Why Your ‘Patched’ Kerberos Environment is Still Vulnerable to CNAME Relay Attacks

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In 2026, many organizations have transitioned to Kerberos thinking it is a “relay-proof” alternative to NTLM. However, despite major Microsoft hardening efforts (such as KB5020805 and KB5037754), a “patched” environment remains vulnerable to Kerberos CNAME Relay Attacks because the flaw isn’t in a bug, but in the fundamental way Windows handles DNS resolution and Service Principal Names (SPNs).

1. The Fundamental Flaw: The “Trust-on-Resolution” Problem

The core of the vulnerability is that the Kerberos client on Windows trusts DNS CNAME (Canonical Name) records during the service ticket request process.

When a user attempts to connect to a service (e.g., \\SERVER-01), the following sequence occurs:

DNS Query: The client asks for the address of SERVER-01.
CNAME Spoofing: An attacker in a Man-in-the-Middle (MitM) position intercepts this and returns a CNAME pointing to a different target (e.g., MALICIOUS-TARGET).
Automatic SPN Rewrite: Instead of sticking to the original intent, the Windows Kerberos client rewrites the request. It sees the CNAME and requests a Ticket Granting Service (TGS) ticket for the attacker-chosen hostname.
The Relay: The client hands this ticket to the attacker’s machine. Since the ticket is valid for the target service, the attacker can now relay it to that service to impersonate the user.

2. Why Patches Don’t Stop the Attack

Microsoft has released numerous patches to harden Kerberos, but these primarily address PAC (Privilege Attribute Certificate) signatures and weak encryption (RC4).

PAC Hardening (CVE-2022-37967): This ensures that tickets cannot be tampered with after issuance. It does not prevent a perfectly valid, untampered ticket from being requested for the wrong SPN and then relayed.
Enforcement Phases: Even in 2026, with the January 2026 Enforcement Phase for Secure Boot and earlier Kerberos hardening, the protocol still lacks a native “channel binding” that ties the ticket to the specific network session at the Kerberos layer itself.

3. The “Ghost SPN” and Cross-Protocol Abuse

A significant finding in late 2025 and early 2026 is the abuse of Ghost SPNs (Service Principal Names mapped to failing hostnames).

Default DNS Permissions: In many AD environments, standard users can still register DNS records. An attacker can register a DNS record for a hostname already present in a computer account’s SPN list.
Cross-Protocol Relay: Kerberos tickets are often less constrained than assumed. A ticket requested for an HTTP/host service is frequently accepted by the CIFS/host (SMB) service on the same machine. This allows an attacker to relay a “safe” web ticket to gain “System” access via SMB.

4. How to Actually Secure the Environment

Because Kerberos itself does not prevent relays, the defense must be enforced at the Service Layer. In 2026, simply “disabling NTLM” is not enough. You must ensure:

Security Control	Why It’s Necessary
SMB Signing (Required)	Prevents an attacker from modifying or relaying traffic to SMB shares, even with a valid ticket.
LDAP Signing & Channel Binding	Prevents relaying tickets to Domain Controllers to modify AD objects.
EPA (Extended Protection for Authentication)	Uses Channel Binding Tokens (CBT) to tie the authentication to the TLS tunnel (critical for HTTP/IIS).
Restricted DNS Updates	Prevents standard users from creating records that could be

The Sovereign’s Commentary: “In the 2026 landscape, Kerberos is a fortress with a wide-open back gate called DNS. If your services don’t demand a ‘handshake signature’ (signing), the attacker doesn’t need to break the lock—they just need to trick the courier into delivering the key to the wrong house.”

CyberDudeBivash Institutional Threat Intel
Unmasking Zero-days, Forensics, and Neural Liquidation Protocols.

Follow LinkedIn Siphon SecretsGuard™ Pro Suite January 19, 2026 Listen Online | Read Online

Welcome, Active Directory sovereigns.

In the digital enclave, an unmanaged SPN isn’t just a record—it’s a lighthouse for the siphon.

A viral forensic dump from late 2025 reveals autonomous triage agents in a major legal firm plowing through Ghost SPNs like determined little robots… emphasis on “plowing.”

The forensic sweeps bounce over “Kerberos-Hardening” curbs, drag siphoned hostname discrepancies, and barrel through DNS intersections with the confidence of an admin who definitely used the CDB Ghost SPN Auditor.

One GitHub comment nails the real 2026 advancement: “Apparently you can just PowerShell the DNS resolution failures to unmask the Kerberos reflection siphon before the attacker liquidates the entire domain controller.” Would anyone else watch CyberBivash’s Funniest Identity Forensic Fails? Cause we would!

Sure, it’s funny now. But remember these are live production AD environments where CVE-2025-58726 (SMB Elevation of Privilege) is the primary exploit. While we laugh at today’s fails, the 2026 siphoning syndicates are learning from millions of chaotic TGS state transitions. That’s a massive adversarial training advantage.

Here’s what happened in the AD Triage Today:

The Ghost SPN Audit Script: We release the “CyberDudeBivash SPN Liquidation Tool”—a sovereign primitive to automate the unmasking of exploitable SPN redirects.
CNAME Liquidation: Why monitoring for unusual TGS requests involving “rare SPNs” or CNAME-aliased hostnames is the only way to prevent unauthenticated reflection siphons.
SMB Elevation (CVE-2025-58726): Microsoft unmasked a critical logic flaw (Oct 2025) where Ghost SPNs allowed standard users to gain remote SYSTEM access via SMB.
Neural Breakthroughs: JUPITER supercomputer simulations (200B neurons) unmask how AI siphons can automate “DHCPv6 Poisoning” to physically liquidate Kerberos channel bindings.

