CVE-2021-4104

Published: 14 December 2021

JMSAppender in Log4j 1.2 is vulnerable to deserialization of untrusted data when the attacker has write access to the Log4j configuration. The attacker can provide TopicBindingName and TopicConnectionFactoryBindingName configurations causing JMSAppender to perform JNDI requests that result in remote code execution in a similar fashion to CVE-2021-44228. Note this issue only affects Log4j 1.2 when specifically configured to use JMSAppender, which is not the default. Apache Log4j 1.2 reached end of life in August 2015. Users should upgrade to Log4j 2 as it addresses numerous other issues from the previous versions.

Notes

This issue is similar to CVE-2021-44228, but for log2j < 2.0 and
is only vulnerable if configured to use JMSAppender.
For an environment to be vulnerable, an attacker would need write access
to the log4j.properties configuration file to specifically enable the JMS
Appender and configure it with a JNDI lookup to a third party server. If
an attacker has write access to the log4j.properties configuration file,
there are also other configuration options that can be used to perform
code execution attacks. We therefore recommend configuration files be set
with appropriate permissions to only permit being modified by trusted
individuals.

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-4104
• https://github.com/apache/logging-log4j2/pull/608#issuecomment-990494126
• https://www.openwall.com/lists/oss-security/2021/12/13/2
• https://ubuntu.com/security/notices/USN-5223-1
• https://ubuntu.com/security/notices/USN-5223-2
• NVD
• Launchpad
• Debian

Bugs

• https://bugzilla.redhat.com/show_bug.cgi?id=2031667