Detection rules › Splunk
Office Binary Download Remote File (Windows Event Log)
Unsanitized file validation leads to Malicious payload download via Office binaries. Attackers may leverage these binaries in order to download payloads and bypass defenses
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Command & Control |
References
Telemetry coverage
| Provider | Record / event type |
|---|---|
| Security-Auditing | Event ID 4688: A new process has been created. |
Rule body
id: '6590.7620'
title: Office Binary Download Remote File
description: 'Unsanitized file validation leads to Malicious payload download via
Office binaries. Attackers may leverage these binaries in order to download payloads
and bypass defenses. -- Threat Actor Association: Evilnum, FIN11, NewsPenguin -
Software Association: Clop, Qakbot/Qbot -- Living Off the Land Binary and Scripts
(LOLBAS) (LOLBIN)'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process) ("POWERPNT.EXE" OR "WINWORD.EXE" OR "EXCEL.EXE"
OR "ONENOTE.EXE" OR "mspub.exe" OR "outlook.exe" OR "msaccess.exe") | table _time,
host, user user, process, process_*, parent_* | bin span=1s | stats values(*) as
* by _time, host | where match(process, "(?i)\w?\wtps?\:(\/\/|\x5c\x5c)") '
techniques:
- command-and-control:ingress tool transfer
technique_id:
- T1105
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://medium.com/@reegun/unsanitized-file-validation-leads-to-malicious-payload-download-via-office-binaries-202d02db7191
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process) ("POWERPNT.EXE" OR "WINWORD.EXE" OR "EXCEL.EXE" OR "ONENOTE.EXE" OR "mspub.exe" OR "outlook.exe" OR "msaccess.exe")
Stage 2: table
| table _time, host, user user, process, process_*, parent_*
Stage 3: bucket
| bin span=1s
Stage 4: stats
| stats values(*) as * by _time, host
Stage 5: where
| where match(process, "(?i)\w?\wtps?\:(\/\/|\x5c\x5c)")
Indicators
These rows show field, operator, and value matches.
| Field | Kind | Values | Search |
|---|---|---|---|
EventCode | eq |
| field:"EventID" kind:eq value:"4688" |
process | regex_match |
| field:"CommandLine" kind:regex_match |
Search terms
These SPL tokens match against raw event text.
| Stage | Term |
|---|---|
| 1 | "<EventID>4688<" |
| 1 | "POWERPNT.EXE" |
| 1 | "WINWORD.EXE" |
| 1 | "EXCEL.EXE" |
| 1 | "ONENOTE.EXE" |
| 1 | "mspub.exe" |
| 1 | "outlook.exe" |
| 1 | "msaccess.exe" |