Hackers use two methods of delivering malicious code through IM : delivery of virus , trojan , or spyware within an infected file , and the use of `` socially engineered '' text with a web address that entices the recipient to click on a URL that connects him or her to a website that then downloads malicious code . Hackers use two methods of delivering malicious code through IM : delivery of viruses , trojan horses , or spyware within an infected file , and the use of `` socially engineered '' text with a web address that entices the recipient to click on a URL connecting him or her to a website that then downloads malicious code .