Remote Execution via File Shares
Identifies the execution of a file that was created by the virtual system process. This may indicate lateral movement via network file shares.
Elastic rule (View on GitHub)
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/"
Triage and analysis
Investigating Remote Execution via File Shares
Adversaries 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.
Note: This investigation guide uses the 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.
- Review adjacent login events (e.g., 4624) in the alert timeframe to identify the account used to perform this action.
- Investigate other alerts associated with the user/host during the past 48 hours.
- Examine the host for derived artifacts that indicate suspicious activities:
- Analyze the process executable 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_0
- Use the Elastic Defend network events to determine domains and addresses contacted by the subject process by filtering by the process'
- 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_1
- $osquery_2
- $osquery_3
- Attempts to contact external domains and addresses.
- 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 can happen legitimately. Consider adding exceptions if it is expected and noisy in your environment.
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.
- Review the privileges needed to write to the network share and restrict write access as needed.
- 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).
References
Related rules
- Potential Remote Desktop Tunneling Detected
- Encrypting Files with WinRar or 7z
- Exporting Exchange Mailbox via PowerShell
- Potential Lateral Tool Transfer via SMB Share
- Remote Scheduled Task Creation