Performing Kerberoasting Attack

Performing Kerberoasting Attack

Legal Notice: This skill is for authorized security testing and educational purposes only. Unauthorized use against systems you do not own or have written permission to test is illegal and may violate computer fraud laws.

Overview

Kerberoasting is a post-exploitation technique that targets service accounts in Active Directory by requesting Kerberos TGS (Ticket Granting Service) tickets for accounts with Service Principal Names (SPNs) set. These tickets are encrypted with the service account's NTLM hash, allowing offline brute-force cracking without generating failed login events. It is one of the most common privilege escalation paths in AD environments because any domain user can request TGS tickets.

When to Use

Trigger phrases:

• "performing kerberoasting attack"

• "Kerberoasting is a post-exploitation technique that targets service accounts in "

• When conducting security assessments that involve performing kerberoasting attack

• When following incident response procedures for related security events

• When performing scheduled security testing or auditing activities

• When validating security controls through hands-on testing

Prerequisites

• Familiarity with red teaming concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

MITRE ATT&CK Mapping

• T1558.003 - Steal or Forge Kerberos Tickets: Kerberoasting
• T1087.002 - Account Discovery: Domain Account
• T1069.002 - Permission Groups Discovery: Domain Groups

Workflow

# Example: IOC detection
import re

IOC_PATTERNS = {
    "ip": r"\b(?:\d{1,3}\.){3}\d{1,3}\b",
    "domain": r"\b[a-z0-9-]+\.[a-z]{2,}\b",
    "hash_md5": r"\b[a-f0-9]{32}\b",
    "hash_sha256": r"\b[a-f0-9]{64}\b",
}

def extract_iocs(text: str) -> dict:
    return {k: re.findall(v, text) for k, v in IOC_PATTERNS.items()}

1. Scope and authorize — confirm written authorization and define target boundaries
2. Reconnaissance — enumerate targets, services, and potential attack surfaces
3. Exploitation — attempt exploitation of identified vulnerabilities within scope
4. Post-exploitation — document access level, lateral movement, and data exposure
5. Report and remediate — compile findings with reproduction steps and fix recommendations

Phase 1: SPN Enumeration

1. Enumerate accounts with SPNs using LDAP queries
2. Filter for user accounts (not computer accounts)
3. Identify accounts with elevated privileges (adminCount=1)
4. Prioritize accounts with weak password policies

Phase 2: TGS Ticket Request

1. Request TGS tickets for identified SPN accounts
2. Extract ticket data in crackable format (hashcat/john compatible)
3. Ensure RC4 encryption is requested when possible (easier to crack)
4. Document all requested tickets

Phase 3: Offline Cracking

1. Use hashcat mode 13100 (Kerberos 5 TGS-REP etype 23) for RC4 tickets
2. Use hashcat mode 19700 (Kerberos 5 TGS-REP etype 17) for AES-128
3. Use hashcat mode 19800 (Kerberos 5 TGS-REP etype 18) for AES-256
4. Apply targeted wordlists and rules based on password policy

Phase 4: Credential Validation

1. Validate cracked credentials against domain
2. Assess access level of compromised accounts
3. Map accounts to BloodHound attack paths
4. Document for engagement report

When NOT to Use

• You don't have explicit written authorization to test
• Task is about defense/detection, not offense (use detection skills)
• You need to implement security controls (use implementing-* skills)
• Task requires compliance auditing (use auditing-* skills)
• You're investigating an incident (use incident response skills)
• Target is out of scope for your engagement
• Task is about vulnerability scanning only (use scanning tools)

Red Flags

• Performing actions without explicit written authorization from the asset owner
• Testing against production systems without a defined scope and rules of engagement
• Exceeding the authorized scope of the engagement
• Leaving persistent access mechanisms without explicit approval
• Causing denial-of-service on production systems during testing

Verification

• All steps executed successfully against a test environment before production use
• Output documented with screenshots or logs demonstrating expected behavior
• All exploited vulnerabilities documented with reproduction steps
• Scope boundaries confirmed — only authorized targets were tested
• Remediation recommendations included for every finding

Tools and Resources

Detection Indicators

• Event ID 4769: Kerberos Service Ticket Request with RC4 encryption (0x17)
• Anomalous TGS requests from a single account in short timeframe
• TGS requests for services the user normally does not access
• Honeypot SPN accounts with alerting on ticket requests

Validation Criteria

• SPN accounts enumerated and documented
• TGS tickets extracted in crackable format
• Offline cracking attempted with appropriate wordlists
• Cracked credentials validated
• Access level of compromised accounts assessed

Process

1. Analyze the task requirements
2. Apply domain expertise
3. Verify output quality

Anti-Rationalization Table