CVE-2016-1240 in Tomcat
Summary
by MITRE
The Tomcat init script in the tomcat7 package before 7.0.56-3+deb8u4 and tomcat8 package before 8.0.14-1+deb8u3 on Debian jessie and the tomcat6 and libtomcat6-java packages before 6.0.35-1ubuntu3.8 on Ubuntu 12.04 LTS, the tomcat7 and libtomcat7-java packages before 7.0.52-1ubuntu0.7 on Ubuntu 14.04 LTS, and tomcat8 and libtomcat8-java packages before 8.0.32-1ubuntu1.2 on Ubuntu 16.04 LTS allows local users with access to the tomcat account to gain root privileges via a symlink attack on the Catalina log file, as demonstrated by /var/log/tomcat7/catalina.out.
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Analysis
by VulDB Data Team • 06/21/2024
The vulnerability described in CVE-2016-1240 represents a critical privilege escalation flaw affecting Apache Tomcat installations on various Linux distributions. This issue stems from improper handling of log file permissions within the Tomcat init scripts, creating a dangerous symlink attack vector that allows local users with tomcat account access to escalate their privileges to root level. The vulnerability specifically targets the catalina.out log file located at /var/log/tomcat7/catalina.out, though similar issues exist across multiple Tomcat versions and operating system variants.
The technical flaw manifests through a classic symlink race condition attack pattern where an attacker with access to the tomcat user account can manipulate symbolic links to gain unauthorized root access. When the Tomcat init script executes and processes the catalina.out log file, it follows symbolic links without proper validation, allowing an attacker to redirect log file operations to arbitrary locations. This vulnerability directly maps to CWE-59 and CWE-273, which address improper handling of symbolic links and the creation of world-writable files respectively. The attack leverages the principle of least privilege violation by enabling a local user to bypass normal access controls and execute commands with root privileges.
The operational impact of this vulnerability is severe as it transforms a local user account into a root-level attacker without requiring additional credentials or complex exploitation techniques. Attackers can leverage this privilege escalation to modify system files, install malicious software, or establish persistent backdoors. The vulnerability affects multiple Debian and Ubuntu releases including Debian jessie and various Ubuntu LTS versions, making it particularly widespread. Organizations running affected Tomcat installations face significant risk of system compromise, especially in environments where the tomcat user account has access to system resources or where users might be granted access to the tomcat account for legitimate administrative purposes.
Mitigation strategies for this vulnerability require immediate patching of affected Tomcat packages to versions containing the security fixes. System administrators should ensure all affected tomcat7, tomcat8, tomcat6, and related packages are updated to their patched versions, specifically targeting the releases mentioned in the CVE description. Additional protective measures include implementing proper file system permissions for log directories, removing unnecessary symbolic links, and monitoring for suspicious file access patterns. Organizations should also consider implementing privilege separation techniques and regular security audits to detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically T1068, which addresses 'Exploitation for Privilege Escalation', making it a critical target for defensive security measures and incident response protocols.