CVE-2021-4104 : Exploit Details and Defense Strategies
Learn about CVE-2021-4104, a critical vulnerability in Apache Log4j 1.2 that allows remote code execution. Upgrade to Log4j 2 to secure your systems.
Apache Log4j 1.2 is vulnerable to deserialization of untrusted data in the JMSAppender, allowing remote code execution. Users of Log4j 1.2 are advised to upgrade to Log4j 2.
Understanding CVE-2021-4104
JMSAppender in Log4j 1.2 is vulnerable to deserialization of untrusted data when the attacker can manipulate the Log4j configuration, leading to remote code execution.
What is CVE-2021-4104?
CVE-2021-4104 is a vulnerability in Apache Log4j 1.2 that allows an attacker to perform JNDI requests by providing certain configurations to the JMSAppender, resulting in remote code execution.
The Impact of CVE-2021-4104
The vulnerability affects Apache Log4j 1.2 versions, specifically when configured to use JMSAppender. Successful exploitation could lead to remote code execution on the affected system.
Technical Details of CVE-2021-4104
Apache Log4j 1.2 is vulnerable to deserialization attacks when untrusted data is deserialized by the JMSAppender, enabling attackers to execute arbitrary code.
Vulnerability Description
The issue arises due to improper handling of deserialization in the JMSAppender component of Log4j 1.2, allowing attackers to trigger remote code execution.
Affected Systems and Versions
Vendor: Apache Software Foundation Product: Apache Log4j 1.x Affected Version: Apache Log4j 1.2 1.2.x (specifically when configured to use JMSAppender).
Exploitation Mechanism
Attackers with write access to the Log4j configuration can provide malicious TopicBindingName and TopicConnectionFactoryBindingName configurations to exploit the vulnerability.
Mitigation and Prevention
Users are strongly advised to upgrade from Apache Log4j 1.2 to Log4j 2 as 1.2 has reached end of life.
Immediate Steps to Take
Upgrade Log4j to version 2 to mitigate the vulnerability and prevent potential remote code execution attacks.
Long-Term Security Practices
Regularly update software components and follow secure coding practices to prevent similar vulnerabilities in the future.
Patching and Updates
Stay informed about security updates for Log4j and apply patches promptly to address any known vulnerabilities.