chilit-nl/log4shell-exampleEl objetivo de este proyecto es demostrar la vulnerabilidad de explotación log4j cve-2021-44228 en una configuración de spring-boot, y mostrar cómo solucionarla.
El objetivo de este proyecto es demostrar la vulnerabilidad de explotación log4j cve-2021-44228 en una configuración de spring-boot, y mostrar cómo corregirla.
Este proyecto contiene tres submódulos. Uno de ellos tiene código vulnerable, los otros dos están parcheados.
Ejecuta ./mvnw clean test en la raíz del proyecto para ejecutar las pruebas en ambos módulos.
En log4shell-example-unpatched, verás muchas excepciones (la prueba seguirá pasando porque esto es lo esperado), porque no obtiene la respuesta correcta del servidor al que intenta conectarse.
Tu aplicación es vulnerable si has sobrescrito el logger por defecto, de modo que usa la implementación log4j2 y no has sobrescrito la versión de log4j2 que se utiliza. El pom se verá algo así:```xml org.springframework.boot spring-boot-starter org.springframework.boot spring-boot-starter-logging
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
Puedes comprobar que tus invocaciones de registro ahora son vulnerables ejecutando la prueba en `log4shell-example-unpatched`. Esta prueba tiene éxito cuando las invocaciones de registro son vulnerables.
### Uso de la prueba de integración de Spring para ver si tu propia aplicación es vulnerable
#### 1. Agrega el `Log4ShellTest` a tu proyecto
Agrega el `Log4ShellTest` de `log4shell-example-patched-version` a tu proyecto:```java
import lombok.extern.log4j.Log4j2;
import lombok.extern.slf4j.Slf4j;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.stereotype.Component;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
@SpringBootTest
@Import(Log4ShellTest.Log4ShellConfig.class)
public class Log4ShellTest {
@Autowired
private List<Log4ShellService> servicesToTest;
@Test
public void testVulnerabilityPatched() throws Exception {
CountDownLatch waitLatch = new CountDownLatch(1);
AtomicInteger connectionAttemptCounter = new AtomicInteger();
Thread listener = new Thread(() -> {
try {
ServerSocket socket = new ServerSocket(22345);
while(true) {
waitLatch.countDown();
Socket connection = socket.accept();
connectionAttemptCounter.getAndIncrement();
connection.close();
}
}
catch(IOException ex) {
throw new IllegalStateException(ex);
}
});
listener.start();
waitLatch.await();
servicesToTest.forEach(service -> service.testLog("${jndi:ldap://127.0.0.1:22345}"));
Assertions.assertEquals(0, connectionAttemptCounter.get());
// If you're not using lombok, change the 6 to 2
Assertions.assertEquals(6, servicesToTest.size());
listener.interrupt();
}
@Configuration
@ComponentScan
public static class Log4ShellConfig {
}
public interface Log4ShellService {
void testLog(String arg);
}
@Component
public static class Service1 implements Log4ShellService {
private static final Logger logger = LogManager.getLogger("Test");
@Override
public void testLog(String arg) {
logger.info("Test: " + arg);
}
}
@Component
public static class Service2 implements Log4ShellService {
private static final Logger logger = LogManager.getLogger("Test");
@Override
public void testLog(String arg) {
logger.info("Test: {}", arg);
}
}
// Remove this class if you're not using lombok
@Component
@Slf4j
public static class Service3 implements Log4ShellService {
@Override
public void testLog(String arg) {
log.info("Test: {}", arg);
}
}
// Remove this class if you're not using lombok
@Component
@Slf4j
public static class Service4 implements Log4ShellService {
@Override
public void testLog(String arg) {
log.info("Test: " + arg);
}
}
// Remove this class if you're not using lombok
@Component
@Log4j2
public static class Service5 implements Log4ShellService {
@Override
public void testLog(String arg) {
log.info("Test: {}", arg);
}
}
// Remove this class if you're not using lombok
@Component
@Log4j2
public static class Service6 implements Log4ShellService {
@Override
public void testLog(String arg) {
log.info("Test: " + arg);
}
}
}
Ejecuta la prueba y comprueba que falla. Si no falla, deberías ver las siguientes líneas de registro y no eres vulnerable:``` 2021-12-13 22:05:01.197 INFO 21216 --- [ main] Test : Test: ${jndi:ldap://127.0.0.1:22345} 2021-12-13 22:05:01.198 INFO 21216 --- [ main] Test : Test: ${jndi:ldap://127.0.0.1:22345} 2021-12-13 22:05:01.199 INFO 21216 --- [ main] n.c.l.Log4ShellTest$Service3 : Test: ${jndi:ldap://127.0.0.1:22345} 2021-12-13 22:05:01.199 INFO 21216 --- [ main] n.c.l.Log4ShellTest$Service4 : Test: ${jndi:ldap://127.0.0.1:22345} 2021-12-13 22:05:01.199 INFO 21216 --- [ main] n.c.l.L.Service5 : Test: ${jndi:ldap://127.0.0.1:22345} 2021-12-13 22:05:01.199 INFO 21216 --- [ main] n.c.l.L.Service6 : Test: ${jndi:ldap://127.0.0.1:22345}
Si la prueba falla, deberías ver un stack trace que dice que una conexión está cerrada:```
