Detection rules › Splunk

ProtocolHandler.exe File Download (Sysmon)

Group by
_time, host
Source
github.com/anvilogic-forge/armory

ProtocolHandler.exe is a component of Microsoft Office and is typically used for accessing Microsoft Office documents from Outlook and Sharepoint. Adversaries can use ProtocolHandler.exe to download files. This use case detects executions of ProtocolHandler.exe followed by URLs in the command line. Allowlisting of expected Sharepoint domains is recommended to reduce false positives. LOLBINS/LOLBAS

MITRE ATT&CK coverage

TacticTechniques
Command & Control

References

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

id: '21901.38720'
title: ProtocolHandler.exe File Download
description: ProtocolHandler.exe is a component of Microsoft Office and is typically
  used for accessing Microsoft Office documents from Outlook and Sharepoint. Adversaries
  can use ProtocolHandler.exe to download files. This use case detects executions
  of ProtocolHandler.exe followed by URLs in the command line. Allowlisting of expected
  Sharepoint domains is recommended to reduce false positives. LOLBINS/LOLBAS
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<")
  "ProtocolHandler.exe" | regex process="(?i)ProtocolHandler\.exe\"?\s+\"?[A-Za-z0-9]{2,6}:\/\/"
  | table _time, host, user, signature_id, process, process_*, parent_process_path,
  parent_process_name | bin span=1s | stats values(*) as * by _time, host '
techniques:
- command-and-control:ingress tool transfer
technique_id: 
- T1105
data_category:
- Windows Sysmon
- Process command-line parameters
references:
- https://pentera.io/blog/the-lol-isnt-so-funny-when-it-bites-you-in-the-bas/
- https://lolbas-project.github.io/lolbas/OtherMSBinaries/ProtocolHandler/

Stages and Predicates

Stage 1: search

`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<") "ProtocolHandler.exe"

Stage 2: regex

| regex process="(?i)ProtocolHandler\.exe\"?\s+\"?[A-Za-z0-9]{2,6}:\/\/"

Stage 3: table

| table _time, host, user, signature_id, process, process_*, parent_process_path, parent_process_name

Stage 4: bucket

| bin span=1s

Stage 5: stats

| stats values(*) as * by _time, host

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
EventCodeeq
  • 1 corpus 241 (splunk 225, kusto 15, elastic 1)
field:"EventID" kind:eq value:"1"
processregex_match
  • "(?i)ProtocolHandler.exe\"?\s+\"?[A-Za-z0-9]{2,6}:\/\/" corpus 3 (splunk 3)
field:"CommandLine" kind:regex_match

Search terms

These SPL tokens match against raw event text.

StageTerm
1"<EventID>1<"
1"ProtocolHandler.exe"