Taking the world by storm: Log4Shell vulnerability CVE-2021-44228

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Friday Nov 10th morning the news of Log4Shell vulnerability (CVE-2021-44228) started to appear, a few hours later several sites were already having their IPs shown in Github, examples were TSLA, twitter, Apple, Amazon, Twitter.

This vulnerability is very much related to one topic I usually post about it here, which is JNDI lookup, and LDAP in the context of EJB for returning Java Objects – aka serialization. And CVE 44228 is basically this, a JNDI lookup().

Updating your JDK for the latest will not save your from this one, but depending on the JDK it will much easier to get it. Explanation:

JDK versionsVulnerability
<8u121Starting with Java 8u121 remote codebase were no longer permitted by default for RMI (but not LDAP).
<=8u191There is a direct path from a controlled JNDI lookup to remote classloading of arbitrary code
8u191>RMI, References and object construction can still happen. Example: Apache Xbean BeanFactory

Solutions were already much much already described, basically updating the log4j or removing the JNDI lookup class. Since from log4j 2.15.0, this behavior has been disabled by default.

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