Adversaries may clear or remove evidence of malicious network connections in order to clean up traces of their operations. Configuration settings as well as various artifacts that highlight connection history may be created on a system and/or in application logs from behaviors that require network connections, such as Remote Services or External Remote Services. Defenders may use these artifacts to monitor or otherwise analyze network connections created by adversaries.
Network connection history may be stored in various locations. For example, RDP connection history may be stored in Windows Registry values under (Citation: Microsoft RDP Removal):
Windows may also store information about recent RDP connections in files such as <code>C:\Users\%username%\Documents\Default.rdp</code> and C:\Users\%username%\AppData\Local\Microsoft\Terminal Server Client\Cache\.(Citation: Moran RDPieces) Similarly, macOS and Linux hosts may store information highlighting connection history in system logs (such as those stored in /Library/Logs and/or /var/log/).(Citation: Apple Culprit Access)(Citation: FreeDesktop Journal)(Citation: Apple Unified Log Analysis Remote Login and Screen Sharing)
Malicious network connections may also require changes to third-party applications or network configuration settings, such as Disable or Modify System Firewall or tampering to enable Proxy. Adversaries may delete or modify this data to conceal indicators and/or impede defensive analysis.
Behavioral Detection of Network History and Configuration Tampering
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:
sudo auditd | tee /var/log/audit/audit.log | nc <remote-log-server> 514Remote File Storage Solutions:
Intrusion Detection Log Forwarding:
Immutable Backup Configurations:
Data Encryption:
Restrict Registry Permissions: Restricting registry permissions involves configuring access control settings for sensitive registry keys and hives to ensure that only authorized users or processes can make modifications. By limiting access, organizations can prevent unauthorized changes that adversaries might use for persistence, privilege escalation, or defense evasion. This mitigation can be implemented through the following measures:
Review and Adjust Permissions on Critical Keys
Run, RunOnce, and Services to ensure only authorized users have write access.icacls or PowerShell to automate permission adjustments.Enable Registry Auditing
auditpol /set /subcategory:"Registry" /success:enable /failure:enableProtect Credential-Related Hives
SAM,SECURITY, and SYSTEM to prevent credential dumping or other unauthorized access.Restrict Registry Editor Usage
Deploy Baseline Configuration Tools
Tools for Implementation
Registry Permission Tools:
Set-ItemProperty -Path "HKLM:\Software\Microsoft\Windows\CurrentVersion\Run" -Name "KeyName" -Value "Value"Monitoring Tools:
Policy Management Tools: