Persistence in Entra: The Role of Illicit Consent-Granting and App Backdooring

Read full article here: https://www.slashid.com/blog/entra-app-backdooring/?utm_source=nhimg

Attackers are increasingly exploiting Microsoft Entra ID (formerly Azure AD) by silently injecting high-privilege OAuth grants and backdooring enterprise applications, creating stealthy persistence mechanisms without user interaction. This advanced tactic exposes organizations to long-term risk by granting malicious apps tenant-wide privileges that bypass normal authentication flows.

The Attack Lifecycle

• Initial Access – Adversaries trick users into granting minimal but dangerous OAuth scopes via phishing or exploit misconfigured cloud workloads through SSRF to steal managed identity tokens.

• Consent Injection – Using stolen OAuth tokens, attackers programmatically push tenant-wide AllPrincipals consents through Graph API or CLI, allowing malicious apps to act on behalf of every user without further approval.

• Privilege Escalation – Application manifests are tampered with to add app-only permissions such as Directory.ReadWrite.All, elevating control to full service principal rights.

• Persistence & Evasion – Attackers plant near-permanent client secrets (expiring in 2299 or later), ensuring continuous access that survives revocation attempts.

• Impact – Full directory takeover, exfiltration of user and group data, shadow admin creation, conditional access tampering, and long-term undetected persistence.
  

MITRE ATT&CK Mapping

• T1566 – Phishing for OAuth consent
• T1078.004 – Hijacking valid cloud accounts
• T1550.003 – Misuse of OAuth tokens for stealth
• T1134.003 – Access token manipulation
• T1598.005 – Exploiting app consent mechanics for privilege escalation

Detection Signals

• Monitor Graph API logs for /oauth2PermissionGrants creation or updates.
• Flag any AllPrincipals consentType values.
• Detect suspicious Update application or Add passwordCredential operations.
• Correlate Graph calls with identities that don’t normally execute administrative tasks.

Mitigation Best Practices

• Restrict app consent approval to a small, vetted admin group.
• Enforce Privileged Identity Management (PIM) for consent-related roles.
• Require just-in-time (JIT) approvals for all high-impact roles.
• Automate audits of app manifests and OAuth grants to catch stealthy changes early.

Why This Matters

Illicit consent-granting and app backdooring are among the most dangerous identity persistence techniques in today’s cloud environments. They exploit blind spots in traditional security models that focus on user accounts while leaving non-human identities and OAuth grants under-monitored.

Organizations that don’t adopt zero standing privileges, runtime authorization, and strict consent governance risk handing attackers the ability to silently own their tenants for months or years undetected.