2021-12-13 22:06:50,635 main WARN Error looking up JNDI resource [ldap://127.0.0.1:22345]. javax.naming.CommunicationException: anonymous bind failed: 127.0.0.1:22345 [Root exception is java.net.SocketException: Socket closed]
at java.naming/com.sun.jndi.ldap.LdapClient.authenticate(LdapClient.java:198)
at java.naming/com.sun.jndi.ldap.LdapCtx.connect(LdapCtx.java:2895)
at java.naming/com.sun.jndi.ldap.LdapCtx.<init>(LdapCtx.java:348)
at java.naming/com.sun.jndi.url.ldap.ldapURLContextFactory.getUsingURLIgnoreRootDN(ldapURLContextFactory.java:60)
at java.naming/com.sun.jndi.url.ldap.ldapURLContext.getRootURLContext(ldapURLContext.java:61)
at java.naming/com.sun.jndi.toolkit.url.GenericURLContext.lookup(GenericURLContext.java:204)
at java.naming/com.sun.jndi.url.ldap.ldapURLContext.lookup(ldapURLContext.java:94)
at java.naming/javax.naming.InitialContext.lookup(InitialContext.java:409)
at org.apache.logging.log4j.core.net.JndiManager.lookup(JndiManager.java:172)
at org.apache.logging.log4j.core.lookup.JndiLookup.lookup(JndiLookup.java:56)
at org.apache.logging.log4j.core.lookup.Interpolator.lookup(Interpolator.java:221)
at org.apache.logging.log4j.core.lookup.StrSubstitutor.resolveVariable(StrSubstitutor.java:1110)
at org.apache.logging.log4j.core.lookup.StrSubstitutor.substitute(StrSubstitutor.java:1033)
at org.apache.logging.log4j.core.lookup.StrSubstitutor.substitute(StrSubstitutor.java:912)
at org.apache.logging.log4j.core.lookup.StrSubstitutor.replace(StrSubstitutor.java:467)
at org.apache.logging.log4j.core.pattern.MessagePatternConverter.format(MessagePatternConverter.java:132)
at org.apache.logging.log4j.core.pattern.PatternFormatter.format(PatternFormatter.java:38)
at org.apache.logging.log4j.core.layout.PatternLayout$PatternSerializer.toSerializable(PatternLayout.java:344)
at org.apache.logging.log4j.core.layout.PatternLayout.toText(PatternLayout.java:244)
at org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:229)
at org.apache.logging.log4j.core.layout.PatternLayout.encode(PatternLayout.java:59)
at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.directEncodeEvent(AbstractOutputStreamAppender.java:197)
at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.tryAppend(AbstractOutputStreamAppender.java:190)
at org.apache.logging.log4j.core.appender.AbstractOutputStreamAppender.append(AbstractOutputStreamAppender.java:181)
at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:156)
at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:129)
at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:120)
at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:84)
at org.apache.logging.log4j.core.config.LoggerConfig.callAppenders(LoggerConfig.java:540)
at org.apache.logging.log4j.core.config.LoggerConfig.processLogEvent(LoggerConfig.java:498)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:481)
at org.apache.logging.log4j.core.config.LoggerConfig.log(LoggerConfig.java:456)
at org.apache.logging.log4j.core.config.AwaitCompletionReliabilityStrategy.log(AwaitCompletionReliabilityStrategy.java:82)
at org.apache.logging.log4j.core.Logger.log(Logger.java:161)
at org.apache.logging.log4j.spi.AbstractLogger.tryLogMessage(AbstractLogger.java:2205)
at org.apache.logging.log4j.spi.AbstractLogger.logMessageTrackRecursion(AbstractLogger.java:2159)
at org.apache.logging.log4j.spi.AbstractLogger.logMessageSafely(AbstractLogger.java:2142)
at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2017)
at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1983)
at org.apache.logging.log4j.spi.AbstractLogger.info(AbstractLogger.java:1320)
at nl.chilit.log4shellexampleunpatched.Log4ShellTest$Service1.testLog(Log4ShellTest.java:78)
at nl.chilit.log4shellexampleunpatched.Log4ShellTest.lambda$testVulnerabilityNotPatched$1(Log4ShellTest.java:52)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at nl.chilit.log4shellexampleunpatched.Log4ShellTest.testVulnerabilityNotPatched(Log4ShellTest.java:52)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:725)
at org.junit.jupiter.engine.execution.MethodInvocation.proceed(MethodInvocation.java:60)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$ValidatingInvocation.proceed(InvocationInterceptorChain.java:131)
at org.junit.jupiter.engine.extension.TimeoutExtension.intercept(TimeoutExtension.java:149)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestableMethod(TimeoutExtension.java:140)
at org.junit.jupiter.engine.extension.TimeoutExtension.interceptTestMethod(TimeoutExtension.java:84)
at org.junit.jupiter.engine.execution.ExecutableInvoker$ReflectiveInterceptorCall.lambda$ofVoidMethod$0(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.proceed(InvocationInterceptorChain.java:64)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.chainAndInvoke(InvocationInterceptorChain.java:45)
