Techniques
Sample rules
Cisco NVM - Rundll32 Abuse of MSHTML.DLL for Payload Download
- source: splunk
- technicques:
- T1218.005
Description
This analytic detects suspicious use of rundll32.exe in combination with mshtml.dll and the export RunHTMLApplication.
This behavior is often observed in malware to execute JavaScript or VBScript in memory, enabling payload staging or
bypassing script execution policies and bypassing the usage of the “mshta.exe” binary.
The detection leverages Cisco Network Visibility Module telemetry which offers network flow activity
along with process information such as command-line arguments
If confirmed malicious, this activity may indicate initial access or payload download.
Detection logic
`cisco_network_visibility_module_flowdata`
process_name = "rundll32.exe"
process_arguments = "*mshtml*"
process_arguments IN ("*135*", "*RunHTMLApplication*")
| 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___rundll32_abuse_of_mshtml_dll_for_payload_download_filter`