Detect Installer Packages in Microsoft Sentinel
Adversaries may establish persistence and elevate privileges by using an installer package to execute malicious content. Installer packages are setup utilities for applications bundled with an installer utility and can be distributed through legitimate channels. Malicious code can be embedded within installer packages to create backdoors and establish persistence. Installer utilities such as msiexec.exe (Windows MSI), macOS pkgutil, and Linux dpkg/rpm allow adversaries to run pre-install and post-install scripts. These scripts can execute arbitrary code with elevated privileges during the installation process. Additionally, malicious code within the installer can establish persistence by deploying backdoors as scheduled tasks, services, or startup items.
MITRE ATT&CK
- Tactic
- Privilege Escalation Persistence
- Technique
- T1546 Event Triggered Execution
- Sub-technique
- T1546.016 Installer Packages
- Canonical reference
- https://attack.mitre.org/techniques/T1546/016/
KQL Detection Query
let MsiScriptPatterns = dynamic([
"powershell", "cmd.exe", "wscript", "cscript", "mshta",
"certutil", "bitsadmin", "Invoke-WebRequest", "DownloadString",
"Net.WebClient", "curl", "wget"
]);
let InstallerChildren = DeviceProcessEvents
| where Timestamp > ago(24h)
| where InitiatingProcessFileName in~ ("msiexec.exe", "installer", "pkgutil", "dpkg", "rpm", "yum", "apt")
| where FileName in~ (
"powershell.exe", "pwsh.exe", "cmd.exe", "wscript.exe", "cscript.exe",
"mshta.exe", "certutil.exe", "bitsadmin.exe", "bash", "sh", "python3", "python"
)
| extend SuspiciousCommand = ProcessCommandLine has_any (MsiScriptPatterns)
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine,
InitiatingProcessFileName, SuspiciousCommand;
let MsiDownloadIndicators = DeviceNetworkEvents
| where Timestamp > ago(24h)
| where InitiatingProcessFileName in~ ("msiexec.exe", "installer")
| where RemoteIPType == "Public"
| project NetTime=Timestamp, DeviceName, AccountName, RemoteIP, RemotePort, InitiatingProcessFileName;
union (InstallerChildren | extend EventType="INSTALLER_CHILD_PROCESS"),
(MsiDownloadIndicators | extend EventType="INSTALLER_NETWORK_ACTIVITY")
| sort by Timestamp desc, NetTime descDetects potentially malicious activity within installer package execution by monitoring for: (1) installer processes spawning scripting engines or LOLBins (msiexec.exe launching powershell.exe, cmd.exe with suspicious arguments), (2) installer processes making unexpected outbound network connections to external IPs (legitimate installers rarely download from the internet directly without a dedicated downloader process).
Data Sources
Required Tables
False Positives & Tuning
- Legitimate software installers that download additional components during installation (e.g., Visual Studio, Adobe products, game installers)
- Package managers (npm, pip, cargo) that run pre/post-install scripts as part of package installation
- Enterprise software deployment tools (SCCM, Intune, Munki, Chocolatey) that execute scripts as part of managed software installation
- Development toolchains that compile code or configure environments during installation via shell scripts
Other platforms for T1546.016
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1MSI Custom Action Spawning PowerShell
Expected signal: Process creation for msiexec.exe. Subsequent process creation for powershell.exe. The parent-child relationship (msiexec -> powershell) combined with the powershell command line arguments is the detection trigger.
- Test 2Package Manager Post-Install Script with Network Call
Expected signal: Process creation for pip install. Child process for python executing setup.py post-install hook. Child process for curl with the callback URL. The pip->python->curl chain is the detection signal.
- Test 3MSI Silent Installation with Custom Action Tracking
Expected signal: Process creation for msiexec.exe or cmd.exe spawned from installer context. File creation for custom_action_test.txt. Windows Installer Application event log entries for custom action execution.
References (5)
- https://attack.mitre.org/techniques/T1546/016/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1546.016/T1546.016.md
- https://docs.microsoft.com/en-us/windows/win32/msi/custom-actions
- https://arstechnica.com/information-technology/2022/01/researchers-find-hundreds-of-compromised-npm-packages-stealing-data/
- https://unit42.paloaltonetworks.com/atoms/supply-chain-compromise/
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