A clever spam campaign is underway that pretends to be a WebEx meeting invite and uses a Cisco open redirect that pushes a Remote Access Trojan to the recipient. An open redirect is when a legitimate site allows unauthorized users to create URLs on that site to redirect visitors to other sites that they wish. This allows an attacker to utilize the URL of a well-known and respected company to deliver malware or phishing campaigns. Using these types of URLs, attackers can more easily trick victims into clicking on them.
Source: https://www.bleepingcomputer.com/news/security/clever-webex-spam-use-cisco-redirect-to-deliver-rat-malware/