oss-security - Re: CVE-2021-44228: Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints

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Message-ID: <c24bb38a-bd87-3bcb-7831-811e8d8d5405@eenterphace.org>
Date: Fri, 10 Dec 2021 11:29:48 +0100
From: Moritz Bechler <mbechler@...terphace.org>
To: oss-security@...ts.openwall.com, rgoers@...che.org
Subject: Re: CVE-2021-44228: Apache Log4j2 JNDI features do not
 protect against attacker controlled LDAP and other JNDI related endpoints

Hello,


> In previous releases (>2.10) this behavior can be mitigated by setting system property "log4j2.formatMsgNoLookups" to “true” or by removing the JndiLookup class from the classpath (example: zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class). Java 8u121 (see https://www.oracle.com/java/technologies/javase/8u121-relnotes.html) protects against remote code execution by defaulting "com.sun.jndi.rmi.object.trustURLCodebase" and "com.sun.jndi.cosnaming.object.trustURLCodebase" to "false".


Please note, that Java 8u121+ does not necessarily protect against 
remote code execution. There are known exploitation vectors using local 
naming factories, e.g. a XBean BeanFactory (bundled with Tomcat). Also, 
both RMI and LDAP lookups can be made to perform Java deserialization on 
remote input and therefore there is a good chance for secondary RCE 
exploits.


Moritz

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