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 | T1105 Ingress Tool Transfer |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
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
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.
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | 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" |