LoFP LoFP / rare cases may exist where these binaries are used by plugins or third-party extensions to initiate outbound communication. however, such behavior is extremely uncommon and should be investigated for potential injection or abuse.

Techniques

Sample rules

Cisco NVM - Non-Network Binary Making Network Connection

Description

This analytic detects network connections initiated by binaries that are not typically associated with network communication, such as ’notepad.exe’, ‘calc.exe’ or ‘write.exe’. It leverages Cisco Network Visibility Module logs to correlate network flow activity with process context, including command-line arguments, process path, and parent process information. These applications are normally used for locally and do not require outbound network access. When they do initiate such connections, it may indicate process hollowing, code injection, or proxy execution, where adversaries abuse a trusted process to mask malicious activity.

Detection logic

`cisco_network_visibility_module_flowdata`
process_name IN (
        "notepad.exe", "write.exe", "mspaint.exe", "calc.exe", 
        "addinutil.exe", "cmstp.exe", "dialer.exe", "eqnedt32.exe", "IMEWDBLD.exe"
        )
NOT dest IN (
        "10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "100.64.0.0/10", 
        "127.0.0.0/8", "169.254.0.0/16", "192.0.0.0/24", "192.0.0.0/29", "192.0.0.8/32", 
        "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32", "192.0.2.0/24", 
        "192.31.196.0/24", "192.52.193.0/24", "192.88.99.0/24", "224.0.0.0/4", "192.175.48.0/24", 
        "198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1"
        )

| stats count min(_time) as firstTime max(_time) as lastTime
        values(parent_process_arguments) as parent_process_arguments
        values(process_arguments) as process_arguments
        values(parent_process_hash) as parent_process_hash
        values(process_hash) as process_hash
        values(module_name_list) as module_name_list
        values(module_hash_list) as module_hash_list
        values(dest_port) as dest_port
        values(aliul) as additional_logged_in_users_list
        values(dest_hostname) as dest_hostname
        by src dest parent_process_path parent_process_integrity_level process_path process_name process_integrity_level process_id transport

| `security_content_ctime(firstTime)`

| `security_content_ctime(lastTime)`

| table
  parent_process_integrity_level parent_process_path parent_process_arguments parent_process_hash
  process_integrity_level process_path process_name process_arguments process_hash process_id
  additional_logged_in_users_list module_name_list module_hash_list
  src dest_hostname dest dest_port transport firstTime lastTime

| `cisco_nvm___non_network_binary_making_network_connection_filter`