017)(Citation: US-CERT NotPetya 2017) Encryption malware may also leverage [Internal Defacement](https://attack.mitre.org/techniques/T1491/001), such as changing victim wallpapers, or otherwise intimidate victims by sending ransom notes or other messages to connected printers (known as "print bombing").(Citation: NHS Digital Egregor Nov 2020)

In cloud environments, storage objects within compromised accounts may also be encrypted.(Citation: Rhino S3 Ransomware Part 1)
Data Encrypted for Impact
source_name: mitre-attack  url: https://attack.mitre.org/techniques/T1486  external_id: T1486     source_name: CarbonBlack Conti July 2020  description: Baskin, B. (2020, July 8). TAU Threat Discovery: Conti Ransomware. Retrieved February 17, 2021.  url: https://www.carbonblack.com/blog/tau-threat-discovery-conti-ransomware/     source_name: FireEye WannaCry 2017  description: Berry, A., Homan, J., and Eitzman, R. (2017, May 23). WannaCry Malware Profile. Retrieved March 15, 2019.  url: https://www.fireeye.com/blog/threat-research/2017/05/wannacry-malware-profile.html     source_name: Rhino S3 Ransomware Part 1  description: Gietzen, S. (n.d.). S3 Ransomware Part 1: Attack Vector. Retrieved April 14, 2021.  url: https://rhinosecuritylabs.com/aws/s3-ransomware-part-1-attack-vector/     source_name: NHS Digital Egregor Nov 2020  description: NHS Digital. (2020, November 26). Egregor Ransomware The RaaS successor to Maze. Retrieved December 29, 2020.  url: https://digital.nhs.uk/cyber-alerts/2020/cc-3681#summary     source_name: US-CERT Ransomware 2016  description: US-CERT. (2016, March 31). Alert (TA16-091A): Ransomware and Recent Variants. Retrieved March 15, 2019.  url: https://www.us-cert.gov/ncas/alerts/TA16-091A     source_name: US-CERT NotPetya 2017  description: US-CERT. (2017, July 1). Alert (TA17-181A): Petya Ransomware. Retrieved March 15, 2019.  url: https://www.us-cert.gov/ncas/alerts/TA17-181A     source_name: US-CERT SamSam 2018  description: US-CERT. (2018, December 3). Alert (AA18-337A): SamSam Ransomware. Retrieved March 15, 2019.  url: https://www.us-cert.gov/ncas/alerts/AA18-337A     