Unusual Instance Metadata Service (IMDS) API Request

This rule identifies potentially malicious processes attempting to access the cloud service provider’s instance metadata service (IMDS) API endpoint, which can be used to retrieve sensitive instance-specific information such as instance ID, public IP address, and even temporary security credentials if role’s are assumed by that instance. The rule monitors for various tools and scripts like curl, wget, python, and perl that might be used to interact with the metadata API.

Rule type: eql

Rule indices:

logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://hackingthe.cloud/aws/general-knowledge/intro_metadata_service/

Tags:

Domain: Endpoint
OS: Linux
Use Case: Threat Detection
Tactic: Credential Access
Tactic: Discovery
Data Source: Elastic Defend

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

edit

sequence by host.id,  process.parent.entity_id with maxspan=1s
[process where host.os.type == "linux" and event.type == "start" and event.action == "exec" and process.name : (
    "curl", "wget", "python*", "perl*", "php*", "ruby*", "lua*", "telnet", "pwsh",
    "openssl", "nc", "ncat", "netcat", "awk", "gawk", "mawk", "nawk", "socat", "node"
    ) or process.executable : (
      "./*", "/tmp/*", "/var/tmp/*", "/var/www/*", "/dev/shm/*", "/etc/init.d/*", "/etc/rc*.d/*",
      "/etc/cron*", "/etc/update-motd.d/*", "/boot/*", "/srv/*", "/run/*", "/etc/rc.local"
    ) or
    process.command_line: "*169.254.169.254*" and
    not process.working_directory: (
      "/opt/rapid7*",
      "/opt/nessus*",
      "/snap/amazon-ssm-agent*",
      "/srv/snp/docker/overlay2*",
      "/var/log/amazon/ssm*"
    )]
[network where host.os.type == "linux" and event.action == "connection_attempted" and destination.ip == "169.254.169.254"]

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Credential Access
- ID: TA0006
- Reference URL: https://attack.mitre.org/tactics/TA0006/
Technique:
- Name: Unsecured Credentials
- ID: T1552
- Reference URL: https://attack.mitre.org/techniques/T1552/
Sub-technique:
- Name: Cloud Instance Metadata API
- ID: T1552.005
- Reference URL: https://attack.mitre.org/techniques/T1552/005/
Tactic:
- Name: Discovery
- ID: TA0007
- Reference URL: https://attack.mitre.org/tactics/TA0007/
Technique:
- Name: Cloud Infrastructure Discovery
- ID: T1580
- Reference URL: https://attack.mitre.org/techniques/T1580/

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