Listed below are mirror patch download for update to PREVENT wannacrypt ransomware. It seems Microsoft server got really busy right now.
- Windows XP: https://tonggoes.ga/repo/wannacrypt_patch/WindowsXP-KB4012598-x86-Embedded-Custom-ENU.exe
- Windows 8: https://tonggoes.ga/repo/wannacrypt_patch/Windows8-RT-KB4012598-x64-custom.msu
Note: Those patch seems to be effective for prevention methods only. If you has already infected, then those patch might not help much but at least will decrease the infection rate furthermore.