Which of the following application attacks is used against a corporate directory service where there are unknown servers on the network?

A rogue access point is a wireless attack placing an unauthorized AP on the network, not an attack against a directory service.

A zero-day attack exploits an unknown software vulnerability, not a technique for querying or manipulating a directory service.

Packet sniffing is a passive eavesdropping technique used to capture network traffic, not an attack against a directory service application.

LDAP injection exploits vulnerable directory service queries by inserting unsanitized input into LDAP statements, allowing an attacker to enumerate or manipulate directory objects such as users, groups, and unknown servers. Because corporate directory services like Active Directory use LDAP, this attack directly targets the service described. The presence of unknown servers suggests the attacker used injected queries to discover hidden directory objects.