Emerging Attacker Exploit: Microsoft Cross-Tenant Synchronization
Aug 10, 2023
Threat Detection / Attack Signal
Attackers continue to target Microsoft identities to gain access to connected Microsoft applications and federated SaaS applications. Additionally, attackers continue to progress their attacks in these environments, not by exploiting vulnerabilities, but by abusing native Microsoft functionality to achieve their objective. The attacker group Nobelium, linked with the SolarWinds attacks, has been documented using native functionality like the creation of Federated Trusts [1] to enable persistent access to a Microsoft tenant. This article demonstrates an additional native functionality that when leveraged by an attacker enables persistent access to a Microsoft cloud tenant and lateral movement capabilities to another tenant. This attack vector enables an attacker operating in a compromised tenant to abuse a misconfigured Cross-Tenant Synchronization (CTS) configuration and gain access to other connected tenants or deploy a rogue CTS configuration to maintain persistence with...
