Terrance DeJesus
107 lines
5.1 KiB
TOML
107 lines
5.1 KiB
TOML
[metadata]
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creation_date = "2020/08/31"
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deprecation_date = "2022/08/03"
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maturity = "deprecated"
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updated_date = "2022/08/03"
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[rule]
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author = ["Elastic"]
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description = "Identifies a suspicious Conhost child process which may be an indication of code injection activity."
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from = "now-9m"
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index = ["winlogbeat-*", "logs-endpoint.events.*", "logs-windows.*"]
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language = "eql"
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license = "Elastic License v2"
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name = "Suspicious Process from Conhost"
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note = """## Triage and analysis
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### Investigating Suspicious Process from Conhost
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The Windows Console Host, or `conhost.exe`, is both the server application for all of the Windows Console APIs as well as
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the classic Windows user interface for working with command-line applications.
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The `conhost.exe` process doesn't normally have child processes. Any processes spawned by the `conhost.exe` process can indicate code
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injection activity or a suspicious process masquerading as the `conhost.exe` process.
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#### Possible investigation steps
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- Investigate the process execution chain (parent process tree) for unknown processes. Examine their executable files
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for prevalence, whether they are located in expected locations, and if they are signed with valid digital signatures.
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- Investigate abnormal behaviors observed by the subject process, such as network connections, registry or file
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modifications, and any spawned child processes.
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- Investigate other alerts associated with the user/host during the past 48 hours.
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- Inspect the host for suspicious or abnormal behaviors in the alert timeframe.
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- Retrieve the process executable and determine if it is malicious:
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- Use a private sandboxed malware analysis system to perform analysis.
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- Observe and collect information about the following activities:
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- Attempts to contact external domains and addresses.
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- File and registry access, modification, and creation activities.
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- Service creation and launch activities.
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- Scheduled tasks creation.
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- Use the PowerShell `Get-FileHash` cmdlet to get the files' SHA-256 hash values.
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- Search for the existence and reputation of the hashes in resources like VirusTotal, Hybrid-Analysis, CISCO Talos, Any.run, etc.
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### Related rules
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- Conhost Spawned By Suspicious Parent Process - 05b358de-aa6d-4f6c-89e6-78f74018b43b
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- Suspicious PowerShell Engine ImageLoad - 852c1f19-68e8-43a6-9dce-340771fe1be3
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### False positive analysis
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- This activity is unlikely to happen legitimately. Benign true positives (B-TPs) can be added as exceptions if necessary.
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### Response and remediation
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- Initiate the incident response process based on the outcome of the triage.
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- Isolate the involved hosts to prevent further post-compromise behavior.
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- If the triage identified malware, search the environment for additional compromised hosts.
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- Implement temporary network rules, procedures, and segmentation to contain the malware.
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- Stop suspicious processes.
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- Immediately block the identified indicators of compromise (IoCs).
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- Inspect the affected systems for additional malware backdoors like reverse shells, reverse proxies, or droppers that
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attackers could use to reinfect the system.
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- Remove and block malicious artifacts identified during triage.
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- Investigate credential exposure on systems compromised or used by the attacker to ensure all compromised accounts are
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identified. Reset passwords for these accounts and other potentially compromised credentials, such as email, business
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systems, and web services.
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- Run a full antimalware scan. This may reveal additional artifacts left in the system, persistence mechanisms, and
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malware components.
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- Determine the initial vector abused by the attacker and take action to prevent reinfection through the same vector.
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- Using the incident response data, update logging and audit policies to improve the mean time to detect (MTTD) and the
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mean time to respond (MTTR).
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## Setup
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If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
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"""
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references = [
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"https://modexp.wordpress.com/2018/09/12/process-injection-user-data/",
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"https://github.com/sbousseaden/EVTX-ATTACK-SAMPLES/blob/master/Defense%20Evasion/evasion_codeinj_odzhan_conhost_sysmon_10_1.evtx",
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]
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risk_score = 73
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rule_id = "28896382-7d4f-4d50-9b72-67091901fd26"
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severity = "high"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Defense Evasion"]
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timestamp_override = "event.ingested"
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type = "eql"
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query = '''
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process where event.type in ("start", "process_started") and
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process.parent.name : "conhost.exe" and
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not process.executable : ("?:\\Windows\\splwow64.exe", "?:\\Windows\\System32\\WerFault.exe", "?:\\Windows\\System32\\conhost.exe")
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'''
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[[rule.threat]]
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framework = "MITRE ATT&CK"
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[[rule.threat.technique]]
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id = "T1055"
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name = "Process Injection"
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reference = "https://attack.mitre.org/techniques/T1055/"
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[rule.threat.tactic]
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id = "TA0005"
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name = "Defense Evasion"
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reference = "https://attack.mitre.org/tactics/TA0005/"
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