NIFI-6301 - Added a SafeXMLConfiguration which disables XML DTDs whic… #3507
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alopresto
reviewed
May 30, 2019
| private static final String XXE_ERROR_MESSAGE = "XML configuration file contained an external entity. To eliminate XXE vulnerabilities, NiFi has external entity processing disabled."; | ||
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| @Override | ||
| public void initFileLocator(FileLocator loc) { |
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Moving public method below constructors.
alopresto
reviewed
May 30, 2019
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| @Override | ||
| public void read(Reader in) throws ConfigurationException, IOException { | ||
| try { |
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I refactored this duplicate code into a private method (see d67d6e4).
alopresto
reviewed
May 30, 2019
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| try { | ||
| // Act | ||
| // Service will fail to enable because test-xxe.xml contains a DTD |
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When I run the actual NiFi instance, the service is enabled. There is a bulletin shown, and a stacktrace in the error log, but the service is enabled.
2019-05-30 14:59:20,528 ERROR [Timer-Driven Process Thread-9] o.a.n.c.s.StandardControllerServiceNode StandardControllerServiceNode{controllerServiceHolder=org.apache.nifi:nifi-lookup-services-nar:1.10.0-SNAPSHOT, versionedComponentId=null, comment='', processGroup=StandardProcessGroup[identifier=0abd5fbf-016b-1000-00a7-2df537bcba2a], active=true} Failed to invoke @OnEnabled method due to org.apache.nifi.reporting.InitializationException: org.apache.commons.configuration2.ex.ConfigurationException: XML configuration file contained an external entity. To prevent XXE vulnerabilities, NiFi has external entity processing disabled.: {}
org.apache.nifi.reporting.InitializationException: org.apache.commons.configuration2.ex.ConfigurationException: XML configuration file contained an external entity. To prevent XXE vulnerabilities, NiFi has external entity processing disabled.
at org.apache.nifi.lookup.configuration2.CommonsConfigurationLookupService.onEnabled(CommonsConfigurationLookupService.java:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:142)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:130)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:75)
at org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotation(ReflectionUtils.java:52)
at org.apache.nifi.controller.service.StandardControllerServiceNode$2.run(StandardControllerServiceNode.java:435)
at org.apache.nifi.engine.FlowEngine$2.run(FlowEngine.java:110)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.commons.configuration2.ex.ConfigurationException: XML configuration file contained an external entity. To prevent XXE vulnerabilities, NiFi has external entity processing disabled.
at org.apache.nifi.security.xml.SafeXMLConfiguration.delegateRead(SafeXMLConfiguration.java:139)
at org.apache.nifi.security.xml.SafeXMLConfiguration.read(SafeXMLConfiguration.java:128)
at org.apache.commons.configuration2.io.FileHandler.loadFromStreamDirectly(FileHandler.java:1080)
at org.apache.commons.configuration2.io.FileHandler.loadFromStream(FileHandler.java:1055)
at org.apache.commons.configuration2.io.FileHandler.load(FileHandler.java:990)
at org.apache.commons.configuration2.io.FileHandler.load(FileHandler.java:973)
at org.apache.commons.configuration2.io.FileHandler.load(FileHandler.java:702)
at org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder.initFileHandler(FileBasedConfigurationBuilder.java:312)
at org.apache.commons.configuration2.builder.ReloadingFileBasedConfigurationBuilder.initFileHandler(ReloadingFileBasedConfigurationBuilder.java:185)
at org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder.initResultInstance(FileBasedConfigurationBuilder.java:291)
at org.apache.commons.configuration2.builder.FileBasedConfigurationBuilder.initResultInstance(FileBasedConfigurationBuilder.java:60)
at org.apache.commons.configuration2.builder.BasicConfigurationBuilder.createResult(BasicConfigurationBuilder.java:421)
at org.apache.commons.configuration2.builder.BasicConfigurationBuilder.getConfiguration(BasicConfigurationBuilder.java:285)
at org.apache.nifi.lookup.configuration2.CommonsConfigurationLookupService.onEnabled(CommonsConfigurationLookupService.java:119)
... 17 common frames omitted
Caused by: org.apache.commons.configuration2.ex.ConfigurationException: Error parsing file:/Users/alopresto/Workspace/nifi/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/resources/xxe_from_report.xml
