Detecting Dcsync Attack In Active Directory

What it does

When your agent uses it

• Hunting for credential theft via Mimikatz lsadump::dcsync
• Impacket secretsdump
• Investigating lateral movement with domain admin credentials
• Auditing AD replication permissions

Example prompts

• “/detecting-dcsync-attack-in-active-directory”

Requirements

• Python 3

Workflow steps

7 steps, taken from the first numbered list in SKILL.md.

1. 1Identify Legitimate Replication Sources: Document all domain controllers in the environment by hostname, IP, and computer account. Only…
2. 2Enable Required Auditing: Configure Advanced Audit Policy to capture Event ID 4662 on domain controllers with specific GUID monitoring for…
3. 3Monitor Replication Rights Access: Track access to three critical GUIDs -- DS-Replication-Get-Changes…
4. 4Detect Non-DC Replication Requests: Alert when any account NOT associated with a domain controller requests replication rights.
5. 5Correlate with Network Traffic: DCSync generates replication traffic (MS-DRSR/RPC) from the attacker's machine to the DC. Monitor for…
6. 6Investigate Source Context: Examine the process, user account, and machine originating the replication request.
7. 7Check for Credential Abuse: After DCSync detection, audit for subsequent use of extracted hashes (pass-the-hash, golden ticket creation).

What it can do on your machine

Read from SKILL.md and the folder at commit 54a7988. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 2 files in scripts/ (Python), which the agent can run.

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Detecting Dcsync Attack In Active Directory loads about 1.7k tokens when it runs, and up to ~3.6k if it reads all its reference files. Until then it costs about 129 tokens; SKILL.md has 451 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~129

When it runs · the whole SKILL.md, loaded when a task matches

~1.7k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~3.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from mukul975/Anthropic-Cybersecurity-Skills at commit 54a7988, republished under its Apache-2.0 licence (© mukul975). 451 words, ~1,693 tokens.

name

detecting-dcsync-attack-in-active-directory

description

Detect DCSync attacks (MITRE T1003.006) where adversaries abuse Active Directory replication privileges to extract password hashes, by auditing Event ID 4662 for the DS-Replication-Get-Changes GUIDs and flagging non-domain-controller accounts issuing DsGetNCChanges RPC calls. Use when hunting for credential theft via Mimikatz lsadump::dcsync or Impacket secretsdump, investigating lateral movement with domain admin credentials, or auditing AD replication permissions.

domain

cybersecurity

subdomain

threat-hunting

tags

threat-hunting, active-directory, dcsync, credential-theft, mitre-t1003-006, mimikatz, kerberos

version

1.0

author

mahipal

license

Apache-2.0

d3fend_techniques

Application Protocol Command Analysis, Network Isolation, Network Traffic Analysis, Client-server Payload Profiling, Platform Monitoring

nist_csf

DE.CM-01, DE.AE-02, DE.AE-07, ID.RA-05

mitre_attack

T1046, T1057, T1082, T1083, T1003

index=wineventlog EventCode=4662
| where Properties IN ("*1131f6aa-9c07-11d1-f79f-00c04fc2dcd2*",
    "*1131f6ad-9c07-11d1-f79f-00c04fc2dcd2*",
    "*89e95b76-444d-4c62-991a-0facbeda640c*")
| where NOT match(SubjectUserName, ".*\\$$")
| where NOT SubjectUserName IN ("known_svc_account1", "known_svc_account2")
| stats count values(Properties) as ReplicationRights by SubjectUserName SubjectDomainName Computer
| where count > 0
| table SubjectUserName SubjectDomainName Computer count ReplicationRights

SecurityEvent
| where EventID == 4662
| where Properties has "1131f6ad-9c07-11d1-f79f-00c04fc2dcd2"
    or Properties has "1131f6aa-9c07-11d1-f79f-00c04fc2dcd2"
| where SubjectUserName !endswith "$"
| where SubjectUserName !in ("AzureADConnect", "MSOL_*")
| project TimeGenerated, SubjectUserName, SubjectDomainName, Computer, Properties
| sort by TimeGenerated desc

title: DCSync Activity Detected - Non-DC Replication Request
status: stable
logsource:
    product: windows
    service: security
detection:
    selection:
        EventID: 4662
        Properties|contains:
            - '1131f6aa-9c07-11d1-f79f-00c04fc2dcd2'
            - '1131f6ad-9c07-11d1-f79f-00c04fc2dcd2'
    filter_dc:
        SubjectUserName|endswith: '$'
    condition: selection and not filter_dc
level: critical
tags:
    - attack.credential_access
    - attack.t1003.006

Hunt ID: TH-DCSYNC-[DATE]-[SEQ]
Alert Severity: Critical
Source Account: [Account requesting replication]
Source Machine: [Hostname/IP of requestor]
Target DC: [Domain controller receiving request]
Replication Rights: [GUIDs accessed]
Timestamp: [Event time]
Legitimate DC: [Yes/No]
Known Service Account: [Yes/No]
Risk Assessment: [Critical - non-DC replication detected]

© mukul975, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 7 other files (scripts, references, assets) in skills/detecting-dcsync-attack-in-active-directory of mukul975/Anthropic-Cybersecurity-Skills.

• SKILL.md
• LICENSE
• assets/template.md
• references/api-reference.md
• references/standards.md
• references/workflows.md
• scripts/agent.py
• scripts/process.py

Open the folder on GitHubat commit 54a7988