# AS-REP Roasting ## Configuring ### Prerequisite {% content-ref url="/pages/fcJpYDAkCr8gq4FZdjWc" %} [Password spraying](/building-a-windows-ad-lab/vulnerabilities-and-misconfigurations-and-attacks/active-directory-attacks/password-spraying.md) {% endcontent-ref %} ### Configuring 1. Login on `DC02` with the username `Administrator` and password `Welcome01!`. 2. Open the "Active Directory Users and Computers" administration tool on `DC02`.
3\. Click on "View" and enable "Advanced Features".
4\. Open "Users", right click the user `banktest` and click on "Properties" 5\. Open "Account" and scroll to the bottom in "Account options", then select "Do not require kerberos preauthentication".
6\. Click on "Apply" and "OK". ## Attacking ### How it works When pre-authentication is not required, an attack can directly send a request for authentication. The KDC will return an encrypted TGT and the attacker can extract the hash and brute-force it offline. ### Tools * [Crackmapexec](https://github.com/byt3bl33d3r/CrackMapExec) ### Executing the attack AS-REP roasting was already covered in the Initial Access Attacks section. {% content-ref url="/pages/fBAwcQwf43xhEL23msGy" %} [AS-REP Roasting](/building-a-windows-ad-lab/vulnerabilities-and-misconfigurations-and-attacks/initial-access-attacks/username-enumeration/as-rep-roasting.md) {% endcontent-ref %} But since we have a set of valid credentials of the domain now, we could request a list of all usernames and check for AS-REP roastable users. During the Initial Access AS-REP Roasting we used a example script from Impacket. But there are more tools that can accomplish the same thing, such as Crackmapexec. 1. Use the discovered credentials `john` and password `Welcome2022!` with crackmapexec to authenticate over ldap and AS-REP roast all roastable users. ``` crackmapexec ldap 10.0.0.3 -u john -p Welcome2022! --asreproast asreproast.txt ```
2\. We retrieved two hashes, one new one from `bankuser`. Lets crack it with hashcat and use the passwordlist we created earlier during the passwordspray. The hashcat parameters are: * Crackingmode: `-a 0` for using a wordlist * Hashmode: `-m 18200` for Kerberos 5, etype 23, AS-REP * List with hashes: `asreproasting.txt` * Passwords list: `passwords.txt` ``` hashcat -a 0 -m 18200 asreproast.txt passwords.txt ``` ![](/files/gDWTgHTegH7Ti0h9ldA9) We successfully cracked the password of the user `bankuser`, the password is `Bank2022!`. ## Defending ### Recommendations * Periodically check for users that don't require pre-authentication and remove the attribute. Check for users with the attribute: ``` Get-ADUser -Filter {DoesNotRequirePreAuth -eq $true} | Select-Object samAccountName ``` Remove the attribute for a single user: ``` Set-ADAccountControl -DoesNotRequirePreAuth $false -Identity ``` Check for users with the attribute and remove it: ``` Get-ADUser -Filter {DoesNotRequirePreAuth -eq $true} | Set-ADAccountControl -DoesNotRequirePreAuth $false ``` * If pre authenticatio is required. Use strong passwords (at least 32 characters). ### Detection ## References {% embed url="" %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://ad-lab.gitbook.io/building-a-windows-ad-lab/vulnerabilities-and-misconfigurations-and-attacks/active-directory-attacks/page-3.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.