Hybrid Identity

Executive Summary

Hybrid Identity (T1556.007) is a MITRE ATT&CK technique associated with Defense Impairment, Persistence, Credential Access. Adversaries may patch, modify, or otherwise backdoor cloud authentication processes that are tied to on-premises user identities in order to bypass typical authentication mechanisms, access credentials, and enable persistent access to accounts.

Why Attackers Use It

Attackers use Hybrid Identity because it provides a reliable way to advance their objective within the Defense Impairment, Persistence, Credential Access tactic, often with a favorable balance of impact versus detectability on IaaS, Identity Provider, Office Suite, SaaS, Windows 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 patch, modify, or otherwise backdoor cloud authentication processes that are tied to on-premises user identities in order to bypass typical authentication mechanisms, access credentials, and enable persistent access to accounts.

Many organizations maintain hybrid user and device identities that are shared between on-premises and cloud-based environments. These can be maintained in a number of ways. For example, Microsoft Entra ID includes three options for synchronizing identities between Active Directory and Entra ID(Citation: Azure AD Hybrid Identity):

• Password Hash Synchronization (PHS), in which a privileged on-premises account synchronizes user password hashes between Active Directory and Entra ID, allowing authentication to Entra ID to take place entirely in the cloud
• Pass Through Authentication (PTA), in which Entra ID authentication attempts are forwarded to an on-premises PTA agent, which validates the credentials against Active Directory
• Active Directory Federation Services (AD FS), in which a trust relationship is established between Active Directory and Entra ID

AD FS can also be used with other SaaS and cloud platforms such as AWS and GCP, which will hand off the authentication process to AD FS and receive a token containing the hybrid users’ identity and privileges.

By modifying authentication processes tied to hybrid identities, an adversary may be able to establish persistent privileged access to cloud resources. For example, adversaries who compromise an on-premises server running a PTA agent may inject a malicious DLL into the AzureADConnectAuthenticationAgentService process that authorizes all attempts to authenticate to Entra ID, as well as records user credentials.(Citation: Azure AD Connect for Read Teamers)(Citation: AADInternals Azure AD On-Prem to Cloud) In environments using AD FS, an adversary may edit the Microsoft.IdentityServer.Servicehost configuration file to load a malicious DLL that generates authentication tokens for any user with any set of claims, thereby bypassing multi-factor authentication and defined AD FS policies.(Citation: MagicWeb)

In some cases, adversaries may be able to modify the hybrid identity authentication process from the cloud. For example, adversaries who compromise a Global Administrator account in an Entra ID tenant may be able to register a new PTA agent via the web console, similarly allowing them to harvest credentials and log into the Entra ID environment as any user.(Citation: Mandiant Azure AD Backdoors)

Attack Flow

1. Attacker gains the prerequisite access or context described below.
2. Attacker executes Hybrid Identity to achieve its tactical objective (Defense Impairment, Persistence, Credential Access).
3. Resulting access/data/effect is leveraged to advance the broader attack chain (see Related Techniques).

Prerequisites

• Platform(s): IaaS, Identity Provider, Office Suite, SaaS, Windows
• 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 Hybrid Identity. 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 Hybrid Identity 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

• M1032 -- Multi-factor Authentication: Multi-Factor Authentication (MFA) enhances security by requiring users to provide at least two forms of verification to prove their identity before granting access.
• M1047 -- Audit: Auditing is the process of recording activity and systematically reviewing and analyzing the activity and system configurations.
• M1026 -- Privileged Account Management: Privileged Account Management focuses on implementing policies, controls, and tools to securely manage privileged accounts (e.g., SYSTEM, root, or administrative accounts).

Related Techniques

• T1556