Unusual Child Process from a System Virtual Process

Identifies a suspicious child process of the Windows virtual system process, which could indicate code injection.

Elastic rule (View on GitHub)

 1[metadata]
 2creation_date = "2020/08/19"
 3integration = ["endpoint", "windows"]
 4maturity = "production"
 5min_stack_comments = "New fields added: required_fields, related_integrations, setup"
 6min_stack_version = "8.3.0"
 7updated_date = "2023/06/22"
 8
 9[rule]
10author = ["Elastic"]
11description = "Identifies a suspicious child process of the Windows virtual system process, which could indicate code injection."
12from = "now-9m"
13index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*", "endgame-*"]
14language = "eql"
15license = "Elastic License v2"
16name = "Unusual Child Process from a System Virtual Process"
17note = """## Setup
18
19If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
20"""
21risk_score = 73
22rule_id = "de9bd7e0-49e9-4e92-a64d-53ade2e66af1"
23severity = "high"
24tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Defense Evasion", "Data Source: Elastic Endgame", "Data Source: Elastic Defend"]
25timestamp_override = "event.ingested"
26type = "eql"
27
28query = '''
29process where host.os.type == "windows" and event.type == "start" and
30  process.parent.pid == 4 and
31  not process.executable : ("Registry", "MemCompression", "?:\\Windows\\System32\\smss.exe")
32'''
33
34
35[[rule.threat]]
36framework = "MITRE ATT&CK"
37[[rule.threat.technique]]
38id = "T1055"
39name = "Process Injection"
40reference = "https://attack.mitre.org/techniques/T1055/"
41
42
43[rule.threat.tactic]
44id = "TA0005"
45name = "Defense Evasion"
46reference = "https://attack.mitre.org/tactics/TA0005/"

Setup

If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define event.ingested and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate event.ingested to @timestamp for this rule to work.

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