t1556-007-hybrid-identity

name	T1556.007_hybrid-identity
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 credent...
category	authentication
version	18.1
author	cyberstrike-official
tags	["mitre-attack","enterprise","t1556.007","credential-access","defense-evasion","persistence","windows","saas","iaas","office-suite","identity-provider","sub-technique"]
technique_id	T1556.007
tactic	credential-access
all_tactics	["credential-access","defense-evasion","persistence"]
platforms	["Windows","SaaS","IaaS","Office Suite","Identity Provider"]
mitre_url	https://attack.mitre.org/techniques/T1556/007
tech_stack	["windows","saas","cloud","office","identity"]
cwe_ids	["CWE-522"]
chains_with	["T1556","T1556.001","T1556.002","T1556.003","T1556.004","T1556.005","T1556.006","T1556.008","T1556.009"]
prerequisites	["T1556"]
severity_boost	{"T1556":"Chain with T1556 for deeper attack path","T1556.001":"Chain with T1556.001 for deeper attack path","T1556.002":"Chain with T1556.002 for deeper attack path"}

T1556.007 Hybrid Identity

Sub-technique of: T1556

High-Level 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:

• 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. 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.

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.

Kill Chain Phase

• Credential Access (TA0006)
• Defense Evasion (TA0005)
• Persistence (TA0003)

Platforms: Windows, SaaS, IaaS, Office Suite, Identity Provider

What to Check

• Identify if Hybrid Identity technique is applicable to target environment