Technique.View on attack.mitre.org
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. 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").
In cloud environments, storage objects within compromised accounts may also be encrypted. 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.
Rules on DetectionCode tagged with T1486.
| Rule | Level | Log source |
|---|---|---|
| Antivirus - Ransomware Signature | critical | NULL / antivirus |
| AWS KMS Imported Key Material Usage | high | aws / NULL |
| Load Of RstrtMgr.DLL By A Suspicious Process | high | windows / image_load |
| Renamed Gpg.EXE Execution | high | windows / process_creation |
| Suspicious Creation TXT File in User Desktop | high | windows / file_event |
| Suspicious Reg Add BitLocker | high | windows / process_creation |
| AWS EC2 Disable EBS Encryption | medium | aws / NULL |
| Microsoft 365 - Potential Ransomware Activity | medium | m365 / NULL |
| Portable Gpg.EXE Execution | medium | windows / process_creation |
| Suspicious Appended Extension | medium | windows / file_rename |
| Load Of RstrtMgr.DLL By An Uncommon Process | low | windows / image_load |
| Rule | Type | Risk | Data source |
|---|---|---|---|
| ASL AWS Detect Users creating keys with encrypt policy without MFA | TTP | NULL | ASL AWS CloudTrail |
| AWS Detect Users creating keys with encrypt policy without MFA | TTP | NULL | AWS CloudTrail CreateKey, AWS CloudTrail PutKeyPolicy |
| AWS Detect Users with KMS keys performing encryption S3 | Anomaly | NULL | AWS CloudTrail |
| High Process Termination Frequency | Anomaly | NULL | Sysmon EventID 5 |
| Ransomware Notes bulk creation | Anomaly | NULL | Sysmon EventID 11 |
| Ryuk Test Files Detected | TTP | NULL | Sysmon EventID 11 |
| Samsam Test File Write | TTP | NULL | Sysmon EventID 11 |
| Windows .Key File Creation in Root Directory | Anomaly | NULL | Sysmon EventID 11 |
| Windows BitLocker Suspicious Command Usage | TTP | NULL | Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2 |
| Windows DiskCryptor Usage | Hunting | NULL | Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2 |
| Used by | Procedure example |
|---|---|
| GroupAkira | Akira encrypts files in victim environments as part of ransomware operations. |
| GroupAPT38 | APT38 has used Hermes ransomware to encrypt files with AES256. |
| GroupAPT41 | APT41 used a ransomware called Encryptor RaaS to encrypt files on the targeted systems and provide a ransom note to the user. APT41 also used Microsoft Bitlocker to encrypt workstations and Jetico’s BestCrypt to encrypt servers. |
| GroupBlackByte | BlackByte has encrypted victim files for ransom. Early versions of BlackByte ransomware used a common key for encryption, but later versions use unique keys per victim. |
| GroupFIN7 | FIN7 has encrypted virtual disk volumes on ESXi servers using a version of Darkside ransomware. Additionally, FIN7 has deployed ransomware as the end payload during big game hunting. |
| GroupFIN8 | FIN8 has deployed ransomware such as Ragnar Locker, White Rabbit, and attempted to execute Noberus on compromised networks. |
| GroupINC Ransom | INC Ransom has used INC Ransomware to encrypt victim's data. |
| GroupIndrik Spider | Indrik Spider has encrypted domain-controlled systems using BitPaymer. Additionally, Indrik Spider used PsExec to execute a ransomware script. |
| Used by | Procedure example |
|---|---|
| MalwareAkira | Akira can encrypt victim filesystems for financial extortion purposes including through the use of the ChaCha20 and ChaCha8 stream ciphers. |
| MalwareAkira _v2 | The Akira _v2 encryptor targets the `/vmfs/volumes/` path by default and can use the rust-crypto 0.2.36 library crate for the encryption processes. |
| MalwareApostle | Apostle creates new, encrypted versions of files then deletes the originals, with the new filenames consisting of a random GUID and ".lock" for an extension. |
| MalwareAvaddon | Avaddon encrypts the victim system using a combination of AES256 and RSA encryption schemes. |
| MalwareAvosLocker | AvosLocker has encrypted files and network resources using AES-256 and added an `.avos`, `.avos2`, or `.AvosLinux` extension to filenames. |
| MalwareBabuk | Babuk can use ChaCha8 and ECDH to encrypt data. |
| MalwareBad Rabbit | Bad Rabbit has encrypted files and disks using AES-128-CBC and RSA-2048. |
| MalwareBitPaymer | BitPaymer can import a hard-coded RSA 1024-bit public key, generate a 128-bit RC4 key for each file, and encrypt the file in place, appending |
| Used by | Procedure example |
|---|---|
| CampaignC0015 | During C0015, the threat actors used Conti ransomware to encrypt a compromised network. |
| CampaignC0018 | During C0018, the threat actors used AvosLocker ransomware to encrypt files on the compromised network. |
| CampaignHomeLand Justice | During HomeLand Justice, threat actors used ROADSWEEP ransomware to encrypt files on targeted systems. |
| CampaignSharePoint ToolShell Exploitation | During SharePoint ToolShell Exploitation, threat actors deployed ransomware including 4L4MD4R and Warlock. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
