Jonhnathan
f02ffbbe13
* [Security Content] Add Investigation Guides - 8.5 * Update persistence_run_key_and_startup_broad.toml * Apply suggestions from security-docs review review * Update execution_suspicious_jar_child_process.toml * Apply suggestions from review
111 lines
5.0 KiB
TOML
111 lines
5.0 KiB
TOML
[metadata]
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creation_date = "2020/02/18"
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maturity = "production"
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min_stack_comments = "New fields added: required_fields, related_integrations, setup"
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min_stack_version = "8.3.0"
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updated_date = "2022/09/20"
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[rule]
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author = ["Elastic"]
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description = """
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Identifies a PowerShell process launched by either cscript.exe or wscript.exe. Observing Windows scripting processes
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executing a PowerShell script, may be indicative of malicious activity.
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"""
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from = "now-9m"
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index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*"]
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language = "eql"
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license = "Elastic License v2"
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name = "Windows Script Executing PowerShell"
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note = """## Triage and analysis
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### Investigating Windows Script Executing PowerShell
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The Windows Script Host (WSH) is an Windows automation technology, which is ideal for non-interactive scripting needs,
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such as logon scripting, administrative scripting, and machine automation.
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Attackers commonly use WSH scripts as their initial access method, acting like droppers for second stage payloads, but
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can also use them to download tools and utilities needed to accomplish their goals.
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This rule looks for the spawn of the `powershell.exe` process with `cscript.exe` or `wscript.exe` as its parent process.
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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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- Investigate commands executed by the spawned PowerShell process.
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- If unsigned files are found on the process tree, retrieve them and determine if they are malicious:
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- Use a private sandboxed malware analysis system to perform analysis.
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- Observe and collect information about the following activities:
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- Attempts to contact external domains and addresses.
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- File and registry access, modification, and creation activities.
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- Service creation and launch activities.
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- Scheduled task creation.
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- Use the PowerShell Get-FileHash cmdlet to get the files' SHA-256 hash values.
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- Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
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- Determine how the script file was delivered (email attachment, dropped by other processes, etc.).
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- Investigate other alerts associated with the user/host during the past 48 hours.
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### False positive analysis
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- The usage of these script engines by regular users is unlikely. In the case of authorized benign true positives
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(B-TPs), exceptions can be added.
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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 host to prevent further post-compromise behavior.
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- If the triage identified malware, search the environment for additional compromised hosts.
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- Implement temporary network rules, procedures, and segmentation to contain the malware.
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- Stop suspicious processes.
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- Immediately block the identified indicators of compromise (IoCs).
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- Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that
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attackers could use to reinfect the system.
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- Remove and block malicious artifacts identified during triage.
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- If the malicious file was delivered via phishing:
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- Block the email sender from sending future emails.
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- Block the malicious web pages.
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- Remove emails from the sender from mailboxes.
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- Consider improvements to the security awareness program.
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- Reimage the host operating system and restore compromised files to clean versions.
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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 through 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 = "f545ff26-3c94-4fd0-bd33-3c7f95a3a0fc"
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severity = "low"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Initial Access", "has_guide"]
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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 == "start" and
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process.parent.name : ("cscript.exe", "wscript.exe") and process.name : "powershell.exe"
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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 = "T1566"
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name = "Phishing"
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reference = "https://attack.mitre.org/techniques/T1566/"
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[[rule.threat.technique.subtechnique]]
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id = "T1566.001"
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name = "Spearphishing Attachment"
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reference = "https://attack.mitre.org/techniques/T1566/001/"
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[rule.threat.tactic]
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id = "TA0001"
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name = "Initial Access"
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reference = "https://attack.mitre.org/tactics/TA0001/"
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