Log4j 2 rc1 executes unsigned content by checking for plugins

Hey guys,

In our laboratory infrastructure we launch java applications as java webstarts. These applications have to be signed.
This now leads us to the following problem:
Log4j2 rc1 seems to check for plugins in the java home directory of the operating system and tries to access/execute some code of the contained jar files. These files are not signed.
These cicumstances lead to a Security Exception which did not occur in all minor Log4j2 versions (including beta 9).

Let me give you some more details.

Here is the stacktrace showing the situation before the program crashes:

"javawsApplicationMain" prio=5 tid=1131a1800 nid=0x13fab6000 in Object.wait()
[13fab2000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)

• waiting on <7f47700a0> (a java.lang.Object)
  at java.lang.Object.wait(Object.java:485)
  at
  com.sun.javaws.ui.JavawsSysRun.delegate(JavawsSysRun.java:214)
• locked <7f47700a0> (a java.lang.Object)
  at
  com.sun.deploy.util.DeploySysRun.execute(DeploySysRun.java:24)
  at
  com.sun.deploy.util.DeploySysRun$1.run(DeploySysRun.java:46)
  at
  java.security.AccessController.doPrivileged(Native
  Method)
  at
  com.sun.deploy.util.DeploySysRun.executePrivileged(DeploySysRun.java:42)
  at
  com.sun.deploy.ui.UIFactory.showMixedCodeDialog(UIFactory.java:673)
  at
  com.sun.deploy.security.CPCallbackHandler.showMixedTrustDialog(CPCallbackHandler.java:887)
  at
  com.sun.deploy.security.CPCallbackHandler.access$1200(CPCallbackHandler.java:74)
  at
  com.sun.deploy.security.CPCallbackHandler$ParentCallback.checkAllowed(CPCallbackHandler.java:352)
  at
  com.sun.deploy.security.CPCallbackHandler$ParentCallback.check(CPCallbackHandler.java:327)
• locked
  <7f4734908>
  (a
  com.sun.deploy.security.CPCallbackHandler$ParentCallback)
  at
  com.sun.deploy.security.CPCallbackHandler$ParentCallback.access$1800(CPCallbackHandler.java:128)
  at
  com.sun.deploy.security.CPCallbackHandler$ChildElement.checkResource(CPCallbackHandler.java:506)
  at
  com.sun.deploy.security.DeployURLClassPath$JarLoader.checkResource(DeployURLClassPath.java:816)
  at
  com.sun.deploy.security.DeployURLClassPath$JarLoader.getResource(DeployURLClassPath.java:889)
  at
  com.sun.deploy.security.DeployURLClassPath$JarLoader.findResource(DeployURLClassPath.java:860)
  at
  com.sun.deploy.security.DeployURLClassPath$1.next(DeployURLClassPath.java:265)
  at
  com.sun.deploy.security.DeployURLClassPath$1.hasMoreElements(DeployURLClassPath.java:276)
  at
  java.net.URLClassLoader$3$1.run(URLClassLoader.java:416)
  at
  java.security.AccessController.doPrivileged(Native
  Method)
  at
  java.net.URLClassLoader$3.next(URLClassLoader.java:413)
  at
  java.net.URLClassLoader$3.hasMoreElements(URLClassLoader.java:438)
  at
  sun.misc.CompoundEnumeration.next(CompoundEnumeration.java:27)
  at
  sun.misc.CompoundEnumeration.hasMoreElements(CompoundEnumeration.java:36)
  at
  org.apache.logging.log4j.core.config.plugins.ResolverUtil.findInPackage(ResolverUtil.java:240)
  at
  org.apache.logging.log4j.core.config.plugins.PluginManager.collectPlugins(PluginManager.java:174)
  at
  org.apache.logging.log4j.core.config.plugins.PluginManager.collectPlugins(PluginManager.java:130)
  at
  org.apache.logging.log4j.core.config.BaseConfiguration.start(BaseConfiguration.java:152)
  at
  org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:341)
• locked
  <7f42b0750>
  (a
  org.apache.logging.log4j.core.LoggerContext)
  at
  org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:386)
• locked
  <7f42b0750>
  (a
  org.apache.logging.log4j.core.LoggerContext)
  at
  org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:149)
  at
  org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:84)
  at
  org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:35)
  at
  org.apache.logging.log4j.LogManager.getLogger(LogManager.java:444)
  at
  org.apache.logging.log4j.LogManager.getLogger(LogManager.java:389)
  at
  de.mmis.utilities.genericPublisher.GenericPublisher.<clinit>(GenericPublisher.java:47)
  at
  de.mmis.utilities.genericPublisher.GenericPublisherMain.main(GenericPublisherMain.java:44)
  at
  sun.reflect.NativeMethodAccessorImpl.invoke0(Native
  Method)
  at
  sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
  at
  sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
  at
  java.lang.reflect.Method.invoke(Method.java:597)
  at
  com.sun.javaws.Launcher.executeApplication(Launcher.java:1953)
  at
  com.sun.javaws.Launcher.executeMainClass(Launcher.java:1886)
  at
  com.sun.javaws.Launcher.doLaunchApp(Launcher.java:1648)
  at
  com.sun.javaws.Launcher.run(Launcher.java:141)
  at
  java.lang.Thread.run(Thread.java:695)

The problem seems to be line 240 in the findPackage(...) method in
core.config.plugins.ResolverUtil.
We set a breakpoint in line 234 and stepped through the program. We found
out that the Enumeration<URL> urls->enums->[0] ->val$e -> this$0 ->path (ArrayList) consists of the values:

[file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jsfd.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/classes.jar,
file:/System/Library/Frameworks/JavaVM.framework/Versions/A/Frameworks/JavaRuntimeSupport.framework/Versions/A/Resources/Java/JavaRuntimeSupport.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/ui.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/laf.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/sunrsasign.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/jsse.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home/lib/jce.jar,
file:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Classes/charsets.jar]

This (probably) leads the method to try to access code inside the jar files.
Because these jars ore not signed this causes a warning if you start the
webstart application that says that you try to run both signed and unsigned
contents.
I tried to fix this by commenting the whole method. This caused a Null-Pointer-Exception. I think in this context you might need also to think about the return statement in th catch clause in line 237. If the IOException will be thrown, no global side effects could have happened, so this event will also probably cause a
Null-Pointer-Exception.