Adversaries may transfer tools or other files between systems in a compromised environment. Once brought into the victim environment (i.e., Ingress Tool Transfer) files may then be copied from one system to another to stage adversary tools or other files over the course of an operation. Adversaries may copy files between internal victim systems to support lateral movement using inherent file sharing protocols such as file sharing over SMB/Windows Admin Shares to connected network shares or with authenticated connections via Remote Desktop Protocol.(Citation: Unit42 LockerGoga 2019) Files can also be transferred using native or otherwise present tools on the victim system, such as scp, rsync, curl, sftp, and ftp. In some cases, adversaries may be able to leverage Web Services such as Dropbox or OneDrive to copy files from one machine to another via shared, automatically synced folders.(Citation: Dropbox Malware Sync)
Monitor scp, rsync, curl, sftp, or ftp processes initiating transfers to internal systems combined with file creation events in unusual directories. Correlate transfer activity with subsequent execution of those binaries.
Detect anomalous use of scp, rsync, curl, or third-party sync apps transferring executables into user directories. Correlate new file creation with immediate execution events.
Correlate suspicious file transfers over SMB or Admin$ shares with process creation events (e.g., cmd.exe, powershell.exe, certutil.exe) that do not align with normal administrative behavior. Detect remote file writes followed by execution of transferred binaries.
Network Intrusion Prevention
Use intrusion detection signatures to block traffic at network boundaries.
Filter Network Traffic
Employ network appliances and endpoint software to filter ingress, egress, and lateral network traffic. This includes protocol-based filtering, enforcing firewall rules, and blocking or restricting traffic based on predefined conditions to limit adversary movement and data exfiltration. This mitigation can be implemented through the following measures: Ingress Traffic Filtering: - Use Case: Configure network firewalls to allow traffic only from authorized IP addresses to public-facing servers. - Implementation: Limit SSH (port 22) and RDP (port 3389) traffic to specific IP ranges. Egress Traffic Filtering: - Use Case: Use firewalls or endpoint security software to block unauthorized outbound traffic to prevent data exfiltration and command-and-control (C2) communications. - Implementation: Block outbound traffic to known malicious IPs or regions where communication is unexpected. Protocol-Based Filtering: - Use Case: Restrict the use of specific protocols that are commonly abused by adversaries, such as SMB, RPC, or Telnet, based on business needs. - Implementation: Disable SMBv1 on endpoints to prevent exploits like EternalBlue. Network Segmentation: - Use Case: Create network segments for critical systems and restrict communication between segments unless explicitly authorized. - Implementation: Implement VLANs to isolate IoT devices or guest networks from core business systems. Application Layer Filtering: - Use Case: Use proxy servers or Web Application Firewalls (WAFs) to inspect and block malicious HTTP/S traffic. - Implementation: Configure a WAF to block SQL injection attempts or other web application exploitation techniques.