LDAP StartTLS Man-in-the-Middle Certificate Impersonation

This vulnerability affects User Account and Authentication (UAA) deployments that rely on LDAP authentication over StartTLS, a protocol used to encrypt LDAP communications. An attacker positioned on the network between UAA and its LDAP directory can intercept the connection and impersonate the LDAP server using any certificate issued by a trusted Certificate Authority. Once the attacker establishes this man-in-the-middle position, they can harvest LDAP bind passwords and every end-user password transmitted during simple-bind authentication. More critically, the attacker can return forged group memberships that grant themselves administrative scopes, effectively elevating their privileges to administrator level. This affects all UAA deployments prior to v78.13.0 and Cloud Foundry deployments prior to v56.2.0 that authenticate users against LDAP over StartTLS—a common authentication pattern in enterprise environments.

Casky's platform, powered by Claude AI with extended reasoning capabilities, would detect attack patterns associated with this vulnerability by correlating indicators across credential access and privilege escalation techniques. Practitioners using Casky would observe findings related to T1187 (Forced Authentication), which describes the credential harvesting aspect of this attack, and T1556 (Modify Authentication Process), which covers the forged group membership injection that grants unauthorized administrative access. Additionally, the findings would flag T1021 (Remote Services) for the network positioning required, and T1556.002 specifically for LDAP modifications. When analyzing suspicious LDAP authentication logs, Casky would highlight patterns of certificate mismatches, unexpected group membership changes, or authentication attempts from unusual network positions—enabling practitioners to identify active exploitation before credentials are compromised or privilege escalation occurs.