LSASS Process Access via Windows API

  1[metadata]
  2creation_date = "2023/03/02"
  3integration = ["endpoint", "m365_defender"]
  4maturity = "production"
  5updated_date = "2026/05/04"
  6
  7[transform]
  8[[transform.osquery]]
  9label = "Osquery - Retrieve DNS Cache"
 10query = "SELECT * FROM dns_cache"
 11
 12[[transform.osquery]]
 13label = "Osquery - Retrieve All Services"
 14query = "SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services"
 15
 16[[transform.osquery]]
 17label = "Osquery - Retrieve Services Running on User Accounts"
 18query = """
 19SELECT description, display_name, name, path, pid, service_type, start_type, status, user_account FROM services WHERE
 20NOT (user_account LIKE '%LocalSystem' OR user_account LIKE '%LocalService' OR user_account LIKE '%NetworkService' OR
 21user_account == null)
 22"""
 23
 24[[transform.osquery]]
 25label = "Osquery - Retrieve Service Unsigned Executables with Virustotal Link"
 26query = """
 27SELECT concat('https://www.virustotal.com/gui/file/', sha1) AS VtLink, name, description, start_type, status, pid,
 28services.path FROM services JOIN authenticode ON services.path = authenticode.path OR services.module_path =
 29authenticode.path JOIN hash ON services.path = hash.path WHERE authenticode.result != 'trusted'
 30"""
 31
 32
 33[rule]
 34author = ["Elastic"]
 35description = "Identifies access attempts to the LSASS handle, which may indicate an attempt to dump credentials from LSASS memory."
 36from = "now-30m"
 37interval = "15m"
 38language = "esql"
 39license = "Elastic License v2"
 40name = "LSASS Process Access via Windows API"
 41note = """## Triage and analysis
 42
 43### Investigating LSASS Process Access via Windows API
 44
 45The Local Security Authority Subsystem Service (LSASS) is a critical Windows component responsible for managing user authentication and security policies. Adversaries may attempt to access the LSASS handle to dump credentials from its memory, which can be used for lateral movement and privilege escalation.
 46
 47This rule identifies attempts to access LSASS by monitoring for specific API calls (OpenProcess, OpenThread) targeting the "lsass.exe" process.
 48
 49> **Note**:
 50> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/current/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 51
 52### Possible investigation steps
 53
 54- Investigate other alerts associated with the user/host during the past 48 hours.
 55- Investigate the process execution chain (parent process tree) of the process that accessed the LSASS handle.
 56  - Examine their executable files for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
 57  - Determine the first time the process executable was seen in the environment and if this behavior happened in the past.
 58  - Validate the activity is not related to planned patches, updates, network administrator activity, or legitimate software installations.
 59  - Investigate any abnormal behavior by the subject process, such as network connections, DLLs loaded, registry or file modifications, and any spawned child processes.
 60- Assess the access rights (`process.Ext.api.parameters.desired_access`field) requested by the process. This [Microsoft documentation](https://learn.microsoft.com/en-us/windows/win32/procthread/process-security-and-access-rights) may be useful to help the interpretation.
 61- If there are traces of LSASS memory being successfully dumped, investigate potentially compromised accounts. Analysts can do this by searching for login events (e.g., 4624) to the target host.
 62- Examine the host for derived artifacts that indicate suspicious activities:
 63  - Analyze the executables of the processes using a private sandboxed analysis system.
 64  - Observe and collect information about the following activities in both the sandbox and the alert subject host:
 65    - Attempts to contact external domains and addresses.
 66      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process's `process.entity_id`.
 67      - Examine the DNS cache for suspicious or anomalous entries.
 68        - $osquery_0
 69    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
 70    - Examine the host services for suspicious or anomalous entries.
 71      - $osquery_1
 72      - $osquery_2
 73      - $osquery_3
 74  - 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.
 75
 76
 77### False positive analysis
 78
 79- If this rule is noisy in your environment due to expected activity, consider adding exceptions — preferably with a combination of `process.executable`, `process.code_signature.subject_name` and `process.Ext.api.parameters.desired_access_numeric` conditions.
 80
 81### Related Rules
 82
 83- Suspicious Lsass Process Access - 128468bf-cab1-4637-99ea-fdf3780a4609
 84- Potential Credential Access via DuplicateHandle in LSASS - 02a4576a-7480-4284-9327-548a806b5e48
 85- LSASS Memory Dump Handle Access - 208dbe77-01ed-4954-8d44-1e5751cb20de
 86
 87### Response and Remediation
 88
 89- Initiate the incident response process based on the outcome of the triage.
 90  - If malicious activity is confirmed, perform a broader investigation to identify the scope of the compromise and determine the appropriate remediation steps.
 91- Isolate the involved host to prevent further post-compromise behavior.
