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Insecure service configuration - Kerberoast

Description

Due to the operation of the Kerberos service it is possible to extract krbtgs hashes of users within the domain.

Impact

Obtain users hashes.

Recommendation

Configure a logger to alert Kerberoast attacks.

Threat

Unauthorized domain user with valid credentials in the internal network.

Expected Remediation Time

⌚ 120 minutes.

Score

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base

  • Attack vector: A
  • Attack complexity: L
  • Privileges required: L
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: N
  • Availability: N

Temporal

  • Exploit code madurity: X
  • Remediation level: X
  • Report confidence: X

Result

  • Vector string: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:X/RL:X/RC:X
  • Score:
    • Base: 3.5
    • Temporal: 3.5
  • Severity:
    • Base: Low
    • Temporal: Low

Code Examples

Compliant code

The service should have a defined security group id, that allows a logger to be activated in case of an attack

Properties:
GroupDescription: Domain Controllers Security Group
VpcId: !Ref VPCID
SecurityGroupIngress:
- IpProtocol: tcp
Description: Kerberos
FromPort: 88
ToPort: 88
SourceSecurityGroupId: !Ref AdminMembersSG

Non compliant code

A Kerberoast service uses the default security group configuration

Properties:
GroupDescription: Domain Controllers Security Group
VpcId: !Ref VPCID
SecurityGroupIngress:
- IpProtocol: tcp
Description: Kerberos
FromPort: 88
ToPort: 88
SourceSecurityGroupId: Allow

Requirements