at org.apache.commons.configuration2.XMLConfiguration.load(XMLConfiguration.java:1030)
at org.apache.commons.configuration2.XMLConfiguration.read(XMLConfiguration.java:996)
at org.apache.nifi.security.xml.SafeXMLConfiguration.lambda$read$1(SafeXMLConfiguration.java:129)
at org.apache.nifi.security.xml.SafeXMLConfiguration.delegateRead(SafeXMLConfiguration.java:135)
... 30 common frames omitted
Caused by: org.xml.sax.SAXParseException: DOCTYPE is disallowed when the feature "http://apache.org/xml/features/disallow-doctype-decl" set to true.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:257)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:339)
at org.apache.commons.configuration2.XMLConfiguration.load(XMLConfiguration.java:1023)
... 33 common frames omitted
2019-05-30 14:59:20,529 ERROR [Timer-Driven Process Thread-9] o.a.n.c.s.StandardControllerServiceNode Failed to invoke @OnEnabled method of XMLFileLookupService[id=0abec592-016b-1000-192b-309d4b845a7b] due to org.apache.nifi.reporting.InitializationException: org.apache.commons.configuration2.ex.ConfigurationException: XML configuration file contained an external entity. To prevent XXE vulnerabilities, NiFi has external entity processing disabled.
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After re-examination, the service stays in Enabling state.
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It may be better to implement this check as a validator instead. I'll add an XMLValidator which checks for XXEs.
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I've added an XXE validator to the CommonsConfigurationLookupService to do a simple check if the file contains an !ENTITY declaration. This in combination with the SafeXMLConfiguration will restrict XXE usage in XML configuration files in NiFi. |
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I built the PR successfully and ran a local instance.
I'm going to see if I can enforce the same expected behavior from the regular and whitespace XXE file on the multiline XXE file. I am also going to suppress the stacktrace unless |
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I was able to modify some code to allow multiline XXE attacks to be caught during validation. I updated the unit tests to accurately reflect this. I discovered another issue -- the
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Continuing to investigate. Not sure which timer/thread is triggering the validation, but you can see from the log it continues with cached data even after the controller service is deleted. |
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Leaving my additional commits here for now: alopresto/nifi/pr3507 |
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Was testing and had no problem verifying the new behavior in the XMLFileLookupService as a Reporting Task Controller Service:
But when I tried to create the controller service on the Process Group level, the UI would hang. Investigated by @mcgilman and this looks to be a result of https://issues.apache.org/jira/browse/NIFI-6341 which was fixed recently. |
…h may call external entities. NIFI-6301 - Fixed unit test. Added comments. NIFI-6301 - Removed unused rule from test. NIFI-6301 - Changed read() methods to use a boolean instead. Updated comments. NIFI-6301 - Fixing checkstyle errors.
…s that contain XXE declarations. Added unit tests and related XML test files.
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Added logging messages. Updated unit test.
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@alopresto I've verified the issue you had with the validator still running even after the controller service is deleted. It occurs for 'controller level' controller services, and not for process-group scoped controller services. It appears to occur for all validators, as I have tested it with another validator other than the XXE one I have added. I have opened a new Jira to track this issue: https://issues.apache.org/jira/browse/NIFI-6371 |
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Ran |
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…h may call external entities.
NIFI-6301 - Fixed unit test. Added comments.
NIFI-6301 - Removed unused rule from test.
NIFI-6301 - Changed read() methods to use a boolean instead. Updated comments.
NIFI-6301 - Fixing checkstyle errors.
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Enables X functionality; fixes bug NIFI-YYYY.
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