Ipswitch MOVEit DMZ before 8.2 provides different error messages for authentication attempts depending on whether the user account exists, which allows remote attackers to enumerate usernames via a series of SOAP requests to machine.aspx.
https://profundis-labs.com/advisories/CVE-2015-7680.txt
https://euvd.enisa.europa.eu/vulnerability/EUVD-2015-7582
http://seclists.org/fulldisclosure/2016/Jan/95
http://packetstormsecurity.com/files/135462/Ipswitch-MOVEit-DMZ-8.1-Information-Disclosure.html
http://docs.ipswitch.com/MOVEit/DMZ82/ReleaseNotes/MOVEitReleaseNotes82.pdf