Powershell MsXml COM Object

Severity: medium
Author: frack113, MatilJ
Source: upstream

Adversaries may abuse PowerShell commands and scripts for execution. PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. (Citation: TechNet PowerShell) Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1059.001` Command and Scripting Interpreter: PowerShell

Event coverage

Provider	Event ID	Title
PowerShell	4104	Creating Scriptblock text (MessageNumber of MessageTotal).

Stages and Predicates

Stage 1: `selection`

ScriptBlockText|contains: -ComObject
ScriptBlockText|contains: MsXml2.
ScriptBlockText|contains: New-Object
ScriptBlockText|contains: XmlHttp

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.

Field	Kind	Values
`ScriptBlockText`	match	`-ComObject` `MsXml2.` `New-Object` corpus 6 (sigma 6) `XmlHttp`

Neighbors

Broader alternatives (more inclusive than this rule)

These rules match a superset of what this rule catches. They cover the same events plus more. Use them if you want wider coverage and can absorb more false positives.

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Potential PowerShell Obfuscation via Character Array Reconstruction [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via Concatenated Dynamic Command Invocation [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via High Numeric Character Proportion [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential Dynamic IEX Reconstruction via Environment Variables [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Dynamic IEX Reconstruction via Method String Access [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
PowerShell Obfuscation via Negative Index String Reversal [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via Reverse Keywords [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via String Concatenation [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via String Reordering [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)
Potential PowerShell Obfuscation via Special Character Overuse [elastic] (cross-vendor) (drops 4 filters this rule applies) (first-stage match only; downstream stages may differ)