Data Encrypted for Impact
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. In some cases, adversaries may encrypt critical system files, disk partitions, and the MBR.[3]
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]
Procedure Examples
| Name | Description |
|---|---|
| APT38 |
APT38 has used Hermes ransomware to encrypt files with AES256.[24] |
| APT41 |
APT41 used a ransomware called Encryptor RaaS to encrypt files on the targeted systems and provide a ransom note to the user.[26] |
| JCry |
JCry has encrypted files and demanded Bitcoin to decrypt those files. [17] |
| LockerGoga |
LockerGoga has encrypted files, including core Windows OS files, using RSA-OAEP MGF1 and then demanded Bitcoin be paid for the decryption key.[12][13][14] |
| MAZE |
MAZE has disrupted systems by encrypting files on targeted machines, claiming to decrypt files if a ransom payment is made. MAZE has used the ChaCha algorithm, based on Salsa20, and an RSA algorithm to encrypt files.[20] |
| Netwalker |
Netwalker can encrypt files on infected machines to extort victims.[21] |
| NotPetya |
NotPetya encrypts user files and disk structures like the MBR with 2048-bit RSA.[10][3] |
| Ragnar Locker |
Ragnar Locker encrypts files on the local machine and mapped drives prior to displaying a note demanding a ransom.[22][23] |
| RobbinHood |
RobbinHood will search for an RSA encryption key and then perform its encryption process on the system files.[18] |
| Ryuk |
Ryuk has used a combination of symmetric (AES) and asymmetric (RSA) encryption to encrypt files. Files have been encrypted with their own AES key and given a file extension of .RYK. Encrypted directories have had a ransom note of RyukReadMe.txt written to the directory.[19] |
| SamSam |
SamSam encrypts victim files using RSA-2048 encryption and demands a ransom be paid in Bitcoin to decrypt those files.[11] |
| Shamoon |
Shamoon has an operational mode for encrypting data instead of overwriting it.[6][7] |
| SynAck |
SynAck encrypts the victims machine followed by asking the victim to pay a ransom. [16] |
| TA505 |
TA505 has used a wide variety of ransomware, such as Locky, Jaff, Bart, Philadelphia, and GlobeImposter, to encrypt victim files and demand a ransom payment.[25] |
| WannaCry |
WannaCry encrypts user files and demands that a ransom be paid in Bitcoin to decrypt those files.[8][2][9] |
| Xbash |
Xbash has maliciously encrypted victim's database systems and demanded a cryptocurrency ransom be paid.[15] |
Mitigations
| Mitigation | Description |
|---|---|
| Data Backup |
Consider implementing IT disaster recovery plans that contain procedures for regularly taking and testing data backups that can be used to restore organizational data.[5] Ensure backups are stored off system and is protected from common methods adversaries may use to gain access and destroy the backups to prevent recovery. |
Detection
Use process monitoring to monitor the execution and command line parameters of of binaries involved in data destruction activity, such as vssadmin, wbadmin, and bcdedit. Monitor for the creation of suspicious files as well as unusual file modification activity. In particular, look for large quantities of file modifications in user directories.
In some cases, monitoring for unusual kernel driver installation activity can aid in detection.
References
- US-CERT. (2016, March 31). Alert (TA16-091A): Ransomware and Recent Variants. Retrieved March 15, 2019.
- Berry, A., Homan, J., and Eitzman, R. (2017, May 23). WannaCry Malware Profile. Retrieved March 15, 2019.
- US-CERT. (2017, July 1). Alert (TA17-181A): Petya Ransomware. Retrieved March 15, 2019.
- US-CERT. (2018, December 3). Alert (AA18-337A): SamSam Ransomware. Retrieved March 15, 2019.
- Ready.gov. (n.d.). IT Disaster Recovery Plan. Retrieved March 15, 2019.
- Falcone, R.. (2016, November 30). Shamoon 2: Return of the Disttrack Wiper. Retrieved January 11, 2017.
- Falcone, R. (2018, December 13). Shamoon 3 Targets Oil and Gas Organization. Retrieved March 14, 2019.
- Noerenberg, E., Costis, A., and Quist, N. (2017, May 16). A Technical Analysis of WannaCry Ransomware. Retrieved March 25, 2019.
- Counter Threat Unit Research Team. (2017, May 18). WCry Ransomware Analysis. Retrieved March 26, 2019.
- Chiu, A. (2016, June 27). New Ransomware Variant "Nyetya" Compromises Systems Worldwide. Retrieved March 26, 2019.
- Palotay, D. and Mackenzie, P. (2018, April). SamSam Ransomware Chooses Its Targets Carefully. Retrieved April 15, 2019.
- CarbonBlack Threat Analysis Unit. (2019, March 22). TAU Threat Intelligence Notification – LockerGoga Ransomware. Retrieved April 16, 2019.
- Harbison, M.. (2019, March 26). Born This Way? Origins of LockerGoga. Retrieved April 16, 2019.
- Greenberg, A. (2019, March 25). A Guide to LockerGoga, the Ransomware Crippling Industrial Firms. Retrieved July 17, 2019.
- Xiao, C. (2018, September 17). Xbash Combines Botnet, Ransomware, Coinmining in Worm that Targets Linux and Windows. Retrieved November 14, 2018.
- Ivanov, A. et al.. (2018, May 7). SynAck targeted ransomware uses the Doppelgänging technique. Retrieved May 22, 2018.
- Lee, S.. (2019, May 14). JCry Ransomware. Retrieved June 18, 2019.
- Lee, S. (2019, May 17). CB TAU Threat Intelligence Notification: RobbinHood Ransomware Stops 181 Windows Services Before Encryption. Retrieved July 29, 2019.
- Hanel, A. (2019, January 10). Big Game Hunting with Ryuk: Another Lucrative Targeted Ransomware. Retrieved May 12, 2020.
- Kennelly, J., Goody, K., Shilko, J. (2020, May 7). Navigating the MAZE: Tactics, Techniques and Procedures Associated With MAZE Ransomware Incidents. Retrieved May 18, 2020.
- Victor, K.. (2020, May 18). Netwalker Fileless Ransomware Injected via Reflective Loading . Retrieved May 26, 2020.
- SophosLabs. (2020, May 21). Ragnar Locker ransomware deploys virtual machine to dodge security. Retrieved June 29, 2020.
- Gold, B. (2020, April 27). Cynet Detection Report: Ragnar Locker Ransomware. Retrieved June 29, 2020.
- FireEye. (2018, October 03). APT38: Un-usual Suspects. Retrieved November 6, 2018.
- Proofpoint Staff. (2017, September 27). Threat Actor Profile: TA505, From Dridex to GlobeImposter. Retrieved May 28, 2019.
- Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.