• Posted by: Eng. Donya Bino
• December 08, 2025

Shadow Credentials Attacks: How Hackers Slip Into AD Without Passwords

A Shadow Credentials attack is basically an attacker creating a hidden authentication method for themselves inside your Active Directory environment.
Instead of stealing a user’s password, they add a new key, certificate, or authentication artifact behind the scenes.
Think of it like someone quietly making a spare key to your house, not by stealing your original key, but by messing with the lock when you’re not looking.
Once that’s done?
They can come and go as they please.

How Attackers Pull This Off
There are a few common ways attackers create these "ghost credentials":
Abusing ADCS (Active Directory Certificate Services)
Attackers can, in such cases:
1. Request certificates that they shouldn’t have access to
2. Create fake certificate mappings for privileged accounts
3. Authenticate users, without using the password
It's basically identity fraud, but for machines.

Changing msDS-KeyCredentialLink
This is the big one.
Attackers can add a malicious public key to the msDS-KeyCredentialLink attribute of a domain account.
That means they can authenticate using Pass-the-Key or PKINIT-based attacks, no password needed.

It’s as sneaky as it sounds:
1. No password reset notifications
2. No MFA prompt
3. No one gets alerted
4. And everything looks “legitimate”

Abusing Kerberos and FIDO2 Mechanisms
Since these newer authentication methods rely on key pairs, attackers simply slide in their own key, like a silent partner in a bad business deal.

Why Shadow Credentials Are So Dangerous
Because once they’re in, they don’t need to steal credentials anymore.
They become the credentials.
A successful Shadow Credentials attack gives the attacker:
1. Persistent access
2. Password-less authentication
3. MFA bypass
4. Domain-wide lateral movement

How You Actually Catch This Stuff
Shadow Credentials are subtle, but not invisible, if you’re looking in the right places.
Review msDS-KeyCredentialLink regularly
Any unexpected keys = red flag.

Monitor certificate enrollments
Especially when a non-privileged account starts acting “ambitious.”

Audit ADCS templates
And fix the misconfigurations attackers love:
1. Enrollment rights
2. EKU misuse
3. Subject Name misconfigurations

Alert on unusual authentication behavior
Like accounts authenticating without password failures or MFA interactions.

Use threat intelligence to spot TTPs
Shadow Credentials are a favorite technique in:
1. APT intrusions
2. Long-term espionage
3. Privilege escalation chains
If they show up, someone highly motivated is probably in your network.

How to Protect Your Organization 
1. Harden ADCS
This solves half the problem immediately.
2. Least privilege actually matters here
Don’t give certificate enrollment to random accounts “just because.”
3. Rotate keys and enforce certificate lifetimes
Long-lived certificates = long-lived attackers.
4. Use EDR with identity-focused visibility
Modern attacks are identity attacks. Your tools need to see identity abuse clearly.
5. Run regular AD health checks
If you don’t review your identity environment, attackers will do it for you.

You can’t protect your network if you treat identity security like a “set it and forget it” job. Attackers certainly don’t.