Meterpreter or Cobalt Strike Getsystem Service Installation - Security

Severity: high
Author: Teymur Kheirkhabarov, Ecco, Florian Roth (Nextron Systems)
Source: upstream

Detects the use of getsystem Meterpreter/Cobalt Strike command by detecting a specific service installation

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1134.001` Access Token Manipulation: Token Impersonation/Theft, `T1134.002` Access Token Manipulation: Create Process with Token
Defense Evasion	`T1134.001` Access Token Manipulation: Token Impersonation/Theft, `T1134.002` Access Token Manipulation: Create Process with Token

Event coverage

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

Stages and Predicates

Stage 1: `selection_eid`

Stage 2: `1 of selection_cli_cmd`

or:
ServiceFileName|contains: '%COMSPEC%'
ServiceFileName|contains: cmd
ServiceFileName|contains: '/c'
ServiceFileName|contains: '\pipe\'
ServiceFileName|contains: echo

Stage 3: `1 of selection_cli_rundll`

ServiceFileName|contains: '.dll,a'
ServiceFileName|contains: '/p:'
ServiceFileName|contains: rundll32

Stage 4: `1 of selection_cli_share`

ServiceFileName|startswith: '\\\\127.0.0.1\\ADMIN$\'

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
`ServiceFileName`	match	`%COMSPEC%` corpus 2 (sigma 2) `.dll,a` `/c` corpus 3 (sigma 3) `/p:` `\pipe\` `cmd` corpus 5 (sigma 5) `echo` `rundll32` corpus 2 (sigma 2)
`ServiceFileName`	starts_with	`\\\\127.0.0.1\\ADMIN$\`

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)