What it does. Detect dangerous ACL misconfigurations in Active Directory using ldap3 Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill analyzing-active-directory-acl-abuse, or copy the skill folder into ~/.claude/skills/analyzing-active-directory-acl-abuse/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/analyzing-active-directory-acl-abuse/SKILL.md

SKILL.md (verbatim)

name: analyzing-active-directory-acl-abuse
description: Detect dangerous ACL misconfigurations in Active Directory using ldap3
  to identify GenericAll, WriteDACL, and WriteOwner abuse paths
domain: cybersecurity
subdomain: identity-security
tags:
- active-directory
- acl-abuse
- ldap
- privilege-escalation
version: '1.0'
author: mahipal
license: Apache-2.0
nist_csf:
- PR.AA-01
- PR.AA-05
- PR.AA-06
mitre_attack:
- T1098
- T1098.007
- T1484.001
- T1222.001
- T1078.002

Analyzing Active Directory ACL Abuse

Overview

Active Directory Access Control Lists (ACLs) define permissions on AD objects through Discretionary Access Control Lists (DACLs) containing Access Control Entries (ACEs). Misconfigured ACEs can grant non-privileged users dangerous permissions such as GenericAll (full control), WriteDACL (modify permissions), WriteOwner (take ownership), and GenericWrite (modify attributes) on sensitive objects like Domain Admins groups, domain controllers, or GPOs.

This skill uses the ldap3 Python library to connect to a Domain Controller, query objects with their nTSecurityDescriptor attribute, parse the binary security descriptor into SDDL (Security Descriptor Definition Language) format, and identify ACEs that grant dangerous permissions to non-administrative principals. These misconfigurations are the basis for ACL-based attack paths discovered by tools like BloodHound.

When to Use

• When investigating security incidents that require analyzing active directory acl abuse
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Python 3.9 or later with ldap3 library (pip install ldap3)
• Domain user credentials with read access to AD objects
• Network connectivity to Domain Controller on port 389 (LDAP) or 636 (LDAPS)
• Understanding of Active Directory security model and SDDL format

Steps

1. Connect to Domain Controller: Establish an LDAP connection using ldap3 with NTLM or simple authentication. Use LDAPS (port 636) for encrypted connections in production.

2. Query target objects: Search the target OU or entire domain for objects including users, groups, computers, and OUs. Request the nTSecurityDescriptor, distinguishedName, objectClass, and sAMAccountName attributes.

3. Parse security descriptors: Convert the binary nTSecurityDescriptor into its SDDL string representation. Parse each ACE in the DACL to extract the trustee SID, access mask, and ACE type (allow/deny).

4. Resolve SIDs to principals: Map security identifiers (SIDs) to human-readable account names using LDAP lookups against the domain. Identify well-known SIDs for built-in groups.

5. Check for dangerous permissions: Compare each ACE's access mask against dangerous permission bitmasks: GenericAll (0x10000000), WriteDACL (0x00040000), WriteOwner (0x00080000), GenericWrite (0x40000000), and WriteProperty for specific extended rights.

6. Filter non-admin trustees: Exclude expected administrative trustees (Domain Admins, Enterprise Admins, SYSTEM, Administrators) and flag ACEs where non-privileged users or groups hold dangerous permissions.

7. Map attack paths: For each finding, document the potential attack chain (e.g., GenericAll on user allows password reset, WriteDACL on group allows adding self to group).

8. Generate remediation report: Output a JSON report with all dangerous ACEs, affected objects, non-admin trustees, and recommended remediation steps.

Expected Output

{
  "domain": "corp.example.com",
  "objects_scanned": 1247,
  "dangerous_aces_found": 8,
  "findings": [
    {
      "severity": "critical",
      "target_object": "CN=Domain Admins,CN=Users,DC=corp,DC=example,DC=com",
      "target_type": "group",
      "trustee": "CORP\\helpdesk-team",
      "permission": "GenericAll",
      "access_mask": "0x10000000",
      "ace_type": "ACCESS_ALLOWED",
      "attack_path": "GenericAll on Domain Admins group allows adding arbitrary members",
      "remediation": "Remove GenericAll ACE for helpdesk-team on Domain Admins"
    }
  ]
}

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

Active Directory ACL Abuse API Reference

ldap3 Python Connection

from ldap3 import Server, Connection, ALL, NTLM, SUBTREE

server = Server("192.168.1.10", get_info=ALL, use_ssl=False)
conn = Connection(server, user="DOMAIN\\user", password="pass",
                  authentication=NTLM, auto_bind=True)

# Search with nTSecurityDescriptor
conn.search(
    "DC=corp,DC=example,DC=com",
    "(objectClass=group)",
    search_scope=SUBTREE,
    attributes=["distinguishedName", "sAMAccountName",
                "objectClass", "nTSecurityDescriptor"],
)

SDDL ACE Format

ACE String: (ace_type;ace_flags;rights;object_guid;inherit_guid;trustee_sid)
Example:    (A;;GA;;;S-1-5-21-xxx-512)

Dangerous Permission Bitmasks

BloodHound Cypher Queries for ACL Paths

-- Find all users with GenericAll on Domain Admins
MATCH p=(n:User)-[r:GenericAll]->(g:Group {name:"DOMAIN ADMINS@CORP.COM"})
RETURN p

-- Find WriteDACL paths from non-admins to high-value targets
MATCH (n:User {admincount:false})
MATCH p=allShortestPaths((n)-[r:WriteDacl|WriteOwner|GenericAll*1..]->(m:Group))
WHERE m.highvalue = true
RETURN p

-- Find GenericWrite on computers for RBCD attacks
MATCH p=(n:User)-[r:GenericWrite]->(c:Computer)
WHERE NOT n.admincount
RETURN n.name, c.name

-- Enumerate all outbound ACL edges for a principal
MATCH p=(n {name:"HELPDESK@CORP.COM"})-[r:GenericAll|GenericWrite|WriteDacl|WriteOwner|Owns]->(m)
RETURN type(r), m.name, labels(m)

-- Find shortest ACL abuse path to Domain Admin
MATCH (n:User {name:"JSMITH@CORP.COM"})
MATCH (da:Group {name:"DOMAIN ADMINS@CORP.COM"})
MATCH p=shortestPath((n)-[r:MemberOf|GenericAll|GenericWrite|WriteDacl|WriteOwner|Owns|ForceChangePassword*1..]->(da))
RETURN p

PowerView Commands for ACL Enumeration

# Get ACL for Domain Admins group
Get-DomainObjectAcl -Identity "Domain Admins" -ResolveGUIDs

# Find interesting ACEs for non-admin users
Find-InterestingDomainAcl -ResolveGUIDs | Where-Object {
    $_.ActiveDirectoryRights -match "GenericAll|WriteDacl|WriteOwner"
}

# Get ACL for specific OU
Get-DomainObjectAcl -SearchBase "OU=Servers,DC=corp,DC=com" -ResolveGUIDs

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