[Detection Rules] Adding Documents for v8.10.3 Pre-Built Detection Rules

docs/detections/prebuilt-rules/downloadable-packages/8-10-3/prebuilt-rule-8-10-3-github-protected-branch-settings-changed.asciidoc

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+[[prebuilt-rule-8-10-3-github-protected-branch-settings-changed]]
+=== GitHub Protected Branch Settings Changed
+
+This rule detects setting modifications for protected branches of a GitHub repository. Branch protection rules can be used to enforce certain workflows or requirements before a contributor can push changes to a branch in your repository. Changes to these protected branch settings should be investigated and verified as legitimate activity. Unauthorized changes could be used to lower your organization's security posture and leave you exposed for future attacks.
+
+*Rule type*: eql
+
+*Rule indices*: 
+
+* logs-github.audit-*
+
+*Severity*: medium
+
+*Risk score*: 47
+
+*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: Cloud
+* Use Case: Threat Detection
+* Tactic: Defense Evasion
+* Data Source: Github
+
+*Version*: 1
+
+*Rule authors*: 
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Rule query
+
+
+[source, js]
+----------------------------------
+configuration where event.dataset == "github.audit" 
+  and github.category == "protected_branch" and event.type == "change" 
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Defense Evasion
+** ID: TA0005
+** Reference URL: https://attack.mitre.org/tactics/TA0005/
+* Technique:
+** Name: Impair Defenses
+** ID: T1562
+** Reference URL: https://attack.mitre.org/techniques/T1562/
+* Sub-technique:
+** Name: Disable or Modify Tools
+** ID: T1562.001
+** Reference URL: https://attack.mitre.org/techniques/T1562/001/

docs/detections/prebuilt-rules/downloadable-packages/8-10-3/prebuilt-rule-8-10-3-github-repository-deleted.asciidoc

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+[[prebuilt-rule-8-10-3-github-repository-deleted]]
+=== GitHub Repository Deleted
+
+This rule detects when a GitHub repository is deleted within your organization. Repositories are a critical component used within an organization to manage work, collaborate with others and release products to the public. Any delete action against a repository should be investigated to determine it's validity. Unauthorized deletion of organization repositories could cause irreversible loss of intellectual property and indicate compromise within your organization.
+
+*Rule type*: eql
+
+*Rule indices*: 
+
+* logs-github.audit-*
+
+*Severity*: medium
+
+*Risk score*: 47
+
+*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: Cloud
+* Use Case: Threat Detection
+* Tactic: Impact
+* Data Source: Github
+
+*Version*: 1
+
+*Rule authors*: 
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Rule query
+
+
+[source, js]
+----------------------------------
+configuration where event.module == "github" and event.action == "repo.destroy"
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Impact
+** ID: TA0040
+** Reference URL: https://attack.mitre.org/tactics/TA0040/
+* Technique:
+** Name: Data Destruction
+** ID: T1485
+** Reference URL: https://attack.mitre.org/techniques/T1485/

docs/detections/prebuilt-rules/downloadable-packages/8-10-3/prebuilt-rule-8-10-3-network-activity-detected-via-cat.asciidoc

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+[[prebuilt-rule-8-10-3-network-activity-detected-via-cat]]
+=== Network Activity Detected via cat
+
+This rule monitors for the execution of the cat command, followed by a connection attempt by the same process. Cat is capable of transfering data via tcp/udp channels by redirecting its read output to a /dev/tcp or /dev/udp channel. This activity is highly suspicious, and should be investigated. Attackers may leverage this capability to transfer tools or files to another host in the network or exfiltrate data while attempting to evade detection in the process.
+
+*Rule type*: eql
+
+*Rule indices*: 
+
+* logs-endpoint.events.*
+
+*Severity*: medium
+
+*Risk score*: 47
+
+*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: Linux
+* Use Case: Threat Detection
+* Tactic: Command and Control
+* Data Source: Elastic Defend
+
+*Version*: 1
+
+*Rule authors*: 
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Rule query
+
+
+[source, js]
+----------------------------------
+sequence by host.id, process.entity_id with maxspan=1s
+  [process where host.os.type == "linux" and event.action == "exec" and event.type == "start" and 
+   process.name == "cat"]
+  [network where host.os.type == "linux" and event.action in ("connection_attempted", "disconnect_received") and 
+   process.name == "cat"]
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Command and Control
+** ID: TA0011
+** Reference URL: https://attack.mitre.org/tactics/TA0011/
+* Tactic:
+** Name: Defense Evasion
+** ID: TA0005
+** Reference URL: https://attack.mitre.org/tactics/TA0005/
+* Tactic:
+** Name: Exfiltration
+** ID: TA0010
+** Reference URL: https://attack.mitre.org/tactics/TA0010/

docs/detections/prebuilt-rules/downloadable-packages/8-10-3/prebuilt-rule-8-10-3-persistent-scripts-in-the-startup-directory.asciidoc

