CVE-2016-10194 in festivaltts4r Gem
Summary
by MITRE
The festivaltts4r gem for Ruby allows remote attackers to execute arbitrary commands via shell metacharacters in a string to the (1) to_speech or (2) to_mp3 method in lib/festivaltts4r/festival4r.rb.
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Analysis
by VulDB Data Team • 09/03/2020
The CVE-2016-10194 vulnerability resides within the festivaltts4r ruby gem, a component designed to interface with the festival text-to-speech system. This gem provides ruby developers with functionality to convert text into speech through festival's backend services. The vulnerability manifests in the to_speech and to_mp3 methods located in the lib/festivaltts4r/festival4r.rb file, where input validation fails to properly sanitize user-provided strings before passing them to underlying shell commands. This represents a classic command injection flaw that allows remote attackers to execute arbitrary system commands with the privileges of the user running the ruby application.
The technical exploitation of this vulnerability occurs through the manipulation of shell metacharacters within input strings passed to the affected methods. When a user provides malicious input containing characters such as semicolons, pipes, or backticks, these metacharacters are interpreted by the shell and executed as part of the command line. The vulnerability maps directly to CWE-78, which describes improper neutralization of special elements used in OS commands, and specifically aligns with the broader category of command injection attacks. Attackers can leverage this flaw to execute arbitrary commands on the target system, potentially gaining full control over the application server or underlying infrastructure.
The operational impact of this vulnerability extends beyond simple code execution, as it can enable attackers to perform reconnaissance, escalate privileges, and establish persistent access to the compromised system. Remote exploitation means that attackers do not require physical access or prior authentication to exploit the vulnerability. The attack surface includes any application using the festivaltts4r gem that accepts user input through the affected methods, making it particularly dangerous in web applications or services that process user-generated content. This vulnerability directly maps to several ATT&CK techniques including T1059.001 for command and script interpreter, T1068 for exploit for privilege escalation, and T1566 for spearphishing with a malicious attachment or link.
Mitigation strategies for CVE-2016-10194 require immediate remediation through updating to a patched version of the festivaltts4r gem or implementing proper input sanitization measures. Organizations should ensure that all user-provided input is properly escaped or sanitized before being passed to shell commands. The implementation of a secure coding practice including parameterized commands or command whitelisting can effectively prevent this class of vulnerability. Additionally, network segmentation and application firewalls can provide defense-in-depth measures to limit the potential impact of successful exploitation. Regular security audits and dependency monitoring should be implemented to identify and remediate similar vulnerabilities in other third-party libraries. The vulnerability demonstrates the critical importance of input validation and proper command execution practices in preventing remote code execution through shell injection flaws.