Log4j mitigation

Tue Dec 14 20:05:52 UTC 2021

> On Dec 14, 2021, at 06:54 , Doug McIntyre <merlyn at geeks.org> wrote:
> 
> On Mon, Dec 13, 2021 at 11:38:04AM -0800, Owen DeLong via NANOG wrote:
>>> On Dec 11, 2021, at 04:11 , Nick Hilliard <nick at foobar.org> wrote:
> ...
>>> https://logging.apache.org/log4j/2.x/security.html
>>> 
>>> 1. upgrade log4j to 2.15.0 and restart all java apps
>>> 2. start java with "-D log4j2.formatMsgNoLookups=true" (v2.10+ only)
>>> 3. start java with "LOG4J_FORMAT_MSG_NO_LOOKUPS=true" environment variable (v2.10+ only)
>>> 4. zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class
>>> 
>>> There's a lot of scanning going on at the moment, so if you have an exposed java instance running something which includes log4j2, you may already be compromised.
>>> 
>>> Nick
>> 
>> Alternatively, this incantation solved the problem on my linux server:
>> 
>> rpm -e log4j12 ant-apache-log4j log4j
> 
> 
> There are many software setups that bundle their own log4j.jar without
> bothering to go through the OS package manager....
> 
> $ rpm -qa | fgrep log4j
> $
> 
> $ find / -name log4j*jar
> ....system/log4j/log4j/log4j/1.2.17/log4j-1.2.17.jar
> 
> (obviously an old system due to the commands used and version found,
> and nor will it get patches available because of vendor...).
> 
> Sorta like playing whack-a-mole with jquery.js (another package with
> lots of security history that seems to be copied _everywhere_ without
> registring it with the OS package manager). 
> 
> So, the exercise becomes _finding_ the software that uses it, and then
> doing the configs that defang JNDI everywhere you find it.

YMMV… Find didn’t find anything named log4j\*jar after I did my rpm -e.

Owen