 92- If the triage identified malware, search the environment for additional compromised hosts.
 93  - Implement temporary network rules, procedures, and segmentation to contain the malware.
 94  - Stop suspicious processes.
 95  - Immediately block the identified indicators of compromise (IoCs).
 96  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
 97- Remove and block malicious artifacts identified during triage.
 98- 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.
 99- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
100- Reimage the host operating system or restore the compromised files to clean versions.
101- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
102- 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).
103"""
104
105setup = """## Setup
106
107This rule is designed for data generated by [Elastic Defend](https://www.elastic.co/security/endpoint-security), which provides native endpoint detection and response, along with event enrichments designed to work with our detection rules.
108
109Setup instructions: https://ela.st/install-elastic-defend
110
111### Additional data sources
112
113This rule also supports the following third-party data sources. For setup instructions, refer to the links below:
114
115- [Microsoft Defender XDR](https://ela.st/m365-defender)
116"""
117
118references = ["https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1003.001/T1003.001.md"]
119risk_score = 47
120rule_id = "ff4599cb-409f-4910-a239-52e4e6f532ff"
121severity = "medium"
122tags = [
123    "Domain: Endpoint",
124    "OS: Windows",
125    "Use Case: Threat Detection",
126    "Tactic: Credential Access",
127    "Tactic: Execution",
128    "Data Source: Elastic Defend",
129    "Data Source: Microsoft Defender XDR",
130    "Resources: Investigation Guide"
131]
132timestamp_override = "event.ingested"
133type = "esql"
134
135query = '''
136from logs-endpoint.events.api-*, logs-m365_defender.event-* metadata _id, _version, _index
137
138| where event.category == "api" and host.os.family == "windows" and
139   process.Ext.api.name in ("OpenProcess", "OpenThread", "ReadProcessMemory") and
140   Target.process.name == "lsass.exe" and process.executable is not null and
141
142   // Noisy patterns
143   not to_lower(process.executable) like """c:\\program files\\*.exe""" and
144   not to_lower(process.executable) like """c:\\program files (x86)\\*.exe""" and
145   not process.executable like """C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\MsMpEng.exe""" and
146   not process.executable like """C:\\ProgramData\\Microsoft\\Windows Defender\\Platform\\*\\MsMpEng.exe"""
147
148 /* normalize process paths to reduce known random patterns in process.executable */
149| eval Esql.process_path = replace(process.executable, """([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}|ns[a-z][A-Z0-9]{3,4}\.tmp|DX[A-Z0-9]{3,4}\.tmp|7z[A-Z0-9]{3,5}\.tmp|[0-9\.\-\_]{3,})""", "")
150
151// Group by process path
152| stats Esql.access_count = count(*),
153        Esql.count_distinct_hosts = count_distinct(host.id),
154        Esql.host_id_values = VALUES(host.id),
155        Esql.host_name_values = VALUES(host.name),
156        Esql.user_name_values = VALUES(user.name),
157        Esql.process_pid_values = VALUES(process.entity_id),
158        Esql.process_executable_values = VALUES(process.executable),
159        Esql.data_stream_namespace.values = VALUES(data_stream.namespace),
160        Esql.user_name_values = VALUES(user.name) by Esql.process_path
161
162// Limit to rare instances limited to 1 unique host
163| where Esql.count_distinct_hosts == 1 and Esql.access_count <= 3
164
165// Extract the single host ID and process into their corresponding ECS fields for alerts exclusion
166| eval host.id = mv_min(Esql.host_id_values),
167       host.name = mv_min(Esql.host_name_values),
168       process.executable = mv_min(Esql.process_executable_values), 
169       user.name = mv_min(Esql.user_name_values)
170
171// Add the new field to the keep statement
172| keep Esql.*, host.id, host.name, user.name, process.executable
173'''
174
175
176[[rule.threat]]
177framework = "MITRE ATT&CK"
178[[rule.threat.technique]]
179id = "T1003"
180name = "OS Credential Dumping"
181reference = "https://attack.mitre.org/techniques/T1003/"
182[[rule.threat.technique.subtechnique]]
183id = "T1003.001"
184name = "LSASS Memory"
185reference = "https://attack.mitre.org/techniques/T1003/001/"
186
187
188
189[rule.threat.tactic]
190id = "TA0006"
191name = "Credential Access"
192reference = "https://attack.mitre.org/tactics/TA0006/"
193[[rule.threat]]
194framework = "MITRE ATT&CK"
195[[rule.threat.technique]]
196id = "T1106"
197name = "Native API"
198reference = "https://attack.mitre.org/techniques/T1106/"
199
200
201[rule.threat.tactic]
202id = "TA0002"
203name = "Execution"
204reference = "https://attack.mitre.org/tactics/TA0002/"