Ensure the KDC does not support DES, 3DES or RC4 encryption types

AltaNivel 1Automatizadakerberos

Descripción

DES and RC4-HMAC (arcfour) keys are crackable and des3-cbc-sha1 is deprecated; principals created with them weaken every ticket. The audit checks the MIT KDC configuration (/etc/krb5kdc/kdc.conf on Debian/Ubuntu, /var/kerberos/krb5kdc/kdc.conf on RHEL) and fails if supported_enctypes or master_key_type names a des, des3, rc4 or arcfour type. When unset, MIT defaults to AES only.

Cómo se verifica

Método de auditoría: Comando de shell

shell

n=0; bad=0
for f in /etc/krb5kdc/kdc.conf /var/kerberos/krb5kdc/kdc.conf; do
  [ -f "$f" ] || continue
  n=$((n+1))
  grep -Eiq '^[[:space:]]*(supported_enctypes|master_key_type)[[:space:]]*=.*(des|rc4|arcfour)' "$f" && { echo "$f lists weak enctypes"; bad=1; }
done
[ "$n" -gt 0 ] && [ "$bad" -eq 0 ] && echo compliant

Salida esperada: compliant

Cómo se corrige

Método de corrección: Guía o parche de infraestructura

In each [realms] entry of kdc.conf set supported_enctypes = aes256-cts-hmac-sha1-96:normal aes128-cts-hmac-sha1-96:normal (add aes256-cts-hmac-sha384-192:normal on 1.15+). Restart krb5kdc and kadmind, then rekey affected principals (kadmin: cpw -randkey / change password) so old DES/RC4 keys are removed; rekeying krbtgt requires planning.

Propiedades

Sistemas operativos: Cualquiera
Etiquetas: kerberoskdccrypto
Referencia: CIS MIT Kerberos / Linux Benchmark guidance - Strong Kerberos encryption types (verify section number for your release)

Verificar este host

Ejecute esto en un equipo que tenga permiso para auditar. El escaneo es de solo lectura.

shell

tmaegis scan --target kerberos