[Detection Rules] Adding Documents for v8.19.1 Pre-Built Detection Rules

docs/detections/prebuilt-rules/downloadable-packages/8-19-1/prebuilt-rule-8-19-1-adding-hidden-file-attribute-via-attrib.asciidoc

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+[[prebuilt-rule-8-19-1-adding-hidden-file-attribute-via-attrib]]
+=== Adding Hidden File Attribute via Attrib
+
+Adversaries can add the 'hidden' attribute to files to hide them from the user in an attempt to evade detection.
+
+*Rule type*: eql
+
+*Rule indices*: 
+
+* endgame-*
+* logs-crowdstrike.fdr*
+* logs-endpoint.events.process-*
+* logs-m365_defender.event-*
+* logs-sentinel_one_cloud_funnel.*
+* logs-system.security*
+* logs-windows.forwarded*
+* logs-windows.sysmon_operational-*
+* winlogbeat-*
+
+*Severity*: low
+
+*Risk score*: 21
+
+*Runs every*: 5m
+
+*Searches indices from*: now-9m ({ref}/common-options.html#date-math[Date Math format], see also <<rule-schedule, `Additional look-back time`>>)
+
+*Maximum alerts per execution*: 100
+
+*References*: None
+
+*Tags*: 
+
+* Domain: Endpoint
+* OS: Windows
+* Use Case: Threat Detection
+* Tactic: Defense Evasion
+* Tactic: Persistence
+* Data Source: Elastic Endgame
+* Resources: Investigation Guide
+* Data Source: Elastic Defend
+* Data Source: Windows Security Event Logs
+* Data Source: Microsoft Defender for Endpoint
+* Data Source: Sysmon
+* Data Source: SentinelOne
+* Data Source: Crowdstrike
+
+*Version*: 319
+
+*Rule authors*: 
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Investigation guide
+
+
+
+*Triage and analysis*
+
+
+
+*Investigating Adding Hidden File Attribute via Attrib*
+
+
+The `Hidden` attribute is a file or folder attribute that makes the file or folder invisible to regular directory listings when the attribute is set. 
+
+Attackers can use this attribute to conceal tooling and malware to prevent administrators and users from finding it, even if they are looking specifically for it.
+
+This rule looks for the execution of the `attrib.exe` utility with a command line that indicates the modification of the `Hidden` attribute.
+
+> **Note**:
+> This investigation guide uses the https://www.elastic.co/guide/en/security/current/invest-guide-run-osquery.html[Osquery Markdown Plugin] introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
+
+
+*Possible investigation steps*
+
+
+- Identify the user account that performed the action and whether it should perform this kind of action.
+- Contact the account owner and confirm whether they are aware of this activity.
+- 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.
+- Examine the command line to identify the target file or folder.
+  - Examine the file, which process created it, header, etc.
+  - If suspicious, retrieve the files' SHA-256 hash values using the PowerShell `Get-FileHash` cmdlet and search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
+- Examine the host for derived artifacts that indicate suspicious activities:
+  - Observe and collect information about the following activities in the alert subject host:
+    - Attempts to contact external domains and addresses.
+      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process' `process.entity_id`.
+      - Examine the DNS cache for suspicious or anomalous entries.
+        - !{osquery{"label":"Osquery - Retrieve DNS Cache","query":"SELECT * FROM dns_cache"}}
+    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
+    - Examine the host services for suspicious or anomalous entries.
+      - !{osquery{"label":"Osquery - Retrieve All Services","query":"SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services"}}
+      - !{osquery{"label":"Osquery - Retrieve Services Running on User Accounts","query":"SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services WHERE\nNOT (user_account LIKE '%LocalSystem' OR user_account LIKE '%LocalService' OR user_account LIKE '%NetworkService' OR\nuser_account == null)\n"}}
+      - !{osquery{"label":"Osquery - Retrieve Service Unsigned Executables with Virustotal Link","query":"SELECT concat('https://www.virustotal.com/gui/file/', sha1) AS VtLink, name, description, start_type, status, pid,\nservices.path FROM services JOIN authenticode ON services.path = authenticode.path OR services.module_path =\nauthenticode.path JOIN hash ON services.path = hash.path WHERE authenticode.result != 'trusted'\n"}}
+
+
+*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.
+- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business systems, and web services.
+- 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
+
+
+[source, js]
+----------------------------------
+process where host.os.type == "windows" and event.type == "start" and
+  (process.name : "attrib.exe" or ?process.pe.original_file_name == "ATTRIB.EXE") and process.args : "+h" and
+  not (process.parent.name: "cmd.exe" and process.command_line: "attrib  +R +H +S +A *.cui") and
+
+  not (
+    process.parent.name: "draw.io.exe" and
+    (
+      process.command_line : ("*drawio.bkp*", "*drawio.dtmp*")
+    )
+  )
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Defense Evasion
+** ID: TA0005
+** Reference URL: https://attack.mitre.org/tactics/TA0005/
+* Technique:
+** Name: File and Directory Permissions Modification
+** ID: T1222
+** Reference URL: https://attack.mitre.org/techniques/T1222/
+* Sub-technique:
+** Name: Windows File and Directory Permissions Modification
+** ID: T1222.001
+** Reference URL: https://attack.mitre.org/techniques/T1222/001/
+* Technique:
+** Name: Hide Artifacts
+** ID: T1564
+** Reference URL: https://attack.mitre.org/techniques/T1564/
+* Sub-technique:
+** Name: Hidden Files and Directories
+** ID: T1564.001
+** Reference URL: https://attack.mitre.org/techniques/T1564/001/
+* Tactic:
+** Name: Persistence
+** ID: TA0003
+** Reference URL: https://attack.mitre.org/tactics/TA0003/

docs/detections/prebuilt-rules/downloadable-packages/8-19-1/prebuilt-rule-8-19-1-aws-ssm-command-document-created-by-rare-user.asciidoc

