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Detection rules › Sigma

PowerShell Script With File Upload Capabilities

Severity
low
Author
frack113
Source
upstream

Detects PowerShell scripts leveraging the "Invoke-WebRequest" cmdlet to send data via either "PUT" or "POST" method.

MITRE ATT&CK coverage

TacticTechniques
ExfiltrationT1020 Automated Exfiltration

Event coverage

ProviderEvent IDTitle
PowerShell4104Creating Scriptblock text (MessageNumber of MessageTotal).

Stages and Predicates

Stage 1: all of selection_cmdlet

or:
ScriptBlockText|contains: Invoke-RestMethod
ScriptBlockText|contains: Invoke-WebRequest
ScriptBlockText|contains: 'irm '
ScriptBlockText|contains: 'iwr '

Stage 2: all of selection_flag

or:
ScriptBlockText|contains: '-Method ''POST'''
ScriptBlockText|contains: '-Method ''PUT'''
ScriptBlockText|contains: '-Method POST'
ScriptBlockText|contains: '-Method PUT'
ScriptBlockText|contains: '-Method "POST"'
ScriptBlockText|contains: '-Method "PUT"'

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.

FieldKindValues
ScriptBlockTextmatch
  • -Method "POST"
  • -Method "PUT"
  • -Method 'POST'
  • -Method 'PUT'
  • -Method POST
  • -Method PUT
  • Invoke-RestMethod corpus 3 (sigma 3)
  • Invoke-WebRequest corpus 3 (sigma 3)
  • irm
  • iwr corpus 3 (sigma 3)

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.