protectionsmachine
commented
2 months ago Rule: Tuning - Guidelines
These guidelines serve as a reminder set of considerations when tuning an existing rule.
Documentation and Context
- [ ] Detailed description of the suggested changes.
- [ ] Provide example JSON data or screenshots.
- [ ] Provide evidence of reducing benign events mistakenly identified as threats (False Positives).
- [ ] Provide evidence of enhancing detection of true threats that were previously missed (False Negatives).
- [ ] Provide evidence of optimizing resource consumption and execution time of detection rules (Performance).
- [ ] Provide evidence of specific environment factors influencing customized rule tuning (Contextual Tuning).
- [ ] Provide evidence of improvements made by modifying sensitivity by changing alert triggering thresholds (Threshold Adjustments).
- [ ] Provide evidence of refining rules to better detect deviations from typical behavior (Behavioral Tuning).
- [ ] Provide evidence of improvements of adjusting rules based on time-based patterns (Temporal Tuning).
- [ ] Provide reasoning of adjusting priority or severity levels of alerts (Severity Tuning).
- [ ] Provide evidence of improving quality integrity of our data used by detection rules (Data Quality).
- [ ] Ensure the tuning includes necessary updates to the release documentation and versioning.
Rule Metadata Checks
- [ ]
updated_datematches the date of tuning PR merged. - [ ]
min_stack_versionshould support the widest stack versions. - [ ]
nameanddescriptionshould be descriptive and not include typos. - [ ]
queryshould be inclusive, not overly exclusive. Review to ensure the original intent of the rule is maintained.
Testing and Validation
- [ ] Validate that the tuned rule's performance is satisfactory and does not negatively impact the stack.
- [ ] Ensure that the tuned rule has a low false positive rate.
Issues
Resolves #3807
Summary
Changes the args we look for in this rule to match the syntax that actually works and removed the
passwordkeyword as it is not needed to obtain passwords. I've moved this one to BBR so we can validate the noise of this change and tune it before reintroducing it as a normal DR, as we don't have any TP telemetry.Data
Sample Event
``` { "_index": ".ds-logs-endpoint.events.process-default-2024.07.12-000026", "_id": "Mgl6CZEBiLqpmBCYtAJu", "_score": 1, "_source": { "agent": { "id": "c725ae87-e846-4602-9a08-2c717a3a504b", "type": "endpoint", "version": "8.14.2" }, "process": { "Ext": { "mitigation_policies": [ "CF Guard" ], "ancestry": [ "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTEwMTkyLTE3MjI0NDA2ODMuMzEzOTUwOTAw", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTYyMjQtMTcyMjI5MzE4MS4zNTUwODc0MDA=", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTgxMi0xNzIyMjkzMTgxLjI3NzgwOTcwMA==", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTY3Mi0xNzIyMjUwMzY4LjEyOTg3MTAwMA==" ], "code_signature": [ { "trusted": true, "subject_name": "Microsoft Windows", "exists": true, "status": "trusted" } ], "session_info": { "authentication_package": "Kerberos", "relative_password_age": 1815857.0507085, "user_flags": [ "LOGON_EXTRA_SIDS", "LOGON_WINLOGON" ], "relative_logon_time": 147713.5745794, "id": 1, "logon_type": "Interactive" }, "relative_file_creation_time": 185444653.4212362, "authentication_id": "0x2e8b75f", "relative_file_name_modify_time": 101645988.4863966, "token": { "integrity_level_name": "high", "security_attributes": [ "TSA://ProcUnique" ], "elevation_level": "full" } }, "parent": { "Ext": { "code_signature": [ { "trusted": true, "subject_name": "Microsoft Windows", "exists": true, "status": "trusted" } ] }, "args": [ "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" ], "code_signature": { "trusted": true, "subject_name": "Microsoft Windows", "exists": true, "status": "trusted" }, "name": "powershell.exe", "pid": 10192, "args_count": 