CVE-2020-12640 in RoundCube
Summary
by MITRE
Roundcube Webmail before 1.4.4 allows attackers to include local files and execute code via directory traversal in a plugin name to rcube_plugin_api.php.
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Analysis
by VulDB Data Team • 05/05/2020
The vulnerability identified as CVE-2020-12640 affects Roundcube Webmail versions prior to 1.4.4 and represents a critical directory traversal flaw that enables remote code execution through improper input validation in plugin handling. This vulnerability specifically targets the rcube_plugin_api.php component which processes plugin names without adequate sanitization, creating an avenue for attackers to manipulate file inclusion paths. The flaw resides in how the application handles plugin identifiers during the plugin loading process, where user-supplied input is directly incorporated into file system operations without proper validation or sanitization measures.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious plugin name containing directory traversal sequences such as ../ or ..\ that bypass normal path validation mechanisms. When Roundcube processes this malformed plugin identifier, the application attempts to load the specified plugin from a location determined by the traversal sequence, potentially allowing access to arbitrary files on the server filesystem. This vulnerability can be leveraged to include local files and subsequently execute arbitrary code on the target system, as the plugin loading mechanism does not properly validate or sanitize the plugin name parameter before using it in file system operations.
The operational impact of CVE-2020-12640 extends beyond simple privilege escalation as it provides attackers with complete control over the affected webmail server. An attacker can leverage this vulnerability to execute arbitrary commands, potentially leading to full system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability affects the core plugin architecture of Roundcube, making it particularly dangerous as it can be exploited to load malicious plugins or access sensitive system files that should remain protected. This type of vulnerability is classified under CWE-22 as "Improper Limitation of a Pathname to a Restricted Directory" and aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as successful exploitation results in arbitrary code execution capabilities.
Security professionals should prioritize immediate patching of affected Roundcube installations to version 1.4.4 or later, which includes proper input validation and sanitization of plugin names. Additional mitigations include implementing web application firewalls with rules to detect and block directory traversal patterns, restricting file system permissions for the web application, and monitoring for suspicious plugin loading activities. The vulnerability demonstrates the critical importance of input validation in web applications and serves as a reminder of how seemingly minor flaws in parameter handling can lead to complete system compromise. Organizations using Roundcube should conduct thorough security assessments of their webmail environments and ensure proper network segmentation to limit the potential impact of such vulnerabilities. This vulnerability also highlights the need for comprehensive security testing including penetration testing and code reviews to identify similar path traversal issues in other components of the web application stack.