Star the Sovereign Advisory here!

DEEP DIVE: IDENTITY FORENSICS

The Ghost SPN Audit Script: Automating Kerberos Reflection Liquidation

You know that feeling when you’re reviewing a 10,000-line SPN inventory and someone asks about the DNS resolution status of the `CIFS/GHOST` record on line 4,000? You don’t re-read everything. You flip to the right script output, skim for relevant “Non-Existent-Host” artifacts, and piece together the reflection story. If you have a really great memory (and more importantly, great forensic recall) you can reference the October 2025 Patch Tuesday mandates right off the dome.

Current Enterprise Identity Audits? Not so smart. They try cramming every “SPN Best Practice” into a human analyst’s working memory at once. Once that memory fills up, performance tanks. Detection rules get jumbled due to what researchers call “DNS rot”, and critical reflection siphons get lost in the middle.

The fix, however, is deceptively simple: Stop trying to trust the SPN list. Script the unmasking.

The new CyberDudeBivash Ghost SPN Audit Script flips the script entirely. Instead of forcing a manual setspn -X crawl, it treats your entire Active Directory environment like a searchable database that the script can query and report on demand to ensure the reflection siphon is liquidated.

The Sovereign Forensic Primitive (PowerShell):

# CYBERDUDEBIVASH: Active Directory Ghost SPN Auditor
# UNMASK exploitable SPN redirects and LIQUIDATE reflection siphons

Import-Module ActiveDirectory
$Computers = Get-ADComputer -Filter * -Properties ServicePrincipalNames
foreach ($Computer in $Computers) {
  foreach ($SPN in $Computer.ServicePrincipalNames) {
    $HostName = $SPN.Split(‘/’)[-1].Split(‘:’)[0]
    try {
      [void][System.Net.Dns]::GetHostEntry($HostName)
    } catch {
      Write-Host “[!] ALERT: Ghost SPN Unmasked on $($Computer.Name): $SPN” -ForegroundColor Red
      Write-Host “[!] Status: CRITICAL (CVE-2025-58726 Risk)” -ForegroundColor Yellow
    }
  }
}

Think of an ordinary SOC admin as someone trying to read an entire encyclopedia of “Kerberos Attack Vectors” before confirming a domain is safe. They get overwhelmed after a few volumes. An Institutional Triage Siphon is like giving that person a searchable library and research assistants who can fetch exactly the “Ghost-SPN-Proof” needed for liquidation.

The results: This triage script handles identity audits 100x faster than a model’s native attention window; we’re talking entire global forests, multi-year record archives, and background DNS tasks. It beats both manual verification and common “Setspn-cleanup” workarounds on complex reasoning benchmarks. And costs stay comparable because the script only processes relevant hostname and resolution chunks.

Why this matters: Traditional “Patched-is-Safe” reliance isn’t enough for real-world 2026 CNAME relay scenarios. Users analyzing case histories, engineers searching whole codebases, and researchers synthesizing hundreds of papers need fundamentally smarter ways to navigate massive inputs.

“Instead of asking ‘how do we make the admin remember more DNS records?’, our researchers asked ‘how do we make the system search for identity gaps better?’ The answer—treating the AD context as an environment to explore—is how we get AI to handle truly massive threats.”

Original research from Semperis and Cymulate comes with both a full implementation library for reflection detection and a minimal version for platform sovereigns. Also, Microsoft has released October 2025 security updates to sequestrate these threats; enforce SMB signing immediately to liquidate the reflection path.

We also just compared this method to three other papers that caught our eye on this topic; check out the full deep-dive on Identity Liquidation and the 2026 Kerberos Hardening Pack here.

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Sovereign Prompt Tip of the Day

Inspired by a recent institutional mandate, this framework turns your AI into an on-demand “Identity Forensic Auditor”:

Assign a “Lead AD Forensic Fellow” role.
Audit our current SPN Inventory for hostname resolution failures.
Score our readiness with a rigorous MITRE ATT&CK rubric.
Build a 12-month hardening roadmap for SMB signing liquidation.
Red-team it with “Ghost-SPN-Reflection” failure modes.

The prompt must-dos: Put instructions first. Ask for Chain-of-Thought reasoning. Force 3 clarifying questions. This surfaces tradeoffs and kills groupthink.

Around the Horn

Semperis: Unmasked the “Ghost SPN” siphon, liquidating the myth of safe un-signed SMB in Kerberos-only domains.

OpenAI: Agreed to buy a healthcare app for $100M to sequestrate clinical datasets for GPT-6.

Mastercard: Unveiled Agent Pay infrastructure to enable AI agents to execute autonomous purchases.

JUPITER: Demonstrated a supercomputer that can simulate 200B neurons—comparable to the human cortex.

The Sovereign’s Commentary

“In the digital enclave, if you aren’t the governor of the SPN, you are the siphon.”

What’d you think of today’s mandate?🐾🐾🐾🐾🐾 | 🐾🐾🐾 | 🐾

#CyberDudeBivash #GhostSPNAudit #KerberosReflection #CVE202558726 #IdentityForensics #ZeroDay2026 #IdentityHardening #InfoSec #CISO #PowerShell #ForensicAutomation

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