Apache Tomcat CVE-2018-14742 Deserialization RCE Vulnerability Analysis and POC

CVE-2018-14742 Vulnerability Summary Vulnerability Overview This vulnerability exists in the class of Apache Tomcat, specifically within the method. An attacker can craft a malicious configuration file to trigger a deserialization vulnerability during application deployment, leading to arbitrary code execution. The core of the vulnerability lies in Tomcat's failure to sufficiently validate the attribute when parsing the element in . This allows the specification of arbitrary class names, enabling exploitation via deserialization attacks. Scope of Impact Affected Versions: Apache Tomcat 8.5.x (below 8.5.37), 9.0.x (below 9.0.17) Unaffected Versions: Tomcat 8.5.37+, 9.0.17+ Trigger Condition: Requires deployment of a WAR package or directory-based application containing a malicious Attack Surface: Limited to locally deployed applications; requires permission to upload/deploy WAR packages Remediation 1. Upgrade Version: - Tomcat 8.5.x → Upgrade to 8.5.37 or higher - Tomcat 9.0.x → Upgrade to 9.0.17 or higher 2. Temporary Mitigation Measures: - Disable the element in (if not required) - Restrict permissions on deployment directories to prevent unauthorized WAR package uploads - Use a WAF to filter anomalous values 3. Configuration Hardening: - Set in to prevent symbolic link attacks - Enable to restrict source IPs POC Code (Full Extraction) > Note: This POC exploits the deserialization capabilities of by injecting a malicious JDBC URL via the parameter, triggering remote code execution. In actual attacks, this can be replaced with other deserializable classes (e.g., chains). Additional Notes This vulnerability has been officially patched by Apache; immediate upgrade is recommended. If upgrading is not possible, strictly audit all files in deployed applications. Monitor logs for anomalous loading behavior.

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Apache Tomcat CVE-2018-14742 Deserialization RCE Vulnerability Analysis and POC

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