Cloud Instance Metadata API

Executive Summary

Cloud Instance Metadata API (T1552.005) is a MITRE ATT&CK technique associated with Credential Access. Adversaries may attempt to access the Cloud Instance Metadata API to collect credentials and other sensitive data.

Why Attackers Use It

Attackers use Cloud Instance Metadata API because it provides a reliable way to advance their objective within the Credential Access tactic, often with a favorable balance of impact versus detectability on IaaS environments. Defenders should assess this behavior in the context of the affected platform and adjacent activity rather than treating it as a standalone indicator.

MITRE Description

Adversaries may attempt to access the Cloud Instance Metadata API to collect credentials and other sensitive data.

Most cloud service providers support a Cloud Instance Metadata API which is a service provided to running virtual instances that allows applications to access information about the running virtual instance. Available information generally includes name, security group, and additional metadata including sensitive data such as credentials and UserData scripts that may contain additional secrets. The Instance Metadata API is provided as a convenience to assist in managing applications and is accessible by anyone who can access the instance.(Citation: AWS Instance Metadata API) A cloud metadata API has been used in at least one high profile compromise.(Citation: Krebs Capital One August 2019)

If adversaries have a presence on the running virtual instance, they may query the Instance Metadata API directly to identify credentials that grant access to additional resources. Additionally, adversaries may exploit a Server-Side Request Forgery (SSRF) vulnerability in a public facing web proxy that allows them to gain access to the sensitive information via a request to the Instance Metadata API.(Citation: RedLock Instance Metadata API 2018)

The de facto standard across cloud service providers is to host the Instance Metadata API at <code>http[:]//169.254.169.254</code>.

Attack Flow

1. Attacker gains the prerequisite access or context described below.
2. Attacker executes Cloud Instance Metadata API to achieve its tactical objective (Credential Access).
3. Resulting access/data/effect is leveraged to advance the broader attack chain (see Related Techniques).

Prerequisites

• Platform(s): IaaS
• ATT&CK does not define one universal permission requirement for this technique. Establish the required access from the observed implementation and affected platform.

Common Tools

• Tool attribution is implementation-specific. Use ATT&CK procedure examples and local telemetry to identify the binaries, services, scripts, accounts, or cloud resources involved.

Commands

No universal command represents Cloud Instance Metadata API. Capture the exact command line, arguments, parent process, account, host, and execution time from the investigated environment; do not operationalize unverified examples.

Network Traffic

• Network observability is implementation-dependent. Review DNS, proxy, firewall, flow, authentication, and packet telemetry around the activity window, then correlate remote endpoints and protocol behavior with host evidence.

Windows Events

Sysmon Events

Detection Opportunities

No MITRE detection guidance published for this technique.

Relevant ATT&CK Data Sources: N/A

Sigma Rules

A universal Sigma rule would create unreliable results because this technique has no single guaranteed observable. Build detection logic from a documented behavior and supported data source, scope it to the affected platform, and validate it against benign administrative activity before deployment.

Splunk Queries

Start with the data sources named in the detection section. Scope searches by asset, identity, and time window; correlate the primary behavior with preceding access and subsequent actions. A portable query is intentionally not provided where the technique lacks a universal schema or observable.

Investigation Workflow

1. Confirm that the observed behavior is consistent with Cloud Instance Metadata API and rule out expected administrative or application activity.
2. Establish the first-seen time, initiating identity, source system, target system, and affected resources.
3. Collect relevant host, identity, network, cloud, and application telemetry for the surrounding time window.
4. Correlate parent and child activity, remote connections, file or configuration changes, and related ATT&CK techniques.
5. Determine scope by searching for the same observable across peer assets and identities.
6. Preserve volatile evidence and record confidence, assumptions, and telemetry gaps before containment.

Containment

1. Isolate affected host(s)/account(s) identified during investigation.
2. Revoke or rotate any credentials/tokens potentially exposed.
3. Apply the mitigations listed below where not already enforced.
4. Validate no related techniques (see Related Techniques) were chained against the same asset.

Mitigation

• M1035 -- Limit Access to Resource Over Network: Restrict access to network resources, such as file shares, remote systems, and services, to only those users, accounts, or systems with a legitimate business requirement.
• M1042 -- Disable or Remove Feature or Program: Disable or remove unnecessary and potentially vulnerable software, features, or services to reduce the attack surface and prevent abuse by adversaries.
• M1037 -- Filter Network Traffic: Employ network appliances and endpoint software to filter ingress, egress, and lateral network traffic.

Related Techniques

• T1046
• T1059.004
• T1078.004
• T1082
• T1105
• T1213.003
• T1528
• T1550.001
• T1552
• T1552.001
• T1613
• T1619