> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/weakly-encrypted-kerberos-tgt-response.md).

# Weakly-Encrypted Kerberos TGT Response

### Synopsis

| Field                | Value                                                                                                   |
| -------------------- | ------------------------------------------------------------------------------------------------------- |
| Activation Period    | 14 Days                                                                                                 |
| Training Period      | 30 Days                                                                                                 |
| Test Period          | N/A (single event)                                                                                      |
| Deduplication Period | 1 Day                                                                                                   |
| Required Data        | <p>Requires one of the following data sources:<br>Palo Alto Networks Firewall EAL Logs OR XDR Agent</p> |
| ATT\&CK Tactic       | Credential Access (TA0006), Persistence (TA0003), Defense Impairment (TA0112)                           |
| ATT\&CK Technique    | Modify Authentication Process: Domain Controller Authentication (T1556.001)                             |
| Severity             | Informational                                                                                           |

### Description

A weakly encrypted Kerberos TGT was issued by a domain controller. The encryption type is abnormal for this DC and results in a TGT that is easier to crack. This behavior may indicate a Skeleton Key attack.

### Attacker's Goals

Manipulate the domain controller authentication process to bypass standard authentication and gain access to hosts and resources in environments relying on single-factor authentication.

### Investigative actions

* Identify the user or entity that requested the TGT during the alert timeframe.
* Determine whether a legitimate service or application requested weak Kerberos encryption.
* Verify whether the domain controller is patched against the Skeleton Key vulnerability (CVE-2016-1567).

### Variations

<details>

<summary>Abnormal Weakly-Encrypted Kerberos TGT Response</summary>

**Synopsis**

| Field             | Value                                                                         |
| ----------------- | ----------------------------------------------------------------------------- |
| ATT\&CK Tactic    | Credential Access (TA0006), Persistence (TA0003), Defense Impairment (TA0112) |
| ATT\&CK Technique | Modify Authentication Process: Domain Controller Authentication (T1556.001)   |
| Severity          | Low                                                                           |

**Description**

A weakly encrypted Kerberos TGT was issued by a domain controller. The encryption type is abnormal for this DC and results in a TGT that is easier to crack. This behavior may indicate a Skeleton Key attack.

**Attacker's Goals**

Manipulate the domain controller authentication process to bypass standard authentication and gain access to hosts and resources in environments relying on single-factor authentication.

**Investigative actions**

* Identify the user or entity that requested the TGT during the alert timeframe.
* Determine whether a legitimate service or application requested weak Kerberos encryption.
* Verify whether the domain controller is patched against the Skeleton Key vulnerability (CVE-2016-1567).

</details>


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