Potential AS-REP Roasting via Kerberos TGT Requests

Description

Detects suspicious Kerberos TGT requests with pre-authentication disabled (Pre-Authentication Type = 0) and Ticket Encryption Type (0x17) i.e, RC4-HMAC. This may indicate an AS-REP Roasting attack, where attackers request AS-REP messages for accounts without pre-authentication and attempt to crack the encrypted ticket offline to recover user passwords.

Query · sigma

selection:
  EventID: 4768
  TicketEncryptionType: '0x17'
  ServiceName: krbtgt
  PreAuthType: 0
condition: selection

Known false positives

  • Legacy systems or applications that legitimately use RC4 encryption
  • Misconfigured accounts with pre-authentication disabled
Raw source Potential AS-REP Roasting via Kerberos TGT Requests · Sigma
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Published by SigmaHQ/sigma ↗, licensed under Detection Rule License 1.1 ↗. Reproduced here unmodified. 
title: Potential AS-REP Roasting via Kerberos TGT Requests
id: 3e2f1b2c-4d5e-11ee-be56-0242ac120002
status: experimental
description: |
    Detects suspicious Kerberos TGT requests with pre-authentication disabled (Pre-Authentication Type = 0) and Ticket Encryption Type (0x17) i.e, RC4-HMAC.
    This may indicate an AS-REP Roasting attack, where attackers request AS-REP messages for accounts without pre-authentication and attempt to crack the encrypted ticket offline to recover user passwords.
references:
    - https://medium.com/system-weakness/detecting-as-rep-roasting-attacks-b5b3965f9714
    - https://www.picussecurity.com/resource/blog/as-rep-roasting-attack-explained-mitre-attack-t1558.004
author: ANosir
date: 2025-05-22
modified: 2025-07-04
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 4768
        TicketEncryptionType: '0x17'
        ServiceName: 'krbtgt'
        PreAuthType: 0
    condition: selection
falsepositives:
    - Legacy systems or applications that legitimately use RC4 encryption
    - Misconfigured accounts with pre-authentication disabled
level: medium

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