The winbox service in MikroTik RouterOS 5.15 and earlier allows remote attackers to cause a denial of service (CPU consumption), read the router version, and possibly have other impacts via a request to download the router's DLLs or plugins, as demonstrated by roteros.dll.
https://exchange.xforce.ibmcloud.com/vulnerabilities/75327
https://euvd.enisa.europa.eu/vulnerability/EUVD-2012-5924
http://www.exploit-db.com/exploits/18817
http://www.133tsec.com/2012/04/30/0day-ddos-mikrotik-server-side-ddos-attack/