Mika Ayenson
a52751494e
* Convert config header to setup in note field * Parse note field into separate setup and note field with marko gfm * only validate and parse note on elastic authored rules and add CLI description for new DR_BYPASS_NOTE_VALIDATION_AND_PARSE environment variable Co-authored-by: brokensound77 <brokensound77@users.noreply.github.com>
102 lines
5.0 KiB
TOML
102 lines
5.0 KiB
TOML
[metadata]
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creation_date = "2020/09/03"
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maturity = "production"
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updated_date = "2022/05/09"
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[rule]
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author = ["Elastic"]
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description = "Identifies the Windows Defender configuration utility (MpCmdRun.exe) being used to download a remote file."
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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 = "Remote File Download via MpCmdRun"
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note = """## Triage and analysis
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### Investigating Remote File Download via MpCmdRun
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Attackers commonly transfer tooling or malware from external systems into a compromised environment using the command
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and control channel. However, they can also abuse signed utilities to drop these files.
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The `MpCmdRun.exe` is a command-line tool part of Windows Defender and is used to manage various Microsoft Windows
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Defender Antivirus settings and perform certain tasks. It can also be abused by attackers to download remote files,
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including malware and offensive tooling. This rule looks for the patterns used to perform downloads using the utility.
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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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- Identify the user account that performed the action and whether it should perform this kind of action.
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- Contact the account owner and confirm whether they are aware of this activity.
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- Investigate other alerts associated with the user/host during the past 48 hours.
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- Check the reputation of the domain or IP address used to host the downloaded file.
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- Retrieve the file 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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### 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 host 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://twitter.com/mohammadaskar2/status/1301263551638761477",
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"https://www.bleepingcomputer.com/news/microsoft/microsoft-defender-can-ironically-be-used-to-download-malware/",
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]
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risk_score = 47
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rule_id = "c6453e73-90eb-4fe7-a98c-cde7bbfc504a"
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severity = "medium"
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tags = ["Elastic", "Host", "Windows", "Threat Detection", "Command and Control"]
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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 == "start" and
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(process.name : "MpCmdRun.exe" or process.pe.original_file_name == "MpCmdRun.exe") and
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process.args : "-DownloadFile" and process.args : "-url" and process.args : "-path"
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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 = "T1105"
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name = "Ingress Tool Transfer"
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reference = "https://attack.mitre.org/techniques/T1105/"
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[rule.threat.tactic]
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id = "TA0011"
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name = "Command and Control"
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reference = "https://attack.mitre.org/tactics/TA0011/"
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