Emerging applications require secure group communications around hierarchical architecture protocols, like military or public emergency applications. However, conceiving such secure hierarchical protocols is not straightforward. Thus, their verification become a primordial issue in order to avoid the possible security attacks and vulnerabilities. Several attempts have been done to deal with formal verification of group protocols, but, in our knowledge, none of them has handled hierarchical ones. This paper investigates both specific challenges and security issues of hierarchical security group communications, and an overview of works done for their verification. We have chosen the Back-end Cl-AtSe of AVISPA tool, to verify an example of such protocols, as it enables to deal with the exponentiation of Diffie-Hellman often used in group key management.