Windows: Command-Line Use of ms-appinstaller Protocol Handler for File Downloads

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule flags Windows process command lines that invoke the ms-appinstaller protocol handler with a source parameter containing an http URL. Attackers can use AppInstaller.EXE via protocol invocation to fetch remote content and store it in an AppInstaller cache location. The detection relies on process creation telemetry and matches the presence of both ms-appinstaller://?source= and http in the command line.

Reporting behind it

Related detections9 linkedT1218 — drag to rearrange

Suspicious Cabinet Extraction of Masqueraded vstm Archive via extrac32

Malicious DLL Execution via Wuauclt Update Handler (via process_creation)

Malicious aspnet_compiler.exe Injection Host Spawned by PowerShell via process_creation

Malicious regsvcs LOLBin Loading Ransomware DLL from UNC Path

Suspicious RegAsm or RegSvcs Spawned by Script Host (via process_creation)

Suspicious Extexport DLL Side-Loading Execution

Malicious ClickFix Execution Chain Spawning MSHTA via Pcalua on EtherRAT Infection

Suspicious TALONITE Certutil LOLBIN Decode and Download Abuse (via process_creation)

Suspicious Renamed git Binary gcmd.exe Execution (via process_creation)

Windows: Command-Line Use of ms-appinstaller Protocol Handler for File Downloads

Pivot detection · T1218 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-command-line-use-of-ms-appinstaller-protocol-handler-for-file-downloads-180c7c5c

title: "Windows: Command-Line Use of ms-appinstaller Protocol Handler for File Downloads"
id: 281d0f90-ee96-46f6-ba90-938f0de5b9c7
related:
  - id: 7cff77e1-9663-46a3-8260-17f2e1aa9d0a
    type: derived
  - id: 180c7c5c-d64b-4a63-86e9-68910451bc8b
    type: derived
status: test
description: This rule flags Windows process command lines that invoke the ms-appinstaller protocol handler with a source parameter containing an http URL. Attackers can use AppInstaller.EXE via protocol invocation to fetch remote content and store it in an AppInstaller cache location. The detection relies on process creation telemetry and matches the presence of both ms-appinstaller://?source= and http in the command line.
references:
  - https://lolbas-project.github.io/lolbas/Binaries/AppInstaller/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_ms_appinstaller_download.yml
author: Nasreddine Bencherchali (Nextron Systems), Swachchhanda Shrawan Poudel, Huntrule Team
date: 2023-11-09
tags:
  - attack.execution
  - attack.stealth
  - attack.t1218
logsource:
  category: process_creation
  product: windows
detection:
  selection:
    CommandLine|contains|all:
      - ms-appinstaller://?source=
      - http
  condition: selection
falsepositives:
  - Unknown
level: medium
license: DRL-1.1

Convert

This rule as a query you can run. Uses no unlock credit.

SplunkSPL