Query: explain T1558.004 AS-REP Roasting
Matching passage: T1558.004 AS-REP Roasting. Tactics: credential access. Description: Adversaries may reveal credentials of accounts that have disabled Kerberos preauthentication by [Password Cracking](https://attack.mitre.org/techniques/T1110/002) Kerberos messages.(Citation: Harmj0y Roasting AS-REPs Jan 2017) Preauthentication offers protection against offline [Password Cracking](https://attack.mitre.org/techniques/T1110/002). When enabled, a user requesting access to a resource initiates communication with the Domain Controller (DC) by sending an Authentication Server Request (AS-REQ) message with a timestamp that is encrypted with the hash of their password. If and only if the DC is able to successfully decrypt the timestamp with the hash of the user’s password, it will then send an Authentication Server Response (AS-REP) message that contains the Ticket Granting Ticket (TGT) to the user. Part of the AS-REP message is signed with the user’s password.(Citation: Microsoft Kerberos Preauth 2014) For each account found without preauthentication, an adversary may send an AS-REQ message without the encrypted timestamp and receive an AS-REP message with TGT data which may be encrypted with an insecure algorithm such as RC4. The recovered encrypted data may be vulnerable to offline [Password Cracking](https://attack.mitre.org/techniques/T1110/002) attacks similarly to [Kerberoasting](https://attack.mitre.org/techniques/T1558/003) and expose plaintext credentials. (Citation: Harmj0y Roasting AS-REPs Jan 2017)(Citation: Stealthbits Cracking AS-REP Roasting Jun 2019) An account registered to a domain, with or without special privileges, can be abused to list all domain accounts that have preauthentication disabled by utilizing Windows tools like [PowerShell](https://attack.mitre.org/techniques/T1059/001) with an LDAP filter. Alternatively, the adversary may send an AS-REQ message for each user. If the DC responds without errors, the account does not require preauthentication and the AS-REP message will already contain the encrypted data. (Citation: Harmj0y
Near-miss passage: T1558.005 Ccache Files. Tactics: credential access. Description: Adversaries may attempt to steal Kerberos tickets stored in credential cache files (or ccache). These files are used for short term storage of a user's active session credentials. The ccache file is created upon user authentication and allows for access to multiple services without the user having to re-enter credentials. The <code>/etc/krb5.conf</code> configuration file and the <code>KRB5CCNAME</code> environment variable are used to set the storage location for ccache entries. On Linux, credentials are typically stored in the `/tmp` directory with a naming format of `krb5cc_%UID%` or `krb5.ccache`. On macOS, ccache entries are stored by default in memory with an `API:{uuid}` naming scheme. Typically, users interact with ticket storage using <code>kinit</code>, which obtains a Ticket-Granting-Ticket (TGT) for the principal; <code>klist</code>, which lists obtained tickets currently held in the credentials cache; and other built-in binaries.(Citation: Kerberos GNU/Linux)(Citation: Binary Defense Kerberos Linux) Adversaries can collect tickets from ccache files stored on disk and authenticate as the current user without their password to perform [Pass the Ticket](https://attack.mitre.org/techniques/T1550/003) attacks. Adversaries can also use these tickets to impersonate legitimate users with elevated privileges to perform [Privilege Escalation](https://attack.mitre.org/tactics/TA0004). Tools like Kekeo can also be used by adversaries to convert ccache files to Windows format for further [Lateral Movement](https://attack.mitre.org/tactics/TA0008). On macOS, adversaries may use open-source tools or the Kerberos framework to interact with ccache files and extract TGTs or Service Tickets via lower-level APIs.(Citation: SpectorOps Bifrost Kerberos macOS 2019)(Citation: Linux Kerberos Tickets)(Citation: Brining MimiKatz to Unix)(Citation: Kekeo)