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+[[prebuilt-rule-8-10-3-persistent-scripts-in-the-startup-directory]]
+=== Persistent Scripts in the Startup Directory
+
+Identifies script engines creating files in the Startup folder, or the creation of script files in the Startup folder. Adversaries may abuse this technique to maintain persistence in an environment.
+
+*Rule type*: eql
+
+*Rule indices*:
+
+* winlogbeat-*
+* logs-endpoint.events.*
+* logs-windows.*
+* endgame-*
+
+*Severity*: medium
+
+*Risk score*: 47
+
+*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: Persistence
+* Resources: Investigation Guide
+* Data Source: Elastic Endgame
+* Data Source: Elastic Defend
+
+*Version*: 108
+
+*Rule authors*:
+
+* Elastic
+
+*Rule license*: Elastic License v2
+
+
+==== Investigation guide
+
+
+[source, markdown]
+----------------------------------
+## Triage and analysis
+
+### Investigating Persistent Scripts in the Startup Directory
+
+The Windows Startup folder is a special folder in Windows. Programs added to this folder are executed during account logon, without user interaction, providing an excellent way for attackers to maintain persistence.
+
+This rule looks for shortcuts created by wscript.exe or cscript.exe, or js/vbs scripts created by any process.
+
+> **Note**:
+> This investigation guide uses the {security-guide}/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
+
+- 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.
+- Validate if the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations.
+- Assess whether this behavior is prevalent in the environment by looking for similar occurrences across hosts.
+- Examine the host for derived artifacts that indicate suspicious activities:
+  - Analyze the file using a private sandboxed analysis system.
+  - Observe and collect information about the following activities in both the sandbox and 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"}}
+  - 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.
+- Investigate potentially compromised accounts. Analysts can do this by searching for login events (for example, 4624) to the target host after the registry modification.
+
+### False positive analysis
+
+- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
+
+### Related rules
+
+- Suspicious Startup Shell Folder Modification - c8b150f0-0164-475b-a75e-74b47800a9ff
+- Startup Folder Persistence via Unsigned Process - 2fba96c0-ade5-4bce-b92f-a5df2509da3f
+
+### 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.
+- 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.
+- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
+- 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]
+----------------------------------
+file where host.os.type == "windows" and event.type != "deletion" and user.domain != "NT AUTHORITY" and
+
+  /* detect shortcuts created by wscript.exe or cscript.exe */
+  (file.path : "C:\\*\\Programs\\Startup\\*.lnk" and
+     process.name : ("wscript.exe", "cscript.exe")) or
+
+  /* detect vbs or js files created by any process */
+  file.path : ("C:\\*\\Programs\\Startup\\*.vbs",
+               "C:\\*\\Programs\\Startup\\*.vbe",
+               "C:\\*\\Programs\\Startup\\*.wsh",
+               "C:\\*\\Programs\\Startup\\*.wsf",
+               "C:\\*\\Programs\\Startup\\*.js")
+
+----------------------------------
+
+*Framework*: MITRE ATT&CK^TM^
+
+* Tactic:
+** Name: Persistence
+** ID: TA0003
+** Reference URL: https://attack.mitre.org/tactics/TA0003/
+* Technique:
+** Name: Boot or Logon Autostart Execution
+** ID: T1547
+** Reference URL: https://attack.mitre.org/techniques/T1547/
+* Sub-technique:
+** Name: Registry Run Keys / Startup Folder
+** ID: T1547.001
+** Reference URL: https://attack.mitre.org/techniques/T1547/001/
+* Sub-technique:
+** Name: Shortcut Modification
+** ID: T1547.009
+** Reference URL: https://attack.mitre.org/techniques/T1547/009/