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) Adversaries may also encrypt virtual machines hosted on ESXi or other hypervisors.(Citation: Crowdstrike Hypervisor Jackpotting Pt 2 2021) 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 ESXi server login messages, or otherwise intimidate victims by sending ransom notes or other messages to connected printers (known as "print bombing").(Citation: NHS Digital Egregor Nov 2020)(Citation: Varonis) In cloud environments, storage objects within compromised accounts may also be encrypted.(Citation: Rhino S3 Ransomware Part 1) 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.(Citation: Halcyon AWS Ransomware 2025)
Behavior Prevention on Endpoint refers to the use of technologies and strategies to detect and block potentially malicious activities by analyzing the behavior of processes, files, API calls, and other endpoint events. Rather than relying solely on known signatures, this approach leverages heuristics, machine learning, and real-time monitoring to identify anomalous patterns indicative of an attack. This mitigation can be implemented through the following measures: Suspicious Process Behavior: - Implementation: Use Endpoint Detection and Response (EDR) tools to monitor and block processes exhibiting unusual behavior, such as privilege escalation attempts. - Use Case: An attacker uses a known vulnerability to spawn a privileged process from a user-level application. The endpoint tool detects the abnormal parent-child process relationship and blocks the action. Unauthorized File Access: - Implementation: Leverage Data Loss Prevention (DLP) or endpoint tools to block processes attempting to access sensitive files without proper authorization. - Use Case: A process tries to read or modify a sensitive file located in a restricted directory, such as /etc/shadow on Linux or the SAM registry hive on Windows. The endpoint tool identifies this anomalous behavior and prevents it. Abnormal API Calls: - Implementation: Implement runtime analysis tools to monitor API calls and block those associated with malicious activities. - Use Case: A process dynamically injects itself into another process to hijack its execution. The endpoint detects the abnormal use of APIs like `OpenProcess` and `WriteProcessMemory` and terminates the offending process. Exploit Prevention: - Implementation: Use behavioral exploit prevention tools to detect and block exploits attempting to gain unauthorized access. - Use Case: A buffer overflow exploit is launched against a vulnerable application. The endpoint detects the anomalous memory write operation and halts the process.
Data Backup involves taking and securely storing backups of data from end-user systems and critical servers. It ensures that data remains available in the event of system compromise, ransomware attacks, or other disruptions. Backup processes should include hardening backup systems, implementing secure storage solutions, and keeping backups isolated from the corporate network to prevent compromise during active incidents. This mitigation can be implemented through the following measures: Regular Backup Scheduling: - Use Case: Ensure timely and consistent backups of critical data. - Implementation: Schedule daily incremental backups and weekly full backups for all critical servers and systems. Immutable Backups: - Use Case: Protect backups from modification or deletion, even by attackers. - Implementation: Use write-once-read-many (WORM) storage for backups, preventing ransomware from encrypting or deleting backup files. Backup Encryption: - Use Case: Protect data integrity and confidentiality during transit and storage. - Implementation: Encrypt backups using strong encryption protocols (e.g., AES-256) before storing them in local, cloud, or remote locations. Offsite Backup Storage: - Use Case: Ensure data availability during physical disasters or onsite breaches. - Implementation: Use cloud-based solutions like AWS S3, Azure Backup, or physical offsite storage to maintain a copy of critical data. Backup Testing: - Use Case: Validate backup integrity and ensure recoverability. - Implementation: Regularly test data restoration processes to ensure that backups are not corrupted and can be recovered quickly.
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