The Apache Software Foundation (ASF) has recently announced the release of critical updates for its Tomcat application server to resolve a significant security vulnerability. This flaw poses a risk by allowing remote attackers to execute arbitrary code, potentially compromising affected servers.
Apache Tomcat, an open-source web server and servlet container developed by ASF, is built on several Java EE specifications including Java Servlet and JavaServer Pages (JSP). It offers a fully Java-based HTTP web server environment, catering to Java applications.
The vulnerability, designated as CVE-2019-0232, specifically affects the Common Gateway Interface (CGI) Servlet when operating on Windows environments with the enableCmdLineArguments feature enabled. This flaw is rooted in a defect in how the Java Runtime Environment (JRE) handles command line arguments on Windows. While the CGI Servlet is disabled by default and enableCmdLineArguments is turned off in Tomcat versions 9.0.x, the vulnerability has still garnered an important classification rather than critical.
In light of this issue, ASF has taken proactive steps to ensure that the enableCmdLineArguments default setting is disabled across all iterations of Apache Tomcat. The scope of affected versions includes Apache Tomcat 9.0.0.M1 through 9.0.17, alongside 8.5.0 to 8.5.39, and 7.0.0 to 7.0.93. Conversely, versions released as Apache Tomcat 9.0.18 and later, 8.5.40 and later, and 7.0.94 and later are not impacted.
Exploiting this vulnerability could lead to remote attackers executing unauthorized commands on targeted Windows servers that are running susceptible versions of Apache Tomcat, resulting in a complete system compromise. The security threat was reported to the Apache Tomcat security team on March 3, 2019, by researchers from Nightwatch Cybersecurity. It was subsequently made public on April 10, 2019, following the release of updated software versions.
Apache Tomcat has since addressed this critical flaw through the launch of version 9.0.19, which included a fix to the issue, although it was technically resolved in version 9.0.18. Administrators are urgently advised to implement these updates without delay. In cases where immediate patching is not an option, it is essential to verify that the default value of enableCmdLineArguments for CGI Servlet initialization is set to false.
Understanding the implications of this vulnerability under the lens of the MITRE ATT&CK framework suggests potential adversary tactics such as initial access by exploiting misconfigurations, along with privilege escalation and command execution techniques. With cybersecurity being a primary concern for businesses today, staying informed and proactive in addressing such vulnerabilities is crucial for maintaining a secure operational posture.