Detection rules › Sigma

Rundll32 Internet Connection

Severity
medium
Author
Florian Roth (Nextron Systems)
Source
upstream

Detects a rundll32 that communicates with public IP addresses

MITRE ATT&CK coverage

TacticTechniques
Defense EvasionT1218.011 System Binary Proxy Execution: Rundll32

Event coverage

ProviderEvent IDTitle
Sysmon3Network connection

Stages and Predicates

Stage 1: selection

Image|endswith: '\rundll32.exe'
Initiated: true

Stage 2: not 1 of filter_main_*

or:
DestinationPort: 443
ParentImage: 'C:\Windows\System32\svchost.exe'
CommandLine|endswith: '\system32\PcaSvc.dll,PcaPatchSdbTask'
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: '20.0.0.0/8'
DestinationIp|cidr: '51.103.0.0/16'
DestinationIp|cidr: '51.104.0.0/16'
DestinationIp|cidr: '51.105.0.0/16'
DestinationIp|cidr: '::1/128'
DestinationIp|cidr: 'fc00::/7'
DestinationIp|cidr: 'fe80::/10'
SourceHostname|endswith: .internal.cloudapp.net

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
CommandLineends_with
  • \system32\PcaSvc.dll,PcaPatchSdbTask
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)
  • 20.0.0.0/8
  • 51.103.0.0/16 corpus 3 (sigma 3)
  • 51.104.0.0/16
  • 51.105.0.0/16
  • ::1/128 corpus 13 (sigma 13)
  • fc00::/7 corpus 12 (sigma 12)
  • fe80::/10 corpus 12 (sigma 12)
DestinationPorteq
  • 443 corpus 7 (sigma 7)
Imageends_with
  • \rundll32.exe corpus 76 (sigma 76)
Initiatedeq
  • true corpus 40 (sigma 40)
ParentImageeq
  • C:\Windows\System32\svchost.exe corpus 3 (sigma 3)
SourceHostnameends_with
  • .internal.cloudapp.net