CobaltStrike Service Installations - Security

Severity: high
Author: Florian Roth (Nextron Systems), Wojciech Lesicki
Source: upstream

Detects known malicious service installs that appear in cases in which a Cobalt Strike beacon elevates privileges or lateral movement

MITRE ATT&CK coverage

Tactic	Techniques
Execution	`T1569.002` System Services: Service Execution
Persistence	`T1543.003` Create or Modify System Process: Windows Service
Privilege Escalation	`T1543.003` Create or Modify System Process: Windows Service
Lateral Movement	`T1021.002` Remote Services: SMB/Windows Admin Shares

Event coverage

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

Stages and Predicates

Stage 1: `event_id`

Stage 2: `1 of selection1`

ServiceFileName|contains: .exe
ServiceFileName|contains: 'ADMIN$'

Stage 3: `1 of selection2`

ServiceFileName|contains: '%COMSPEC%'
ServiceFileName|contains: powershell
ServiceFileName|contains: start

Stage 4: `1 of selection3`

ServiceFileName|contains: 'powershell -nop -w hidden -encodedcommand'

Stage 5: `1 of selection4`

ServiceFileName|contains: 'IEX (New-Object Net.Webclient).DownloadString(''http://127.0.0.1:'

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) `.exe` `ADMIN$` `IEX (New-Object Net.Webclient).DownloadString('http://127.0.0.1:` `powershell` corpus 4 (sigma 4) `powershell -nop -w hidden -encodedcommand` `start`

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)