From help desk impersonation to AD CS abuse: Investigating ESC1 and ESC8 intrusion paths
Source Microsoft Security Blog
Description
Microsoft Threat Intelligence analyzed two human-operated intrusion cases where attackers used Microsoft Teams to impersonate IT support and socially engineer users into granting remote access via Quick Assist. The attackers then staged portable runtimes, performed host and network discovery, and abused Active Directory Certificate Services (AD CS) to obtain authentication certificates for privileged accounts. Two distinct AD CS abuse techniques were observed: ESC1 template abuse allowing certificate issuance for privileged accounts, and ESC8 NTLM relay to AD CS Web Enrollment to obtain domain-controller certificates. These certificate-based authentications enabled persistent privileged access independent of passwords. The incidents highlight risks from social engineering combined with insecure or overly permissive AD CS configurations rather than software vulnerabilities. Microsoft Defender detections and containment effectiveness varied between cases, influencing the extent of attacker progression.