Detection rules › Splunk
mshta.exe File Download (PowerShell)
mshta.exe is a Windows utility used for executing HTML applications and can be abused by adversaries to download files. This use case detects executions of mshta.exe with URLs in the command line. LOLBINS/LOLBAS
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1218.005 System Binary Proxy Execution: Mshta |
| Command & Control | T1105 Ingress Tool Transfer |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| PowerShell | Event ID 4104 | Creating Scriptblock text (MessageNumber of MessageTotal). |
Rule body yaml
id: '22128.39016'
title: mshta.exe File Download
description: 'mshta.exe is a Windows utility used for executing HTML applications
and can be abused by adversaries to download files. This use case detects executions
of mshta.exe with URLs in the command line. LOLBINS/LOLBAS -- Threat Actor Association:
LockBit'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR
"<EventID>4104<") "mshta.exe" | regex process="(?i)(http|ftp)s?:\/\/" | 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
- defense-evasion:system binary proxy execution:mshta
technique_id:
- T1105
- T1218.005
data_category:
- PowerShell logs
references:
- https://pentera.io/blog/the-lol-isnt-so-funny-when-it-bites-you-in-the-bas/
- https://lolbas-project.github.io/lolbas/Binaries/Mshta/
- https://www.falconguard.cz/post/top-10-lol-binaries-and-techniques-used-by-cyber-threat-actors
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_powershell` (TERM(EventCode=4104) OR "<EventID>4104<") "mshta.exe"
Stage 2: regex
| regex process="(?i)(http|ftp)s?:\/\/"
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
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>4104<" |
| 1 | "mshta.exe" |