It looks like #WannaCrys killswitch check (www[.]iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com) is not proxy aware. In an environment with an HTTP proxy and no direct connections to the Internet, the sample can not connect to www.uqerfjapoorsh.com, and it will infect the host. If I patch the sample to make it proxy aware, it can connect to the site through the proxy.”]
Source: https://blog.didierstevens.com/2017/05/13/quickpost-wcry-killswitch-check-is-not-proxy-aware/