cve.2026-54121 on Detection.FYI

ADCS - Certighost CDC Chase Certificate Request (CVE-2026-54121)

Wed, 05 Aug 2026 08:52:16 +0000

Detects Active Directory Certificate Services (ADCS) certificate requests that include the 'cdc' (Client DC) request attribute pointing to a domain or IP that is not a known Domain Controller. 'cdc' is an optional MS-WCCE enrollment attribute designed for cross-domain/cross-forest scenarios where a client in a child domain tells the CA which DC to contact for identity lookups when the CA cannot reach that domain directly. Legitimate values are DC hostnames or IPs that resolve to a real Domain Controller computer object in AD with the SERVER_TRUST_ACCOUNT (0x2000) userAccountControl bit set. In an attack, the attacker sets cdc to a domain or IP they control so the CA connects to their rogue SMB and LDAP services instead of a real DC. The rogue server returns a forged DC identity which the pre-patch CA accepts without validation. A malicious event looks like: Requester: DOMAIN\GHOST$ Attributes: cdc: rmd: SubjectAlternativeName: DNS Name= CVE-2026-54121 (Certighost) is the known exploit for this path. The July 2026 patch added _ValidateChaseTargetIsDC which rejects cdc values that do not resolve to a legitimate DC object in Active Directory before following the chase.

ADCS - Certighost Certificate Issued via CDC Chase (CVE-2026-54121)

Wed, 05 Aug 2026 08:52:16 +0000

Detects successful issuance of an ADCS certificate where the request attributes include 'cdc' (Client DC) or 'rmd' (Remote Domain) pointing to a non-DC domain or IP, confirming the CA's chase fallback path was taken against an attacker-controlled target. 'cdc' directs the CA to an address for identity lookup; 'rmd' specifies the principal to look up there. In an attack (CVE-2026-54121, Certighost), cdc points to a rogue host that returns a forged DC identity. A successfully issued certificate at this stage means the attacker has obtained a cert carrying a Domain Controller's SID and DNS identity, enabling PKINIT authentication as that DC followed by DCSync replication.

ADCS - Certighost Ghost Machine Account Creation

Wed, 05 Aug 2026 08:52:16 +0000

Detects the creation of a machine account whose name starts with 'GHOST', which is the naming convention used by the CVE-2026-54121 (Certighost) exploit tooling. The public proof-of-concept for Certighost creates a temporary machine account with a name of the form GHOST$ before enrolling for a DC certificate via the cdc chase path. The attacker-controlled machine account is used as the requester identity in the certificate request; the cdc attribute then redirects the CA to a rogue host that returns a forged Domain Controller identity. The resulting certificate carries the DC's SID and DNS name, enabling full PKINIT authentication as the targeted DC followed by DCSync. A machine account creation event (4741) where TargetUserName starts with 'GHOST' and ends with '$' is a high-fidelity indicator of this attack tool's execution. Legitimate environments very rarely provision machine accounts with this prefix.

Suspicious Machine Account Replication - DcSync Indicator

Wed, 05 Aug 2026 08:52:16 +0000

Detects suspicious Active Directory Replication Service (ADRS) requests originating from a machine account (SubjectUserName ending in '$') rather than a legitimate Domain Controller. Under normal operation, only Domain Controllers initiate replication requests carrying the DS-Replication-Get-Changes-All right. If a threat actor obtains valid machine account credentials — for example by abusing certificate-based authentication (PKINIT) to impersonate a DC after exploiting a CA vulnerability such as CVE-2026-54121 (Certighost), where a temporary machine account is created to request a DC certificate and then used to perform DCSync — they can dump all domain credential material including the krbtgt hash.