Detection rules › Sigma

Outbound Network Connection Initiated By Script Interpreter

Severity
high
Author
frack113, Florian Roth (Nextron Systems)
Source
upstream

Detects a script interpreter wscript/cscript opening a network connection to a non-local network. Adversaries may use script to download malicious payloads.

MITRE ATT&CK coverage

TacticTechniques
Command & ControlT1105 Ingress Tool Transfer

Event coverage

ProviderEvent IDTitle
Sysmon3Network connection

Stages and Predicates

Stage 1: selection

or:
Image|endswith: '\cscript.exe'
Image|endswith: '\wscript.exe'
Initiated: true

Stage 2: not 1 of filter_main_*

or:
DestinationIp|cidr: '10.0.0.0/8'
DestinationIp|cidr: '127.0.0.0/8'
DestinationIp|cidr: '169.254.0.0/16'
DestinationIp|cidr: '172.16.0.0/12'
DestinationIp|cidr: '192.168.0.0/16'
DestinationIp|cidr: '20.0.0.0/11'
DestinationIp|cidr: '::1/128'
DestinationIp|cidr: 'fc00::/7'
DestinationIp|cidr: 'fe80::/10'

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
DestinationIpcidr_match
  • 10.0.0.0/8 corpus 12 (sigma 12)
  • 127.0.0.0/8 corpus 13 (sigma 13)
  • 169.254.0.0/16 corpus 12 (sigma 12)
  • 172.16.0.0/12 corpus 12 (sigma 12)
  • 192.168.0.0/16 corpus 12 (sigma 12)
  • 20.0.0.0/11
  • ::1/128 corpus 13 (sigma 13)
  • fc00::/7 corpus 12 (sigma 12)
  • fe80::/10 corpus 12 (sigma 12)
Imageends_with
  • \cscript.exe corpus 64 (sigma 64)
  • \wscript.exe corpus 64 (sigma 64)
Initiatedeq
  • true corpus 40 (sigma 40)

Neighbors

Stricter alternatives (narrower than this rule)

The rules below may be useful if you find the current rule is too noisy / lacks specificity.