When launching the Windows Installer Version of Minecraft it downloads Java runtime 1.8.0_25 which is nearly 100 updates behind the most recent Version Java SE 8u121 offered by oracle. As such an old Version of Java may contain severe security issues and could be abused by malware as it is located under C:\Program Files (x86)\Minecraft\runtime\jre-x64 in most cases Minecraft itself is lowering the security of the Users PC