It looks like #WannaCry’s killswitch check (www[.]iuqerfsodp9ifjaposdfjhgosurijfaewrwergwea[.]com) is not proxy aware:
Organizations that use proxies will not benefit from the killswitch.
Sample: 5ad4efd90dcde01d26cc6f32f7ce3ce0b4d4951d4b94a19aa097341aff2acaec
I have not tested this in a VM. If someone has, please post a comment with your findings.
Article Link: https://blog.didierstevens.com/2017/05/13/quickpost-wcry-killswitch-check-is-not-proxy-aware/