Techniques
Sample rules
Windows Spearphishing Attachment Connect To None MS Office Domain
- source: splunk
- technicques:
- T1566.001
Description
The following analytic identifies suspicious Office documents that connect to non-Microsoft Office domains. It leverages Sysmon EventCode 22 to detect processes like winword.exe or excel.exe making DNS queries to domains outside of *.office.com or *.office.net. This activity is significant as it may indicate a spearphishing attempt using malicious documents to download or connect to harmful content. If confirmed malicious, this could lead to unauthorized data access, malware infection, or further network compromise.
Detection logic
`sysmon` EventCode=22 Image IN ("*\\winword.exe","*\\excel.exe","*\\powerpnt.exe","*\\mspub.exe","*\\visio.exe","*\\wordpad.exe","*\\wordview.exe","*\\onenote.exe", "*\\onenotem.exe","*\\onenoteviewer.exe","*\\onenoteim.exe", "*\\msaccess.exe") AND NOT(QueryName IN ("*.office.com", "*.office.net"))
| stats count min(_time) as firstTime max(_time) as lastTime by answer answer_count dvc process_exec process_guid process_name query query_count reply_code_id signature signature_id src user_id vendor_product QueryName QueryResults QueryStatus
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `windows_spearphishing_attachment_connect_to_none_ms_office_domain_filter`