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detectionlint / library / sigma

Obfuscated PowerShell MSI Install via WindowsInstaller COM

sigmaDRL-1.1from SigmaHQ/sigma

Detects the execution of obfuscated PowerShell commands that attempt to install MSI packages via the Windows Installer COM object (`WindowsInstaller.Installer`). The technique involves manipulating strings to hide functionality, such as constructing class names using string insertion (e.g., 'indowsInstaller.Installer'.Insert(0,'W')) and correcting malformed URLs (e.g., converting 'htps://' to 'https://') at runtime. This behavior is commonly associated with malware loaders or droppers that aim to bypass static detection by hiding intent in runtime-generated strings and using legitimate tools for code execution. The use of `InstallProduct` and COM object creation, particularly combined with hidden window execution and suppressed UI, indicates an attempt to install software (likely malicious) without user interaction.

02
quality70
fp risk—
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