Svchost spawning Cmd

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Identifies a suspicious parent child process relationship with cmd.exe descending from svchost.exe

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: low

Risk score: 21

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Execution
  • has_guide

Version: 101 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 8.5.0

Rule authors: Elastic

Rule license: Elastic License v2

Investigation guide

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## Triage and analysis

### Investigating Svchost spawning Cmd

The Service Host process (SvcHost) is a system process that can host one, or multiple, Windows services in the Windows
NT family of operating systems. Note that `Svchost.exe` is reserved for use by the operating system and should not be
used by non-Windows services.

This rule looks for the creation of the `cmd.exe` process with `svchost.exe` as its parent process. This is an unusual
behavior that can indicate the masquerading of a malicious process as `svchost.exe` or exploitation for privilege
escalation.

#### Possible investigation steps

- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Investigate any abnormal behavior by the subject process such as network connections, registry or file modifications,
and any spawned child processes.
- Retrieve the process executable and determine if it is malicious:
  - Use a private sandboxed malware analysis system to perform analysis.
    - Observe and collect information about the following activities:
      - Attempts to contact external domains and addresses.
      - File and registry access, modification, and creation activities.
      - Service creation and launch activities.
      - Scheduled task creation.
  - Use the PowerShell Get-FileHash cmdlet to get the files' SHA-256 hash values.
    - Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.

### False positive analysis

- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.

### Response and remediation

- Initiate the incident response process based on the outcome of the triage.
- Isolate the involved host to prevent further post-compromise behavior.
- If the triage identified malware, search the environment for additional compromised hosts.
  - Implement temporary network rules, procedures, and segmentation to contain the malware.
  - Stop suspicious processes.
  - Immediately block the identified indicators of compromise (IoCs).
  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that
  attackers could use to reinfect the system.
- Remove and block malicious artifacts identified during triage.
- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
malware components.
- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
mean time to respond (MTTR).

Rule query

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process where event.type == "start" and process.parent.name :
"svchost.exe" and process.name : "cmd.exe" and not process.args :
("??:\\Program Files\\Npcap\\CheckStatus.bat?", "?:\\Program
Files\\Npcap\\CheckStatus.bat", "\\system32\\cleanmgr.exe",
"?:\\Windows\\system32\\silcollector.cmd",
"\\system32\\AppHostRegistrationVerifier.exe",
"\\system32\\ServerManagerLauncher.exe", "dir",
"?:\\Program Files\\*", "?:\\Program Files (x86)\\*",
"?:\\Windows\\LSDeployment\\Lspush.exe",
"(x86)\\FMAuditOnsite\\watchdog.bat",
"?:\\ProgramData\\chocolatey\\bin\\choco-upgrade-all.bat",
"Files\\Npcap\\CheckStatus.bat") and /* very noisy pattern - bat
or cmd script executed via scheduled tasks */ not
(process.parent.args : "netsvcs" and process.args : ("?:\\*.bat",
"?:\\*.cmd"))

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 101 (8.5.0 release)
  • Updated query, changed from:

    process where event.type == "start" and process.parent.name :
    "svchost.exe" and process.name : "cmd.exe" and not
    (process.pe.original_file_name : "cmd.exe" and process.args : (
    "??:\\Program Files\\Npcap\\CheckStatus.bat?", "?:\\Program
    Files\\Npcap\\CheckStatus.bat", "\\system32\\cleanmgr.exe",
    "?:\\Windows\\system32\\silcollector.cmd",
    "\\system32\\AppHostRegistrationVerifier.exe",
    "\\system32\\ServerManagerLauncher.exe"))
Version 14 (8.4.0 release)
  • Updated query, changed from:

    process where event.type == "start" and process.parent.name :
    "svchost.exe" and process.name : "cmd.exe" and not
    (process.pe.original_file_name : "cmd.exe" and process.args : (
    "??:\\Program Files\\Npcap\\CheckStatus.bat?", "?:\\Program
    Files\\Npcap\\CheckStatus.bat", "\\system32\\cleanmgr.exe",
    "?:\\Windows\\system32\\silcollector.cmd",
    "\\system32\\AppHostRegistrationVerifier.exe",
    "\\system32\\ServerManagerLauncher.exe"))
Version 12 (8.3.0 release)
  • Formatting only
Version 10 (8.2.0 release)
  • Updated query, changed from:

    process where event.type in ("start", "process_started") and
    process.parent.name : "svchost.exe" and process.name : "cmd.exe" and
    not (process.pe.original_file_name == "Cmd.Exe" and process.args :
    "?:\\Program Files\\Npcap\\CheckStatus.bat??")
Version 8 (7.13.0 release)
  • Updated query, changed from:

    event.category:process and event.type:(start or process_started) and
    process.parent.name:svchost.exe and process.name:cmd.exe
Version 7 (7.12.0 release)
  • Formatting only
Version 6 (7.11.2 release)
  • Formatting only
Version 5 (7.10.0 release)
  • Formatting only
Version 4 (7.9.1 release)
  • Formatting only
Version 3 (7.9.0 release)
  • Updated query, changed from:

    process.parent.name:svchost.exe and process.name:cmd.exe
Version 2 (7.7.0 release)
  • Formatting only