Adversaries may clear Windows Event Logs to hide the activity of an intrusion. Windows Event Logs are a record of a computer's alerts and notifications. There are three system-defined sources of events: System, Application, and Security, with five event types: Error, Warning, Information, Success Audit, and Failure Audit. With administrator privileges, the event logs can be cleared with the following utility commands: * `wevtutil cl system` * `wevtutil cl application` * `wevtutil cl security` These logs may also be cleared through other mechanisms, such as the event viewer GUI or PowerShell. For example, adversaries may use the PowerShell command `Remove-EventLog -LogName Security` to delete the Security EventLog and after reboot, disable future logging. Note: events may still be generated and logged in the .evtx file between the time the command is run and the reboot.(Citation: disable_win_evt_logging) Adversaries may also attempt to clear logs by directly deleting the stored log files within `C:\Windows\System32\winevt\logs\`.
Detects behavioral sequence where an adversary gains elevated privileges and clears event logs using native binaries (e.g., wevtutil), PowerShell, or direct file deletion of .evtx files.
Restrict File and Directory Permissions
Restricting file and directory permissions involves setting access controls at the file system level to limit which users, groups, or processes can read, write, or execute files. By configuring permissions appropriately, organizations can reduce the attack surface for adversaries seeking to access sensitive data, plant malicious code, or tamper with system files. Enforce Least Privilege Permissions: - Remove unnecessary write permissions on sensitive files and directories. - Use file ownership and groups to control access for specific roles. Example (Windows): Right-click the shared folder → Properties → Security tab → Adjust permissions for NTFS ACLs. Harden File Shares: - Disable anonymous access to shared folders. - Enforce NTFS permissions for shared folders on Windows. Example: Set permissions to restrict write access to critical files, such as system executables (e.g., `/bin` or `/sbin` on Linux). Use tools like `chown` and `chmod` to assign file ownership and limit access. On Linux, apply: `chmod 750 /etc/sensitive.conf` `chown root:admin /etc/sensitive.conf` File Integrity Monitoring (FIM): - Use tools like Tripwire, Wazuh, or OSSEC to monitor changes to critical file permissions. Audit File System Access: - Enable auditing to track permission changes or unauthorized access attempts. - Use auditd (Linux) or Event Viewer (Windows) to log activities. Restrict Startup Directories: - Configure permissions to prevent unauthorized writes to directories like `C:\ProgramData\Microsoft\Windows\Start Menu`. Example: Restrict write access to critical directories like `/etc/`, `/usr/local/`, and Windows directories such as `C:\Windows\System32`. - On Windows, use icacls to modify permissions: `icacls "C:\Windows\System32" /inheritance:r /grant:r SYSTEM:(OI)(CI)F` - On Linux, monitor permissions using tools like `lsattr` or `auditd`.
Remote Data Storage
Remote Data Storage focuses on moving critical data, such as security logs and sensitive files, to secure, off-host locations to minimize unauthorized access, tampering, or destruction by adversaries. By leveraging remote storage solutions, organizations enhance the protection of forensic evidence, sensitive information, and monitoring data. This mitigation can be implemented through the following measures: Centralized Log Management: - Configure endpoints to forward security logs to a centralized log collector or SIEM. - Use tools like Splunk Graylog, or Security Onion to aggregate and store logs. - Example command (Linux): `sudo auditd | tee /var/log/audit/audit.log | nc <remote-log-server> 514` Remote File Storage Solutions: - Utilize cloud storage solutions like AWS S3, Google Cloud Storage, or Azure Blob Storage for sensitive data. - Ensure proper encryption at rest and access control policies (IAM roles, ACLs). Intrusion Detection Log Forwarding: - Forward logs from IDS/IPS systems (e.g., Zeek/Suricata) to a remote security information system. - Example for Suricata log forwarding: `outputs: - type: syslog protocol: tls address: <remote-syslog-server>` Immutable Backup Configurations: - Enable immutable storage settings for backups to prevent adversaries from modifying or deleting data. - Example: AWS S3 Object Lock. Data Encryption: - Ensure encryption for sensitive data using AES-256 at rest and TLS 1.2+ for data in transit. Tools: OpenSSL, BitLocker, LUKS for Linux.
Encrypt Sensitive Information
Protect sensitive information at rest, in transit, and during processing by using strong encryption algorithms. Encryption ensures the confidentiality and integrity of data, preventing unauthorized access or tampering. This mitigation can be implemented through the following measures: Encrypt Data at Rest: - Use Case: Use full-disk encryption or file-level encryption to secure sensitive data stored on devices. - Implementation: Implement BitLocker for Windows systems or FileVault for macOS devices to encrypt hard drives. Encrypt Data in Transit: - Use Case: Use secure communication protocols (e.g., TLS, HTTPS) to encrypt sensitive data as it travels over networks. - Implementation: Enable HTTPS for all web applications and configure mail servers to enforce STARTTLS for email encryption. Encrypt Backups: - Use Case: Ensure that backup data is encrypted both during storage and transfer to prevent unauthorized access. - Implementation: Encrypt cloud backups using AES-256 before uploading them to Amazon S3 or Google Cloud. Encrypt Application Secrets: - Use Case: Store sensitive credentials, API keys, and configuration files in encrypted vaults. - Implementation: Use HashiCorp Vault or AWS Secrets Manager to manage and encrypt secrets. Database Encryption: - Use Case: Enable Transparent Data Encryption (TDE) or column-level encryption in database management systems. - Implementation: Use MySQL’s built-in encryption features to encrypt sensitive database fields such as social security numbers.