This is a real oldie, but still worth a mention…

Java gives us a lot of persistence possibilities and one of them are environment variables; when set, they will be adhered to, and as such, can be abused:

• JAVA_HOME – where java run-time resides
• LIBRARY_PATH – where the Java libraries sit
• JVM_DLL – this is a juicy one, which Java virtual machine DLL to load

If you see these set on the system, keep an eye on what they are pointing to.