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MITRE ATT&CK · T1649

Steal or Forge Authentication Certificates

MITRE · cited in 7 of our lessons

Explanation

What attackers do. Attackers steal or forge digital certificates used for authentication, for example by abusing misconfigured certificate templates in an enterprise certificate authority or extracting private keys. A certificate can grant long-lived access that survives password resets. This serves Credential Access.

How to defend. Audit certificate authority configuration and templates regularly, restrict enrolment rights, and require manager approval for sensitive templates. Protect certificate authority servers as tier zero assets, store private keys in hardware where possible and monitor certificate issuance.

Signs to look for. Look for certificates requested with unusual subject names, enrolment by accounts that do not normally request certificates, private key exports and authentication with certificates from unexpected hosts. A common gap is that certificate authority logs are rarely collected or reviewed.

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The official text
Adversaries may steal or forge certificates used for authentication to access remote systems or resources. Digital certificates are often used to sign and encrypt messages and/or files. Certificates are also used as authentication material. For example, Entra ID device certificates and Active Directory Certificate Services (AD CS) certificates bind to an identity and can be used as credentials for domain accounts. Authentication certificates can be both stolen and forged. For example, AD CS certificates can be stolen from encrypted storage (in the Registry or files), misplaced certificate files (i.e. Unsecured Credentials), or directly from the Windows certificate store via various crypto APIs. With appropriate enrollment rights, users and/or machines within a domain can also request and/or manually renew certificates from enterprise certificate authorities (CA). This enrollment process defines various settings and permissions associated with the certificate. Of note, the certificate’s extended key usage (EKU) values define signing, encryption, and authentication use cases, while the certificate’s subject alternative name (SAN) values define the certificate owner’s alternate names. Abusing certificates for authentication credentials may enable other behaviors such as Lateral Movement. Certificate-related misconfigurations may also enable opportunities for Privilege Escalation, by way of allowing users to impersonate or assume privileged accounts or permissions via the identities (SANs) associated with a certificate. These abuses may also enable Persistence via stealing or forging certificates that can be used as Valid Accounts for the duration of the certificate's validity, despite user password resets. Authentication certificates can also be stolen and forged for machine accounts.

© The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation (MITRE ATT&CK®).

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