With log4j 2.15.0 this should be fixed and by default all expansions on log messages were disabled: https://issues.apache.org/jira/browse/LOG4J2-3198
----- Uwe Schindler Achterdiek 19, D-28357 Bremen https://www.thetaphi.de eMail: [email protected] > -----Original Message----- > From: Uwe Schindler <[email protected]> > Sent: Friday, December 10, 2021 11:10 AM > To: [email protected] > Subject: RE: Log4J RCE vulnerability > > In general the sysprop "log4j2.formatMsgNoLookups=true" fix is the only > correct fix (maybe add it to the bootstrap class of solr). Updating log4j is > not > really needed. This prevents any of those shit. There's no reason ever to > parse > ${} escapes in log messages. The only place where this can be used is the > format pattern in the config file, but WTF was the idea behind that to pass > ALL > log messages through the expansion? > > Man man, SNEAKY log4j!!! 😊 > > Uwe > > ----- > Uwe Schindler > Achterdiek 19, D-28357 Bremen > https://www.thetaphi.de > eMail: [email protected] > > > -----Original Message----- > > From: Uwe Schindler <[email protected]> > > Sent: Friday, December 10, 2021 10:35 AM > > To: [email protected] > > Subject: RE: Log4J RCE vulnerability > > > > Hi, > > > > I did some checks: > > - The problem also exists with logging parameters, so it is also executed > > if you > > call (which is IMHO a design failure in log4j, the reason for this is that > > the > > expansion is happending on printing the complete formatted log string to the > > output file): logger.info("Foobar: {}", "${badPayload}") > > - It also triggers if the message of an exception has a malicous payload! So > > happens easily if some input is validated and there's an > > IllegalArgumentException logged on validation errors > > > > To try out, and see it live do the following (can be done on any server, I > > tested > > it on my own servers, worked always): > > > > Start a local netcat: > > root@pangaea-mw1:~# nc -lp 1234 > > > > Go to any user interface of you application, e.g. solr or send a query > containing > > this payload, e.g. as part of a query string that is logged: > > ${jndi:ldap://127.0.0.1:1234/abc} > > > > You will see cryptic text with emojis in the above netcat output. This shows > > that it definitely made an external request. > > > > We should fix this in 8.11 by doing the following: > > a) add "-Dlog4j2.formatMsgNoLookups=true" to Solr's start scripts (easy > > fix, I > > did the same on all my servers). Add this to the *main shell script*, not > > to the > > solr.sh.in files, as those are modified by users. > > b) possibly update log4j, but with above fix it's not urgent and should not > > be > > done in 10.0. > > > > Uwe > > > > ----- > > Uwe Schindler > > Achterdiek 19, D-28357 Bremen > > https://www.thetaphi.de > > eMail: [email protected] > > > > > -----Original Message----- > > > From: Bram Van Dam <[email protected]> > > > Sent: Friday, December 10, 2021 8:31 AM > > > To: [email protected] > > > Subject: Log4J RCE vulnerability > > > > > > Heads up: > > > > > > Seems like there's a pretty severe remote code execution vulnerability > > > [1] in Log4J. Basically any application that uses log4j and that allows > > > user input to be injected into a logging string is susceptible. This > > > probably includes Solr. > > > > > > Further interesting discussion on Hacker News [2] > > > > > > [1] https://www.lunasec.io/docs/blog/log4j-zero-day/ > > > [2] https://news.ycombinator.com/item?id=29504755 > > > > > > > > > - Bram > > > > > > --------------------------------------------------------------------- > > > To unsubscribe, e-mail: [email protected] > > > For additional commands, e-mail: [email protected] > > > > > > --------------------------------------------------------------------- > > To unsubscribe, e-mail: [email protected] > > For additional commands, e-mail: [email protected] > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [email protected] > For additional commands, e-mail: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
