Samirbous
8e0ae64a04
* added Whoami Process Activity * Update discovery_whoami_command_activity.toml Co-authored-by: Colson Wilhoit <48036388+DefSecSentinel@users.noreply.github.com>
111 lines
4.9 KiB
TOML
111 lines
4.9 KiB
TOML
[metadata]
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creation_date = "2020/02/18"
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maturity = "production"
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updated_date = "2022/08/03"
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[rule]
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author = ["Elastic"]
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description = """
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Identifies suspicious use of whoami.exe which displays user, group, and privileges information for the user who is currently logged
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on to the local system.
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"""
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false_positives = [
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"""
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Some normal use of this program, at varying levels of frequency, may originate from scripts, automation tools and
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frameworks. Usage by non-engineers and ordinary users is unusual.
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""",
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]
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from = "now-9m"
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index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*", "logs-system.*"]
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language = "eql"
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license = "Elastic License v2"
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name = "Whoami Process Activity"
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note = """## Triage and analysis
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### Investigating Whoami Process Activity
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After successfully compromising an environment, attackers may try to gain situational awareness to plan their next steps.
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This can happen by running commands to enumerate network resources, users, connections, files, and installed security
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software.
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This rule looks for the execution of the `whoami` utility. Attackers commonly use this utility to measure their current
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privileges, discover the current user, determine if a privilege escalation was successful, etc.
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#### Possible investigation steps
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- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
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for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
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- Identify the user account that performed the action and whether it should perform this kind of action.
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- Investigate other alerts associated with the user/host during the past 48 hours.
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- Investigate abnormal behaviors observed using the account, such as commands executed, files created or modified, and
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network connections.
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### False positive analysis
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- Discovery activities are not inherently malicious if they occur in isolation. As long as the analyst did not identify
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suspicious activity related to the user or host, such alerts can be dismissed.
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### Related rules
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- Account Discovery Command via SYSTEM Account - 2856446a-34e6-435b-9fb5-f8f040bfa7ed
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### Response and remediation
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- Initiate the incident response process based on the outcome of the triage.
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- Isolate the involved hosts to prevent further post-compromise behavior.
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- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
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identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
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systems, and web services.
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- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
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malware components.
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- Determine the initial vector abused by the attacker and take action to prevent reinfection via the same vector.
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- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
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mean time to respond (MTTR).
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## Setup
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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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"""
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risk_score = 21
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rule_id = "ef862985-3f13-4262-a686-5f357bbb9bc2"
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severity = "low"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Discovery"]
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timestamp_override = "event.ingested"
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type = "eql"
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query = '''
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process where event.type in ("start", "process_started") and process.name : "whoami.exe" and
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(
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(/* scoped for whoami execution under system privileges */
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(user.domain : ("NT AUTHORITY", "NT-AUTORITÄT", "AUTORITE NT", "IIS APPPOOL") or user.id : ("S-1-5-18", "S-1-5-19", "S-1-5-20")) and
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not (process.parent.name : "cmd.exe" and
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process.parent.args : ("chcp 437>nul 2>&1 & C:\\WINDOWS\\System32\\whoami.exe /groups",
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"chcp 437>nul 2>&1 & %systemroot%\\system32\\whoami /user",
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"C:\\WINDOWS\\System32\\whoami.exe /groups",
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"*WINDOWS\\system32\\config\\systemprofile*")) and
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not (process.parent.executable : "C:\\Windows\\system32\\inetsrv\\appcmd.exe" and process.parent.args : "LIST") and
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not process.parent.executable : ("C:\\Program Files\\Microsoft Monitoring Agent\\Agent\\MonitoringHost.exe",
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"C:\\Program Files\\Cohesity\\cohesity_windows_agent_service.exe")) or
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process.parent.name : ("wsmprovhost.exe", "w3wp.exe", "wmiprvse.exe", "rundll32.exe", "regsvr32.exe")
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)
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'''
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[[rule.threat]]
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framework = "MITRE ATT&CK"
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[[rule.threat.technique]]
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id = "T1033"
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name = "System Owner/User Discovery"
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reference = "https://attack.mitre.org/techniques/T1033/"
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[rule.threat.tactic]
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id = "TA0007"
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name = "Discovery"
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reference = "https://attack.mitre.org/tactics/TA0007/"
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