This indicates an attack attempt to exploit a Directory Traversal vulnerability in Zimbra Collaboration Server.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling crafted HTTP requests. A remote attacker can exploit this to gain unauthorized access to sensitive information via a crafted HTTP request. Also, remote attacker can gain administration privileges, gain access to Administration Console, and upload arbitrary files with custom content to vulnerable server, leading to remote code execution.
Zimbra Collaboration Server 7.2.2
Zimbra Collaboration Server 8.0.2
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
System Compromise: Remote attackers can gain control of vulnerable systems.
Privilege Escalation: Remote attackers can leverage their privilege on the vulnerable systems.
Apply the most recent upgrade or patch from the vendor.
Note: This signature requires "SSL Inspection" in FortiOS 5.0 and above to detect the attack.