Service Installed By Unusual Client - Security

Severity: high
Author: Tim Rauch (Nextron Systems), Elastic (idea)
Source: upstream

Detects a service installed by a client which has PID 0 or whose parent has PID 0

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1543` Create or Modify System Process
Privilege Escalation	`T1543` Create or Modify System Process

Event coverage

Provider	Event ID	Title
Security-Auditing	4697	A service was installed in the system.

Stages and Predicates

Stage 1: `all of selection_eid`

Stage 2: `all of selection_pid`

or:
ClientProcessId: 0
ParentProcessId: 0

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
`ClientProcessId`	eq	`0` corpus 2 (sigma 1, elastic 1)
`ParentProcessId`	eq	`0` corpus 2 (sigma 1, elastic 1)

Neighbors

Stricter alternatives (narrower than this rule)

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

Windows Service Installed via an Unusual Client [elastic] (cross-vendor) (adds 5 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation Via Use Rundll32 - Security [sigma] (adds 5 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation VAR++ LAUNCHER OBFUSCATION - Security [sigma] (adds 5 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation VAR+ Launcher - Security [sigma] (adds 4 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation COMPRESS OBFUSCATION - Security [sigma] (adds 4 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation RUNDLL LAUNCHER - Security [sigma] (adds 4 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation Via Use MSHTA - Security [sigma] (adds 4 filters) (first-stage match only; downstream stages may differ)
Metasploit Or Impacket Service Installation Via SMB PsExec [sigma] (adds 4 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation CLIP+ Launcher - Security [sigma] (adds 3 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation Via Stdin - Security [sigma] (adds 3 filters) (first-stage match only; downstream stages may differ)
HybridConnectionManager Service Installation [sigma] (adds 2 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation STDIN+ Launcher - Security [sigma] (adds 2 filters) (first-stage match only; downstream stages may differ)
Invoke-Obfuscation Via Use Clip - Security [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)
Credential Dumping Tools Service Execution - Security [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)
Windows Pcap Drivers [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)
PowerShell Scripts Installed as Services - Security [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)
Remote Access Tool Services Have Been Installed - Security [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)
Tap Driver Installation - Security [sigma] (adds 1 filter) (first-stage match only; downstream stages may differ)