Event 5067: A cryptographic function modification was attempted.

Adversaries may search for private key certificate files on compromised systems for insecurely stored credentials. Private cryptographic keys and certificates are used for authentication, encryption/decryption, and digital signatures.(Citation: Wikipedia Public Key Crypto) Common key and certificate file extensions include: .key, .pgp, .gpg, .ppk., .p12, .pem, .pfx, .cer, .p7b, .asc. Adversaries may also look in common key directories, such as <code>~/.ssh</code> for SSH keys on * nix-based systems or <code>C:&#92;Users&#92;(username)&#92;.ssh&#92;</code> on Windows. Adversary tools may also search compromised systems for file extensions relating to cryptographic keys and certificates.(Citation: Kaspersky Careto)(Citation: Palo Alto Prince of Persia) When a device is registered to Entra ID, a device key and a transport key are generated and used to verify the device’s identity.(Citation: Microsoft Primary Refresh Token) An adversary with access to the device may be able to export the keys in order to impersonate the device.(Citation: AADInternals Azure AD Device Identities) On network devices, private keys may be exported via [Network Device CLI](https://attack.mitre.org/techniques/T1059/008) commands such as `crypto pki export`.(Citation: cisco_deploy_rsa_keys) Some private keys require a password or passphrase for operation, so an adversary may also use [Input Capture](https://attack.mitre.org/techniques/T1056) for keylogging or attempt to [Brute Force](https://attack.mitre.org/techniques/T1110) the passphrase off-line. These private keys can be used to authenticate to [Remote Services](https://attack.mitre.org/techniques/T1021) like SSH or for use in decrypting other collected files such as email.

Adversaries may maliciously modify components of a victim environment in order to hinder or disable defensive mechanisms. This not only involves impairing preventative defenses, such as firewalls and anti-virus, but also detection capabilities that defenders can use to audit activity and identify malicious behavior. This may also span both native defenses as well as supplemental capabilities installed by users and administrators. Adversaries may also impair routine operations that contribute to defensive hygiene, such as blocking users from logging out, preventing a system from shutting down, or disabling or modifying the update process. Adversaries could also target event aggregation and analysis mechanisms, or otherwise disrupt these procedures by altering other system components. These restrictions can further enable malicious operations as well as the continued propagation of incidents.(Citation: Google Cloud Mandiant UNC3886 2024)(Citation: Emotet shutdown)

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.(Citation: O365 Blog Azure AD Device IDs)(Citation: Microsoft AD CS Overview) Authentication certificates can be both stolen and forged. For example, AD CS certificates can be stolen from encrypted storage (in the Registry or files)(Citation: APT29 Deep Look at Credential Roaming), misplaced certificate files (i.e. [Unsecured Credentials](https://attack.mitre.org/techniques/T1552)), or directly from the Windows certificate store via various crypto APIs.(Citation: SpecterOps Certified Pre Owned)(Citation: GitHub CertStealer)(Citation: GitHub GhostPack Certificates) 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.(Citation: Medium Certified Pre Owned) Abusing certificates for authentication credentials may enable other behaviors such as [Lateral Movement](https://attack.mitre.org/tactics/TA0008). Certificate-related misconfigurations may also enable opportunities for [Privilege Escalation](https://attack.mitre.org/tactics/TA0004), 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](https://attack.mitre.org/tactics/TA0003) via stealing or forging certificates that can be used as [Valid Accounts](https://attack.mitre.org/techniques/T1078) for the duration of the certificate's validity, despite user password resets. Authentication certificates can also be stolen and forged for machine accounts. Adversaries who have access to root (or subordinate) CA certificate private keys (or mechanisms protecting/managing these keys) may also establish [Persistence](https://attack.mitre.org/tactics/TA0003) by forging arbitrary authentication certificates for the victim domain (known as “golden” certificates).(Citation: Medium Certified Pre Owned) Adversaries may also target certificates and related services in order to access other forms of credentials, such as [Golden Ticket](https://attack.mitre.org/techniques/T1558/001) ticket-granting tickets (TGT) or NTLM plaintext.(Citation: Medium Certified Pre Owned)