Jonhnathan
7fdf870d31
* [Security Content] Add Investigation Guides - 3
* Adjust Investigation Guides and Config
* Adjust Config
Co-authored-by: Colson Wilhoit <48036388+DefSecSentinel@users.noreply.github.com>
Co-authored-by: Mika Ayenson <Mikaayenson@users.noreply.github.com>
Co-authored-by: Terrance DeJesus <99630311+terrancedejesus@users.noreply.github.com>
Co-authored-by: benironside <91905639+benironside@users.noreply.github.com>
(cherry picked from commit 3a5fceac3b)
114 lines
4.3 KiB
TOML
114 lines
4.3 KiB
TOML
[metadata]
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creation_date = "2022/01/31"
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maturity = "production"
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updated_date = "2022/03/31"
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[rule]
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author = ["Elastic"]
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description = """
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Identifies attempts to disable PowerShell Script Block Logging via registry modification. Attackers may disable this
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logging to conceal their activities in the host and evade detection.
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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 = "PowerShell Script Block Logging Disabled"
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note = """## Triage and analysis
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### Investigating PowerShell Script Block Logging Disabled
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PowerShell is one of the main tools system administrators use for automation, report routines, and other tasks, making
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it available in various environments and creating an attractive way for attackers to execute code.
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PowerShell Script Block Logging is a feature of PowerShell that records the content of all script blocks that it
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processes, giving defenders visibility of PowerShell scripts and sequences of executed commands.
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#### Possible investigation steps
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- Identify the user account which performed the action.
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- Check whether the account should perform this kind of action.
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- Investigate the script execution chain (parent process tree).
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- Investigate other alerts related to the user/host in the last 48 hours.
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- Check whether it makes sense for the user to use PowerShell to complete its tasks.
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- Investigate if PowerShell scripts were run after logging was disabled.
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### False positive analysis
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- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
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### Related rules
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- PowerShell Suspicious Discovery Related Windows API Functions - 61ac3638-40a3-44b2-855a-985636ca985e
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- PowerShell Keylogging Script - bd2c86a0-8b61-4457-ab38-96943984e889
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- PowerShell Suspicious Script with Audio Capture Capabilities - 2f2f4939-0b34-40c2-a0a3-844eb7889f43
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- Potential Process Injection via PowerShell - 2e29e96a-b67c-455a-afe4-de6183431d0d
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- PowerShell Reflection Assembly Load - e26f042e-c590-4e82-8e05-41e81bd822ad
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- PowerShell Suspicious Payload Encoded and Compressed - 81fe9dc6-a2d7-4192-a2d8-eed98afc766a
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- PowerShell Suspicious Script with Screenshot Capabilities - 959a7353-1129-4aa7-9084-30746b256a70
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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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- Quarantine the involved host to prevent further post-compromise behavior.
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- Review the implicated user account's privileges.
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- Configure AppLocker or equivalent software to restrict access to PowerShell for regular users.
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## Config
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The 'PowerShell Script Block Logging' logging policy must be configured (Enable).
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Steps to implement the logging policy with with Advanced Audit Configuration:
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```
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Computer Configuration >
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Administrative Templates >
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Windows PowerShell >
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Turn on PowerShell Script Block Logging (Enable)
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```
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Steps to implement the logging policy via registry:
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```
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reg add "hklm\\SOFTWARE\\Policies\\Microsoft\\Windows\\PowerShell\\ScriptBlockLogging" /v EnableScriptBlockLogging /t REG_DWORD /d 1
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```
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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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references = [
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"https://admx.help/?Category=Windows_10_2016&Policy=Microsoft.Policies.PowerShell::EnableScriptBlockLogging",
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]
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risk_score = 47
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rule_id = "818e23e6-2094-4f0e-8c01-22d30f3506c6"
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severity = "medium"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Defense Evasion"]
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timestamp_override = "event.ingested"
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type = "eql"
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query = '''
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registry where event.type == "change" and
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registry.path :
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"HKLM\\SOFTWARE\\Policies\\Microsoft\\Windows\\PowerShell\\ScriptBlockLogging\\EnableScriptBlockLogging"
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and registry.data.strings : ("0", "0x00000000")
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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 = "T1562"
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name = "Impair Defenses"
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reference = "https://attack.mitre.org/techniques/T1562/"
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[[rule.threat.technique.subtechnique]]
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id = "T1562.002"
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name = "Disable Windows Event Logging"
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reference = "https://attack.mitre.org/techniques/T1562/002/"
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[rule.threat.tactic]
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id = "TA0005"
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name = "Defense Evasion"
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reference = "https://attack.mitre.org/tactics/TA0005/"
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