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Detection rules › Sigma

Network Connection Initiated By PowerShell Process

Status
test
Severity
low
Log source
product windows, category network_connection
Author
Florian Roth (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects a network connection that was initiated from a PowerShell process. Often times malicious powershell scripts download additional payloads or communicate back to command and control channels via uncommon ports or IPs. Use this rule as a basis for hunting for anomalies.

MITRE ATT&CK coverage

TacticTechniques
ExecutionT1059.001 Command and Scripting Interpreter: PowerShell

Event coverage

ProviderEventTitle
SysmonEvent ID 3Network connection

Rule body yaml

title: Network Connection Initiated By PowerShell Process
id: 1f21ec3f-810d-4b0e-8045-322202e22b4b
status: test
description: |
    Detects a network connection that was initiated from a PowerShell process.
    Often times malicious powershell scripts download additional payloads or communicate back to command and control channels via uncommon ports or IPs.
    Use this rule as a basis for hunting for anomalies.
references:
    - https://www.youtube.com/watch?v=DLtJTxMWZ2o
author: Florian Roth (Nextron Systems)
date: 2017-03-13
modified: 2024-03-13
tags:
    - attack.execution
    - attack.t1059.001
    - detection.threat-hunting
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        Initiated: 'true'
    filter_main_local_ip:
        DestinationIp|cidr:
            - '127.0.0.0/8'
            - '10.0.0.0/8'
            - '169.254.0.0/16'  # link-local address
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '::1/128'  # IPv6 loopback
            - 'fe80::/10'  # IPv6 link-local addresses
            - 'fc00::/7'  # IPv6 private addresses
        User|contains: # covers many language settings
            - 'AUTHORI'
            - 'AUTORI'
    filter_main_msrange:
        DestinationIp|cidr:
            - '20.184.0.0/13'
            - '51.103.210.0/23'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Administrative scripts
    - Microsoft IP range
    - Additional filters are required. Adjust to your environment (e.g. extend filters with company's ip range')
level: low

Stages and Predicates

Stage 0: condition

selection and not 1 of filter_main_*

Stage 1: selection

selection:
    Image|endswith:
        - '\powershell.exe'
        - '\pwsh.exe'
    Initiated: 'true'

Stage 2: not filter_main_*

filter_main_local_ip:
    DestinationIp|cidr:
        - '127.0.0.0/8'
        - '10.0.0.0/8'
        - '169.254.0.0/16'
        - '172.16.0.0/12'
        - '192.168.0.0/16'
        - '::1/128'
        - 'fe80::/10'
        - 'fc00::/7'
    User|contains:
        - 'AUTHORI'
        - 'AUTORI'
filter_main_msrange:
    DestinationIp|cidr:
        - '20.184.0.0/13'
        - '51.103.210.0/23'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

FieldKindExcluded values
DestinationIpcidr_match10.0.0.0/8
DestinationIpcidr_match127.0.0.0/8
DestinationIpcidr_match169.254.0.0/16
DestinationIpcidr_match172.16.0.0/12
DestinationIpcidr_match192.168.0.0/16
DestinationIpcidr_match::1/128
DestinationIpcidr_matchfc00::/7
DestinationIpcidr_matchfe80::/10
UsermatchAUTHORI
UsermatchAUTORI
DestinationIpcidr_match20.184.0.0/13
DestinationIpcidr_match51.103.210.0/23

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
Imageends_with
  • \powershell.exe corpus 182 (sigma 182)
  • \pwsh.exe corpus 168 (sigma 168)
Initiatedeq
  • true corpus 50 (sigma 50)