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+[[prebuilt-rule-8-19-1-aws-ssm-command-document-created-by-rare-user]]
+=== AWS SSM Command Document Created by Rare User
+
+Identifies when an AWS Systems Manager (SSM) command document is created by a user or role who does not typically perform this action. Adversaries may create SSM command documents to execute commands on managed instances, potentially leading to unauthorized access, command and control, data exfiltration and more.
+
+*Rule type*: new_terms
+
+*Rule indices*: 
+
+* filebeat-*
+* logs-aws.cloudtrail-*
+
+*Severity*: low
+
+*Risk score*: 21
+
+*Runs every*: 5m
+
+*Searches indices from*: now-6m ({ref}/common-options.html#date-math[Date Math format], see also <<rule-schedule, `Additional look-back time`>>)
+
+*Maximum alerts per execution*: 100
+
+*References*: 
+
+* https://docs.aws.amazon.com/systems-manager/latest/APIReference/API_CreateDocument.html
+* https://docs.aws.amazon.com/systems-manager/latest/userguide/documents.html
+
+*Tags*: 
+
+* Domain: Cloud
+* Data Source: AWS
+* Data Source: Amazon Web Services
+* Data Source: AWS SSM
+* Data Source: AWS Systems Manager
+* Resources: Investigation Guide
+* Use Case: Threat Detection
+* Tactic: Execution
+
+*Version*: 5
+
+*Rule authors*: 
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Investigation guide
+
+
+
+*Triage and analysis*
+
+
+
+*Investigating AWS SSM Command Document Created by Rare User*
+
+
+This rule identifies when an AWS Systems Manager (SSM) command document is created by a user who does not typically perform this action. Creating SSM command documents can be a legitimate action but may also indicate malicious intent if done by an unusual or compromised user. Adversaries may leverage SSM documents to execute commands on managed instances, potentially leading to unauthorized access, command and control, or data exfiltration.
+
+
+*Possible Investigation Steps*
+
+
+- **Identify the Actor**: Review the `aws.cloudtrail.user_identity.arn` field to identify who created the SSM document. Verify if this user typically creates such documents and has the appropriate permissions. It may be unexpected for certain types of users, like assumed roles or federated users, to perform this action.
+- **Analyze the Document Details**:
+  - **Document Name**: Check the `aws.cloudtrail.request_parameters.name` field for the document name to understand its intended purpose.
+  - **Document Content**: If possible, review `aws.cloudtrail.request_parameters.content` for any sensitive or unexpected instructions (e.g., actions for data exfiltration or privilege escalation). If not available via logs, consider reviewing the document in the AWS Management Console.
+- **Contextualize the Activity with Related Events**: Look for other CloudTrail events involving the same user ARN or IP address (`source.ip`). Examine actions performed in other AWS services, such as IAM, EC2, or S3, to identify if additional suspicious behavior exists. The `SendCommand` API call may indicate attempts to execute the SSM document on managed instances.
+- **Check Document Status and Metadata**:
+  - **Document Status**: Confirm the document creation status in `aws.cloudtrail.response_elements.documentDescription.status`. A status of `Creating` may indicate that the document is in progress.
+  - **Execution Permissions**: Review if the document specifies `platformTypes` and `documentVersion` in `aws.cloudtrail.response_elements.documentDescription` to understand which environments may be impacted and if multiple versions exist.
+
+
+*False Positive Analysis*
+
+
+- **Authorized Administrative Actions**: Determine if this document creation aligns with scheduled administrative tasks or actions by authorized personnel.
+- **Historical User Actions**: Compare this action against historical activities for the user to determine if they have a history of creating similar documents, which may indicate legitimate usage.
+
+
+*Response and Remediation*
+
+
+- **Immediate Document Review and Deletion**: If the document creation is deemed unauthorized, delete the document immediately and check for other similar documents created recently.
+- **Enhance Monitoring and Alerts**: Configure additional monitoring for SSM document creation events, especially when associated with untrusted or rare users.
+- **Policy Update**: Consider restricting SSM document creation permissions to specific, trusted roles or users to prevent unauthorized document creation.
+- **Incident Response**: If the document is confirmed as part of malicious activity, treat this as a security incident. Follow incident response protocols, including containment, investigation, and remediation.
+
+
+*Additional Information*
+
+
+For further guidance on managing and securing AWS Systems Manager in your environment, refer to the https://docs.aws.amazon.com/systems-manager/latest/userguide/what-is-systems-manager.html[AWS SSM documentation] and AWS security best practices.
+
+
+==== Rule query
+
+
+[source, js]
+----------------------------------
+event.dataset: "aws.cloudtrail"
+    and event.provider: "ssm.amazonaws.com"
+    and event.action: "CreateDocument"
+    and event.outcome: "success"
+    and aws.cloudtrail.flattened.response_elements.documentDescription.documentType: "Command"
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Execution
+** ID: TA0002
+** Reference URL: https://attack.mitre.org/tactics/TA0002/
+* Technique:
+** Name: Cloud Administration Command
+** ID: T1651
+** Reference URL: https://attack.mitre.org/techniques/T1651/