Vulnerability announcement | RCE vulnerability in Apache Log4j 2

Impacts

The affected services in E-MapReduce (EMR) clusters include Hive, Presto, Impala, Druid, Flink, Solr, Ranger, Storm, Oozie, Spark, and Zeppelin. Spark and Zeppelin are affected because they have a dependency on Hive.

Solution

Replace the Log4j 2 JAR file of your EMR cluster with the JAR file whose Log4j 2 version is 2.17.0. In addition, set the log4j2.formatMsgNoLookups parameter for the Hive and Spark services to true to disable the JNDI lookup feature. For more information about the procedure, see Procedure.

Procedure

Fix the vulnerability for an EMR cluster

1. Download the patch package patches-log4j.tar.gz.
2. Log on to the master node of your EMR cluster and place the package downloaded in Step 1 in the home directory of the hadoop user.
3. Run the following commands to switch to the hadoop user and decompress the package:

   su hadoop
   tar zxf patches-log4j.tar.gz

4. Run the following commands to open the hosts file in the patches directory. Then, add the hostnames of all the nodes in the cluster, such as emr-header-1 and emr-worker-1, to the hosts file. Enter one hostname in each line.

   cd patches
   vim hosts

   Sample file content:

   emr-header-1
   emr-worker-1
   emr-worker-2

5. Run the fix.sh script to fix the vulnerability:

   ./fix.sh

   After the script is run, the following information is returned:

   ### NOTICE: YOU CAN RESTORE THIS PATCH BY RUN RESTORE SCRIPT ABOVE
   $> sh ./restore.sh 20211213001755
   ### DONE

   If you want to perform a rollback, run the following command:

   ./restore.sh 20211213001755

   Note For jobs that are running in YARN, such as Spark Streaming or Flink jobs, you must perform a rolling restart on YARN NodeManager after the jobs are stopped.
6. Restart services.
   Restart the affected services, including Hive, Presto, Impala, Druid, Flink, Solr, Ranger, Storm, Oozie, Spark, and Zeppelin.

   For example, choose Actions > Restart All Components in the upper-right corner of the Hive service page to restart the Hive service.

Fix the vulnerability for a gateway cluster

Fix the vulnerability when you create a cluster or scale out an existing cluster

When you create an EMR cluster, you can add a bootstrap action in the EMR console to fix the vulnerability. When you scale out an existing cluster, the system automatically fixes the vulnerability. When you create an EMR cluster, perform the following steps:

1. Download the patches-log4j.tar.gz package and the bootstrap_log4j.sh script file and upload them to an Object Storage Service (OSS) path.
   In this example, the package and script file are uploaded to oss://<bucket-name>/path/to/.
2. Add a bootstrap action in the EMR console. For more information, see Manage bootstrap actions.
   In the Add Bootstrap Actions dialog box, configure the parameters.

   Parameter	Description
   Name	The name of the bootstrap action that you want to add. For example, you can set this parameter to fixlog4jvulnerability.
   Script Path	The OSS path where the script file is stored. You must specify this parameter in the oss://**/*.sh format. In this example, the path is oss://<bucket-name>/path/to/bootstrap_log4j.sh.
   Parameter	The parameter of the bootstrap action script. The parameter is used to specify the value of the variable that is referenced in the script. In this example, the parameter is oss://<bucket-name>/path/to/patches-log4j.tar.gz.
   Target Nodes	Select Cluster.
   Execution At	Select After Component Startup.
   Execution Failure Policy	Select Proceed.

3. After you create the cluster, restart the Hive, Presto, Impala, Druid, Flink, Solr, Ranger, Storm, Oozie, Spark, and Zeppelin services.