Detection rules › Splunk

Windows Office Product Loading Taskschd DLL

Author
Teoderick Contreras, Splunk
Source
upstream

The following analytic detects an Office document creating a scheduled task, either through a macro VBA API or by loading taskschd.dll. This detection leverages Sysmon EventCode 7 to identify when Office applications load the taskschd.dll file. This activity is significant as it is a common technique used by malicious macro malware to establish persistence or initiate beaconing. If confirmed malicious, this could allow an attacker to maintain persistence, execute arbitrary commands, or schedule future malicious activities, posing a significant threat to the environment.

MITRE ATT&CK coverage

TacticTechniques
Initial AccessT1566.001 Phishing: Spearphishing Attachment

Event coverage

ProviderEvent IDTitle
Sysmon7Image loaded

Stages and Predicates

Stage 1: search

search EventCode=7 loaded_file_path="*\\taskschd.dll" process_name IN ("EQNEDT32.exe", "Graph.exe", "excel.exe", "msaccess.exe", "mspub.exe", "onenote.exe", "onenoteim.exe", "onenotem.exe", "outlook.exe", "powerpnt.exe", "visio.exe", "winproj.exe", "winword.exe")

Stage 2: fillnull

fillnull

Stage 3: stats

stats BY Image, ImageLoaded, dest, loaded_file, loaded_file_path, original_file_name, process_exec, process_guid, process_hash, process_id, process_name, process_path, service_dll_signature_exists, service_dll_signature_verified, signature, signature_id, user_id, vendor_product

Stage 4: search

search

Stage 5: search

search

Stage 6: search

search `macro`

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
EventCodeeq
  • 7 corpus 35 (splunk 35)
loaded_file_patheq
  • "*\\taskschd.dll" corpus 2 (splunk 2)
process_namein
  • "EQNEDT32.exe" corpus 5 (splunk 5)
  • "Graph.exe" corpus 5 (splunk 5)
  • "excel.exe" corpus 5 (splunk 5)
  • "msaccess.exe" corpus 5 (splunk 5)
  • "mspub.exe" corpus 5 (splunk 5)
  • "onenote.exe" corpus 5 (splunk 5)
  • "onenoteim.exe" corpus 5 (splunk 5)
  • "onenotem.exe" corpus 5 (splunk 5)
  • "outlook.exe" corpus 5 (splunk 5)
  • "powerpnt.exe" corpus 5 (splunk 5)
  • "visio.exe" corpus 5 (splunk 5)
  • "winproj.exe" corpus 5 (splunk 5)
  • "winword.exe" corpus 5 (splunk 5)

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.