at org.junit.jupiter.engine.execution.InvocationInterceptorChain.invoke(InvocationInterceptorChain.java:37)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:104)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:98)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$7(TestMethodTestDescriptor.java:214)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:210)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:135)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:66)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:151)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:41)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$6(NodeTestTask.java:155)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:141)
at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:137)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$9(NodeTestTask.java:139)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:138)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:95)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:35)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:107)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:88)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.lambda$execute$0(EngineExecutionOrchestrator.java:54)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.withInterceptedStreams(EngineExecutionOrchestrator.java:67)
at org.junit.platform.launcher.core.EngineExecutionOrchestrator.execute(EngineExecutionOrchestrator.java:52)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:114)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:86)
at org.junit.platform.launcher.core.DefaultLauncherSession$DelegatingLauncher.execute(DefaultLauncherSession.java:86)
at org.junit.platform.launcher.core.SessionPerRequestLauncher.execute(SessionPerRequestLauncher.java:53)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71)
at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)
at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)
Caused by: java.net.SocketException: Socket closed
at java.base/sun.nio.ch.NioSocketImpl.ensureOpenAndConnected(NioSocketImpl.java:165)
at java.base/sun.nio.ch.NioSocketImpl.beginWrite(NioSocketImpl.java:366)
at java.base/sun.nio.ch.NioSocketImpl.implWrite(NioSocketImpl.java:411)
at java.base/sun.nio.ch.NioSocketImpl.write(NioSocketImpl.java:440)
at java.base/sun.nio.ch.NioSocketImpl$2.write(NioSocketImpl.java:826)
at java.base/java.net.Socket$SocketOutputStream.write(Socket.java:1045)
at java.base/java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
at java.base/java.io.BufferedOutputStream.flush(BufferedOutputStream.java:142)
at java.naming/com.sun.jndi.ldap.Connection.writeRequest(Connection.java:414)
at java.naming/com.sun.jndi.ldap.Connection.writeRequest(Connection.java:387)
at java.naming/com.sun.jndi.ldap.LdapClient.ldapBind(LdapClient.java:359)
at java.naming/com.sun.jndi.ldap.LdapClient.authenticate(LdapClient.java:192)
... 110 more
Parchea tu aplicación de una de las formas descritas a continuación y vuelve a ejecutar la prueba. Ahora la prueba debería estar en verde.
Puedes mitigar la vulnerabilidad de varias maneras, como se demuestra en log4shell-example-patched-system-property y log4shell-example-patched-version.
Si la configuración de tu aplicación te lo permite, la mejor manera de deshacerte de la vulnerabilidad es actualizar la versión de log4j a 2.15 como mínimo.
Puedes hacerlo estableciendo log4j2.version en 2.15.0:```xml
<log4j2.version>2.15.0</log4j2.version>
Esta solución solo funciona *cuando estás usando el artefacto spring-boot-parent en algún lugar de tu cadena como padre*. Si estás utilizando `dependencyManagement` para gestionar tus dependencias de spring-boot, esta solución no te funcionará:```xml
<!-- if you are using dependency management like this, upping the version by setting log4j2.version is NOT going to work -->
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-dependencies</artifactId>
<version>2.6.1</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
NOTA: Esta corrección SOLO funciona para versiones de log4j >= 2.10
También puede mitigar el problema estableciendo la propiedad del sistema log4j2.formatMsgNoLookups en true. TENGA EN CUENTA: NO puede establecer esto en su application.properties o application.yml.
Tiene que:
-Dlog4j2.formatMsgNoLookups=true al comando de Java para iniciar el servicio)LOG4J_FORMAT_MSG_NO_LOOKUPS en true) en el entorno en el que se ejecuta la aplicaciónlog4shell-example-patched-system-property, estableciendo una propiedad del sistema incluso antes de que Spring Boot haya arrancado (antes de llamar a SpringApplication.run(...))La última solución está implementada tanto en Log4JMitigationExtension como en Log4JMitigationExtension. Dado que la prueba de integración no utiliza el método main
de Log4JMitigationExtension, se utiliza una extensión para establecer la propiedad a tiempo para que log4j pueda detectarla.