Remote Execution via File Shares

  1[metadata]
  2creation_date = "2020/11/03"
  3integration = ["endpoint"]
  4maturity = "production"
  5updated_date = "2024/09/23"
  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 = """
 36Identifies the execution of a file that was created by the virtual system process. This may indicate lateral movement
 37via network file shares.
 38"""
 39from = "now-9m"
 40index = ["logs-endpoint.events.process-*", "logs-endpoint.events.file-*"]
 41language = "eql"
 42license = "Elastic License v2"
 43name = "Remote Execution via File Shares"
 44note = """## Triage and analysis
 45
 46### Investigating Remote Execution via File Shares
 47
 48Adversaries can use network shares to host tooling to support the compromise of other hosts in the environment. These tools can include discovery utilities, credential dumpers, malware, etc.
 49
 50> **Note**:
 51> This investigation guide uses the [Osquery Markdown Plugin](https://www.elastic.co/guide/en/security/master/invest-guide-run-osquery.html) introduced in Elastic Stack version 8.5.0. Older Elastic Stack versions will display unrendered Markdown in this guide.
 52
 53#### Possible investigation steps
 54
 55- 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.
 56- Review adjacent login events (e.g., 4624) in the alert timeframe to identify the account used to perform this action.
 57- Investigate other alerts associated with the user/host during the past 48 hours.
 58- Examine the host for derived artifacts that indicate suspicious activities:
 59  - Analyze the process executable using a private sandboxed analysis system.
 60  - Observe and collect information about the following activities in both the sandbox and the alert subject host:
 61    - Attempts to contact external domains and addresses.
 62      - Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process' `process.entity_id`.
 63      - Examine the DNS cache for suspicious or anomalous entries.
 64        - $osquery_0
 65    - Use the Elastic Defend registry events to examine registry keys accessed, modified, or created by the related processes in the process tree.
 66    - Examine the host services for suspicious or anomalous entries.
 67      - $osquery_1
 68      - $osquery_2
 69      - $osquery_3
 70  - 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.
 71- Investigate potentially compromised accounts. Analysts can do this by searching for login events (for example, 4624) to the target host after the registry modification.
 72
 73### False positive analysis
 74
 75- This activity can happen legitimately. Consider adding exceptions if it is expected and noisy in your environment.
 76
 77### Response and remediation
 78
 79- Initiate the incident response process based on the outcome of the triage.
 80- Isolate the involved host to prevent further post-compromise behavior.
 81- If the triage identified malware, search the environment for additional compromised hosts.
 82  - Implement temporary network rules, procedures, and segmentation to contain the malware.
 83  - Stop suspicious processes.
 84  - Immediately block the identified indicators of compromise (IoCs).
 85  - Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that attackers could use to reinfect the system.
 86- Remove and block malicious artifacts identified during triage.
 87- Review the privileges needed to write to the network share and restrict write access as needed.
 88- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and malware components.
 89- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
 90- 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).
 91"""
 92references = [
 93    "http://web.archive.org/web/20230329172636/https://blog.menasec.net/2020/08/new-trick-to-detect-lateral-movement.html",
 94    "https://www.elastic.co/security-labs/hunting-for-lateral-movement-using-event-query-language",
 95]
 96risk_score = 47
 97rule_id = "ab75c24b-2502-43a0-bf7c-e60e662c811e"
 98severity = "medium"
 99tags = [
100    "Domain: Endpoint",
101    "OS: Windows",
102    "Use Case: Threat Detection",
103    "Tactic: Lateral Movement",
104    "Resources: Investigation Guide",
105    "Data Source: Elastic Endgame",
106    "Data Source: Elastic Defend",
107]
108type = "eql"
109
110query = '''
111sequence with maxspan=1m
112  [file where host.os.type == "windows" and event.type in ("creation", "change") and 
113   process.pid == 4 and (file.extension : "exe" or file.Ext.header_bytes : "4d5a*")] by host.id, file.path
114  [process where host.os.type == "windows" and event.type == "start" and
115    not (
116      /* Veeam related processes */
117      (
118        process.name : (
119          "VeeamGuestHelper.exe", "VeeamGuestIndexer.exe", "VeeamAgent.exe", "VeeamLogShipper.exe", "Veeam.VSS.Sharepoint20??.exe"
120        ) and process.code_signature.trusted == true and process.code_signature.subject_name : "Veeam Software Group GmbH"
121      ) or
122      /* PDQ related processes */
123      (
124        process.name : (
125          "PDQInventoryScanner.exe", "PDQInventoryMonitor.exe", "PDQInventory-Scanner-?.exe",
126          "PDQInventoryWakeCommand-?.exe", "PDQDeployRunner-?.exe"
127        ) and process.code_signature.trusted == true and process.code_signature.subject_name : "PDQ.com Corporation"
128      ) or
129      /* CrowdStrike related processes */
130      (
131        (process.executable : "?:\\Windows\\System32\\drivers\\CrowdStrike\\*-WindowsSensor.*.exe" and 
132         process.code_signature.trusted == true and process.code_signature.subject_name : "CrowdStrike, Inc.") or
133        (process.executable : "?:\\Windows\\System32\\drivers\\CrowdStrike\\*-CsInstallerService.exe" and 
134         process.code_signature.trusted == true and process.code_signature.subject_name : "Microsoft Windows Hardware Compatibility Publisher")
135      ) or
136      /* MS related processes */
137      (
138        process.executable == "System" or
139        (process.executable : "?:\\Windows\\ccmsetup\\ccmsetup.exe" and 
140         process.code_signature.trusted == true and process.code_signature.subject_name : "Microsoft Corporation")
141      ) or
142      /* CyberArk processes */
143      (
144        process.executable : "?:\\Windows\\CAInvokerService.exe" and 
145        process.code_signature.trusted == true and process.code_signature.subject_name : "CyberArk Software Ltd."
146      )  or
147      /* Sophos processes */
148      (
149        process.executable : "?:\\ProgramData\\Sophos\\AutoUpdate\\Cache\\sophos_autoupdate1.dir\\SophosUpdate.exe" and 
150        process.code_signature.trusted == true and process.code_signature.subject_name : "Sophos Ltd"
151      ) 
152    )
153  ] by host.id, process.executable
154'''
155
156
157[[rule.threat]]
158framework = "MITRE ATT&CK"
159[[rule.threat.technique]]
160id = "T1021"
161name = "Remote Services"
162reference = "https://attack.mitre.org/techniques/T1021/"
163[[rule.threat.technique.subtechnique]]
164id = "T1021.002"
165name = "SMB/Windows Admin Shares"
166reference = "https://attack.mitre.org/techniques/T1021/002/"
167
168
169
170[rule.threat.tactic]
171id = "TA0008"
172name = "Lateral Movement"
173reference = "https://attack.mitre.org/tactics/TA0008/"