Authentication Bypass by Spoofing

Summary

When using IPAuthenticationProvider in the ZooKeeper Admin Server, there is a possibility of Authentication Bypass by spoofing; this only impacts IP-based authentication implemented in the ZooKeeper Admin Server. The default configuration of the client's IP address detection in IPAuthenticationProvider, which uses HTTP request headers, is weak and allows an attacker to bypass authentication via spoofing the client's IP address in request headers. Default configuration honors X-Forwarded-For HTTP header to read the client's IP address. The X-Forwarded-For request header is mainly used by proxy servers to identify the client and can be easily spoofed by an attacker pretending that the request comes from a different IP address. Admin server commands, such as snapshot and restore, can be executed arbitrarily on successful exploitation, which could potentially lead to information leakage or service availability issues. This issue affects the package org.apache.zookeeper:zookeeper versions 3.9.0 through 3.9.2.