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: <9aa6ae9f-fa20-0804-1511-cb81d1491cc8@eenterphace.org>
Date: Fri, 10 Dec 2021 19:55:34 +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

Hi,


> 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".
> 

I also believe this should be Java 8u191, as only then remote 
classloading for LDAP was disabled by default. Only since then the 
direct remote classloading attack vector through JNDI injection is 
mitigated.

I put together a little post on the different JNDI attack vectors and 
how which Java versions are affected:
<https://mbechler.github.io/2021/12/10/PSA_Log4Shell_JNDI_Injection/>

TLDR:
- Direct remote classloading through RMI up to 8u121 (and corresponding 
patch versions)
- Direct remote classloading through LDAP up to 8u191 (and corresponding 
patch versions)
- Runtime environment may provide exploitable local JNDI factory classes 
(Tomcat, WebSphere known)
- Deserialization attacks are possible (if no global filter is applied), 
independent of runtime version

=> Do not rely on newer Java versions for mitigation, do patch 
immediately (or remove/disable the functionality)



Moritz

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