1, "thread": { "Ext": { "call_stack_summary": "ntdll.dll|kernelbase.dll|kernel32.dll|system.ni.dll|system.management.automation.ni.dll|Unbacked", "call_stack_contains_unbacked": true, "call_stack": [ { "symbol_info": "C:\\Windows\\System32\\ntdll.dll!ZwCreateUserProcess+0x14" }, { "symbol_info": "C:\\Windows\\System32\\KernelBase.dll!CreateProcessInternalW+0x1f12" }, { "symbol_info": "C:\\Windows\\System32\\KernelBase.dll!CreateProcessW+0x66" }, { "symbol_info": "C:\\Windows\\System32\\kernel32.dll!CreateProcessW+0x53" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x334376" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x2b65a0" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x2b5f47" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf7fc5b" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xed9f9d" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf5cb0e" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf5c7eb" }, { "symbol_info": "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0x104fca4" }, { "symbol_info": "Unbacked+0x3211", "callsite_trailing_bytes": "834648fab8010000004883c4685b5d5e5f415c415d415e415fc3e8c02a945fcc0000001910090010c20c300b500a60097008c006d004e002f000004000000000", "protection": "RWX", "callsite_leading_bytes": "2428f6c1017404488b49ffe8af9b5d5f4889442430498bd5448b44245c4c8b4c2448488b6c244048896c2420488b6c243848896c2428488d4b08488b09ff5318" } ] } }, "entity_id": "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTEwMTkyLTE3MjI0NDA2ODMuMzEzOTUwOTAw", "command_line": "\"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe\" ", "executable": "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" }, "pid": 5708, "working_directory": "C:\\Windows\\System32\\inetsrv\\", "entity_id": "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTU3MDgtMTcyMjQ0MDg5Mi40MzU1Mzc0MDA=", "executable": "C:\\Windows\\System32\\inetsrv\\appcmd.exe", "args": [ "C:\\Windows\\System32\\inetsrv\\appcmd.exe", "list", "apppool", "WsusPool", "/text:*" ], "code_signature": { "trusted": true, "subject_name": "Microsoft Windows", "exists": true, "status": "trusted" }, "pe": { "imphash": "0c59ba75971a266506603cef51da9ceb", "original_file_name": "appcmd.exe" }, "name": "appcmd.exe", "args_count": 5, "command_line": "\"C:\\Windows\\System32\\inetsrv\\appcmd.exe\" list apppool WsusPool /text:*", "hash": { "sha1": "fcd71b4916276d196f460b0a976efbb8adf3ec63", "sha256": "429bc84babe1387abf59eefb0b225a1f5317fdb1d3f29995dbd5604e78b3ac33", "md5": "698a7b8dcf5b3f2f0cc15b2a6b18e360" } }, "@timestamp": "2024-07-31T15:48:12.4355374Z", "ecs": { "version": "8.10.0" }, "data_stream": { "namespace": "default", "type": "logs", "dataset": "endpoint.events.process" }, "elastic": { "agent": { "id": "c725ae87-e846-4602-9a08-2c717a3a504b" } }, "host": { "hostname": "kingslanding", "os": { "Ext": { "variant": "Windows Server 2019 Datacenter Evaluation" }, "kernel": "1809 (10.0.17763.1935)", "name": "Windows", "family": "windows", "type": "windows", "version": "1809 (10.0.17763.1935)", "platform": "windows", "full": "Windows Server 2019 Datacenter Evaluation 1809 (10.0.17763.1935)" }, "domain": "sevenkingdoms.local", "ip": [ "192.168.56.10", "192.168.133.195", "127.0.0.1", "::1" ], "name": "kingslanding", "id": "bb11c0d0-189a-4fad-aa85-e71a5b6c7ed9", "mac": [ "00-0c-29-f8-cf-09", "00-0c-29-f8-cf-ff" ], "architecture": "x86_64" }, "event": { "agent_id_status": "verified", "sequence": 1478750, "ingested": "2024-07-31T15:48:42Z", "created": "2024-07-31T15:48:12.4355374Z", "kind": "event", "module": "endpoint", "action": "start", "id": "NeRojTexa6/KxECF++++lFIa", "category": [ "process" ], "type": [ "start" ], "dataset": "endpoint.events.process", "outcome": "unknown" }, "message": "Endpoint process event", "user": { "domain": "SEVENKINGDOMS", "name": "robert.baratheon", "id": "S-1-5-21-3715621034-4113696668-281506975-1117" } }, "fields": { "process.hash.md5": [ "698a7b8dcf5b3f2f0cc15b2a6b18e360" ], "host.os.full.text": [ "Windows Server 2019 Datacenter Evaluation 1809 (10.0.17763.1935)" ], "process.command_line.caseless": [ "\"c:\\windows\\system32\\inetsrv\\appcmd.exe\" list apppool wsuspool /text:*" ], "event.category": [ "process" ], "host.os.name.text": [ "Windows" ], "process.parent.command_line": [ "\"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe\" " ], "process.parent.name": [ "powershell.exe" ], "process.hash.sha256": [ "429bc84babe1387abf59eefb0b225a1f5317fdb1d3f29995dbd5604e78b3ac33" ], "process.parent.pid": [ 10192 ], "host.hostname": [ "kingslanding" ], "host.mac": [ "00-0c-29-f8-cf-09", "00-0c-29-f8-cf-ff" ], "process.code_signature.exists": [ true ], "elastic.agent.id": [ "c725ae87-e846-4602-9a08-2c717a3a504b" ], "host.domain": [ "sevenkingdoms.local" ], "host.os.version": [ "1809 (10.0.17763.1935)" ], "event.agent_id_status": [ "verified" ], "event.outcome": [ "unknown" ], "host.os.type": [ "windows" ], "user.id": [ "S-1-5-21-3715621034-4113696668-281506975-1117" ], "process.Ext.ancestry": [ "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTEwMTkyLTE3MjI0NDA2ODMuMzEzOTUwOTAw", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTYyMjQtMTcyMjI5MzE4MS4zNTUwODc0MDA=", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTgxMi0xNzIyMjkzMTgxLjI3NzgwOTcwMA==", "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTY3Mi0xNzIyMjUwMzY4LjEyOTg3MTAwMA==" ], "host.architecture": [ "x86_64" ], "agent.id": [ "c725ae87-e846-4602-9a08-2c717a3a504b" ], "process.parent.code_signature.trusted": [ true ], "process.command_line.text": [ "\"C:\\Windows\\System32\\inetsrv\\appcmd.exe\" list apppool WsusPool /text:*" ], "process.Ext.relative_file_creation_time": [ 185444653.4212362 ], "process.parent.thread.Ext.call_stack_contains_unbacked": [ true ], "user.name": [ "robert.baratheon" ], "process.working_directory": [ "C:\\Windows\\System32\\inetsrv\\" ], "process.entity_id": [ "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTU3MDgtMTcyMjQ0MDg5Mi40MzU1Mzc0MDA=" ], "process.parent.code_signature.status": [ "trusted" ], "host.ip": [ "192.168.56.10", "192.168.133.195", "127.0.0.1", "::1" ], "process.executable.caseless": [ "c:\\windows\\system32\\inetsrv\\appcmd.exe" ], "agent.type": [ "endpoint" ], "process.pe.original_file_name": [ "appcmd.exe" ], "process.executable.text": [ "C:\\Windows\\System32\\inetsrv\\appcmd.exe" ], "process.parent.thread.Ext.call_stack.protection": [ "RWX" ], "user.domain": [ "SEVENKINGDOMS" ], "host.id": [ "bb11c0d0-189a-4fad-aa85-e71a5b6c7ed9" ], "process.name.caseless": [ "appcmd.exe" ], "process.Ext.token.integrity_level_name": [ "high" ], "process.parent.name.caseless": [ "powershell.exe" ], "process.working_directory.text": [ "C:\\Windows\\System32\\inetsrv\\" ], "process.Ext.session_info.user_flags": [ "LOGON_EXTRA_SIDS", "LOGON_WINLOGON" ], "process.code_signature.status": [ "trusted" ], "host.os.Ext.variant": [ "Windows Server 2019 Datacenter Evaluation" ], "event.action": [ "start" ], "event.ingested": [ "2024-07-31T15:48:42Z" ], "@timestamp": [ "2024-07-31T15:48:12.435Z" ], "host.os.platform": [ "windows" ], "process.parent.command_line.caseless": [ "\"c:\\windows\\system32\\windowspowershell\\v1.0\\powershell.exe\" " ], "data_stream.dataset": [ "endpoint.events.process" ], "process.Ext.code_signature": [ { "trusted": [ true ], "subject_name": [ "Microsoft Windows" ], "exists": [ true ], "status": [ "trusted" ] } ], "process.hash.sha1": [ "fcd71b4916276d196f460b0a976efbb8adf3ec63" ], "event.id": [ "NeRojTexa6/KxECF++++lFIa" ], "host.os.name.caseless": [ "windows" ], "process.parent.thread.Ext.call_stack.symbol_info": [ "C:\\Windows\\System32\\ntdll.dll!ZwCreateUserProcess+0x14", "C:\\Windows\\System32\\KernelBase.dll!CreateProcessInternalW+0x1f12", "C:\\Windows\\System32\\KernelBase.dll!CreateProcessW+0x66", "C:\\Windows\\System32\\kernel32.dll!CreateProcessW+0x53", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x334376", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x2b65a0", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System\\97ca54a1c8839381ba1ed5463f15c706\\System.ni.dll+0x2b5f47", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf7fc5b", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xed9f9d", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf5cb0e", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0xf5c7eb", "C:\\Windows\\assembly\\NativeImages_v4.0.30319_64\\System.Manaa57fc8cc#\\c14ebad3ad3b35f8d690b67e24b08072\\System.Management.Automation.ni.dll+0x104fca4", "Unbacked+0x3211" ], "user.name.text": [ "robert.baratheon" ], "process.Ext.session_info.authentication_package": [ "Kerberos" ], "process.name.text": [ "appcmd.exe" ], "host.os.full": [ "Windows Server 2019 Datacenter Evaluation 1809 (10.0.17763.1935)" ], "process.parent.thread.Ext.call_stack.callsite_leading_bytes": [ "2428f6c1017404488b49ffe8af9b5d5f4889442430498bd5448b44245c4c8b4c2448488b6c244048896c2420488b6c243848896c2428488d4b08488b09ff5318" ], "process.pid": [ 5708 ], "process.code_signature.subject_name": [ "Microsoft Windows" ], "process.parent.entity_id": [ "YzcyNWFlODctZTg0Ni00NjAyLTlhMDgtMmM3MTdhM2E1MDRiLTEwMTkyLTE3MjI0NDA2ODMuMzEzOTUwOTAw" ], "host.os.name": [ "Windows" ], "host.name": [ "kingslanding" ], "event.kind": [ "event" ], "process.parent.thread.Ext.call_stack.callsite_trailing_bytes": [ "834648fab8010000004883c4685b5d5e5f415c415d415e415fc3e8c02a945fcc0000001910090010c20c300b500a60097008c006d004e002f000004000000000" ], "process.code_signature.trusted": [ true ], "process.Ext.session_info.relative_logon_time": [ 147713.5745794 ], "process.Ext.session_info.relative_password_age": [ 1815857.0507085 ], "process.parent.thread.Ext.call_stack_summary": [ "ntdll.dll|kernelbase.dll|kernel32.dll|system.ni.dll|system.management.automation.ni.dll|Unbacked" ], "data_stream.type": [ "logs" ], "process.parent.args_count": [ 1 ], "process.Ext.token.security_attributes": [ "TSA://ProcUnique" ], "process.name": [ "appcmd.exe" ], "ecs.version": [ "8.10.0" ], "process.parent.executable.text": [ "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" ], "event.created": [ "2024-07-31T15:48:12.435Z" ], "agent.version": [ "8.14.2" ], "host.os.family": [ "windows" ], "process.Ext.session_info.id": [ 1 ], "process.Ext.mitigation_policies": [ "CF Guard" ], "process.parent.code_signature.exists": [ true ], "process.parent.name.text": [ "powershell.exe" ], "event.sequence": [ 1478750 ], "event.module": [ "endpoint" ], "host.os.kernel": [ "1809 (10.0.17763.1935)" ], "process.Ext.relative_file_name_modify_time": [ 101645988.4863966 ], "host.os.full.caseless": [ "windows server 2019 datacenter evaluation 1809 (10.0.17763.1935)" ], "process.executable": [ "C:\\Windows\\System32\\inetsrv\\appcmd.exe" ], "process.parent.code_signature.subject_name": [ "Microsoft Windows" ], "process.parent.executable.caseless": [ "c:\\windows\\system32\\windowspowershell\\v1.0\\powershell.exe" ], "process.parent.executable": [ "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" ], "process.working_directory.caseless": [ "c:\\windows\\system32\\inetsrv\\" ], "process.parent.command_line.text": [ "\"C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe\" " ], "process.args_count": [ 5 ], "data_stream.namespace": [ "default" ], "process.parent.Ext.code_signature": [ { "trusted": [ true ], "subject_name": [ "Microsoft Windows" ], "exists": [ true ], "status": [ "trusted" ] } ], "process.args": [ "C:\\Windows\\System32\\inetsrv\\appcmd.exe", "list", "apppool", "WsusPool", "/text:*" ], "message": [ "Endpoint process event" ], "process.Ext.authentication_id": [ "0x2e8b75f" ], "process.Ext.token.elevation_level": [ "full" ], "process.parent.args": [ "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe" ], "process.pe.imphash": [ "0c59ba75971a266506603cef51da9ceb" ], "event.type": [ "start" ], "process.command_line": [ "\"C:\\Windows\\System32\\inetsrv\\appcmd.exe\" list apppool WsusPool /text:*" ], "process.Ext.session_info.logon_type": [ "Interactive" ], "event.dataset": [ "endpoint.events.process" ] } } ```