Windows Process Creation: svchost.exe with msupdate/alg Service Flags
Alerts on svchost.exe started with specific -k command-line flags consistent with suspicious persistence activity.
FreeReviewedSigma · Critical · v5
- Product
- windows
- Category
- process_creation
- Author
- X__Junior (Nextron Systems) (SigmaHQ), DRL 1.1
- Published
- 2023-04-30
- Updated
- 2026-07-31
What it detects
Identifies Windows process creation events where an executable named svchost.exe is launched with specific trailing command-line flags associated with service-related execution. Attackers may use service-style host processes with crafted arguments to persist or execute malicious functionality while blending into legitimate Windows process naming. Detection relies on process creation telemetry capturing both the executable path and the full command line.
Reporting behind it
Changelog
v5- v5Candidate ingested via manual entry.2026-07-31
- v4Candidate ingested via manual entry.2026-07-31
- v3Candidate ingested via manual entry.2026-07-31
- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
windows-process-creation-svchost-exe-with-specific-k-flags-9f9cd389
title: "Windows Process Creation: svchost.exe with msupdate/alg Service Flags"
id: f12d4490-b0cb-43a4-b1a4-e129906c0387
status: test
description: Identifies Windows process creation events where an executable named svchost.exe is launched with specific trailing command-line flags associated with service-related execution. Attackers may use service-style host processes with crafted arguments to persist or execute malicious functionality while blending into legitimate Windows process naming. Detection relies on process creation telemetry capturing both the executable path and the full command line.
references:
- https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/cold-steel/NCSC-MAR-Cold-Steel.pdf
- https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2023/Malware/COLDSTEEL/proc_creation_win_malware_coldsteel_service_persistence.yml
author: X__Junior (Nextron Systems), Huntrule Team
date: 2023-04-30
tags:
- attack.persistence
- detection.emerging-threats
- attack.stealth
logsource:
category: process_creation
product: windows
detection:
selection:
Image|endswith: \svchost.exe
CommandLine|endswith:
- " -k msupdate"
- " -k msupdate2"
- " -k alg"
condition: selection
falsepositives:
- Unlikely
level: critical
license: DRL-1.1
related:
- id: 9f9cd389-cea0-4142-bf1a-a3fd424abedd
type: derived