Discovery Command Output Written to Suspicious File

Detects when a discovery command is executed followed by the immediate modification of a suspicious file via the same process. Many types of malware execute discovery commands, save the output to a file, and then exfiltrate that file via their C2 channel.

Rule type: eql
Rule indices:

logs-endpoint.events.process-*
logs-endpoint.events.file-*

Rule Severity: medium
Risk Score: 47
Runs every:
Searches indices from: now-9m
Maximum alerts per execution: ?
References:

Tags:

Domain: Endpoint
OS: macOS
Use Case: Threat Detection
Tactic: Collection
Tactic: Discovery
Data Source: Elastic Defend

Version: ?
Rule authors:

Elastic

Rule license: Elastic License v2

Rule Query

		sequence by process.entity_id with maxspan=15s
  [process where host.os.type == "macos" and event.type == "start" and event.action == "exec" and
    process.parent.name in ("bash", "sh", "zsh") and
    process.name in ("whoami", "ifconfig", "system_profiler", "dscl", "arch", "csrutil") and
    process.args_count == 1]
  [file where host.os.type == "macos" and event.action == "modification" and
    file.path like ("/Users/Shared/*", "/tmp/*", "/private/tmp/*", "/Library/WebServer/*",
                    "/Library/Graphics/*", "/Library/Fonts/*", "/private/var/root/Library/HTTPStorages/*", "/*/.*") and
    not file.path like ("/private/tmp/*.fifo", "/private/tmp/tcl-tk*")]
		
	

Framework: MITRE ATT&CK

Tactic:
- Name: Collection
- Id: TA0009
- Reference URL: https://attack.mitre.org/tactics/TA0009/
Technique:
- Name: Data Staged
- Id: T1074
- Reference URL: https://attack.mitre.org/techniques/T1074/
Sub Technique:
- Name: Local Data Staging
- Id: T1074.001
- Reference URL: https://attack.mitre.org/techniques/T1074/001/

Framework: MITRE ATT&CK

Tactic:
- Name: Discovery
- Id: TA0007
- Reference URL: https://attack.mitre.org/tactics/TA0007/
Technique:
- Name: System Information Discovery
- Id: T1082
- Reference URL: https://attack.mitre.org/techniques/T1082/