CVE-2013-1898 in thumbshooter
Summary
by MITRE
lib/thumbshooter.rb in the Thumbshooter 0.1.5 gem for Ruby allows remote attackers to execute arbitrary commands via shell metacharacters in a URL.
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Analysis
by VulDB Data Team • 02/25/2019
The vulnerability identified as CVE-2013-1898 resides within the Thumbshooter gem version 0.1.5 for Ruby, representing a critical command injection flaw that enables remote attackers to execute arbitrary system commands. This vulnerability specifically affects the lib/thumbshooter.rb component which processes URLs and fails to properly sanitize input parameters before incorporating them into system commands. The flaw stems from insufficient validation and sanitization of user-supplied URL data, creating an environment where malicious actors can inject shell metacharacters that get interpreted by the underlying operating system.
The technical implementation of this vulnerability demonstrates a classic command injection weakness that aligns with CWE-77, which describes improper neutralization of special elements used in a command. When the Thumbshooter gem processes a URL containing malicious shell metacharacters such as semicolons, ampersands, or backticks, these characters are not properly escaped or filtered before being passed to system execution functions. This allows attackers to chain additional commands or manipulate the execution flow of the target system, potentially leading to complete system compromise. The vulnerability operates at the application layer where Ruby code interacts with system commands, making it particularly dangerous as it can leverage the privileges of the executing process.
From an operational impact perspective, this vulnerability presents a severe risk to systems running applications that utilize the Thumbshooter gem, particularly web applications that generate thumbnails from remote URLs or process user-provided web addresses. Attackers can exploit this flaw to execute arbitrary commands on the server, potentially leading to data exfiltration, system persistence, privilege escalation, or complete system takeover. The remote nature of the attack means that threat actors do not require physical access or prior authentication to exploit this vulnerability, making it highly attractive for automated exploitation campaigns. Organizations utilizing this gem in production environments face significant exposure, especially if the affected applications are publicly accessible or handle untrusted user input.
Mitigation strategies for CVE-2013-1898 should prioritize immediate remediation through updating to a patched version of the Thumbshooter gem or implementing comprehensive input validation and sanitization measures. Security professionals should implement proper parameter validation that filters or escapes special shell characters before any system command execution occurs. The implementation of secure coding practices including the use of shell command libraries that properly handle escaping and quoting of parameters can prevent this class of vulnerability. Additionally, network segmentation and application firewalls should be deployed to limit access to vulnerable applications, while regular security assessments should verify that no other components within the application stack are susceptible to similar command injection flaws. This vulnerability also highlights the importance of supply chain security and the need for thorough vulnerability scanning of all third-party libraries and gems used in Ruby applications, aligning with ATT&CK technique T1190 for exploitation of vulnerabilities in commonly used software components. Organizations should establish processes for monitoring and updating gem dependencies to prevent exploitation of known vulnerabilities in their software supply chain.