CVE-2014-5003 in ciborg Gem
Summary
by MITRE
chef/travis-cookbooks/ci_environment/perlbrew/recipes/default.rb in the ciborg gem 3.0.0 for Ruby allows local users to write to arbitrary files and gain privileges via a symlink attack on /tmp/perlbrew-installer.
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Analysis
by VulDB Data Team • 12/21/2019
The vulnerability identified as CVE-2014-5003 resides within the ciborg gem version 3.0.0, specifically in the chef/travis-cookbooks/ci_environment/perlbrew/recipes/default.rb script. This flaw represents a classic symlink attack vector that enables local attackers to manipulate file operations and escalate privileges. The vulnerability occurs during the perlbrew installation process where the system creates temporary files in the /tmp directory without proper security controls. The attack leverages the predictable naming convention of temporary files and the lack of atomic operations during file creation, allowing malicious users to establish symbolic links that redirect the installation process to write arbitrary files with elevated privileges.
The technical implementation of this vulnerability stems from insufficient input validation and improper temporary file handling within the perlbrew installation script. When the ciborg gem executes the default recipe, it attempts to download and execute the perlbrew-installer script in the /tmp directory. However, the script does not properly validate the existence of the target file or implement secure temporary file creation mechanisms. This creates a window of opportunity where a local attacker can create a symbolic link named /tmp/perlbrew-installer that points to a file they control, such as a system configuration file or a script in a privileged location. The vulnerability directly maps to CWE-367, which describes the Time-of-Check to Time-of-Use (TOCTOU) race condition, and CWE-22, which covers improper limitation of a pathname to a restricted directory. The flaw operates under the principle that the system checks for file existence and then uses that file without revalidating the check, allowing an attacker to substitute the file between these operations.
The operational impact of CVE-2014-5003 extends beyond simple privilege escalation to encompass potential system compromise and persistent access. A local attacker who successfully exploits this vulnerability can gain elevated privileges and potentially establish a foothold within the system that persists across reboots. The attack requires local system access but does not need network connectivity, making it particularly dangerous in environments where local privilege escalation is not properly restricted. The vulnerability affects systems running the ciborg gem version 3.0.0 or earlier, which were commonly used in continuous integration environments and automated deployment scenarios. Organizations using this gem in production environments face significant risk, as the attack can be executed by any user with local access to the system, potentially compromising the integrity of the entire CI/CD pipeline. The attack aligns with ATT&CK technique T1068, which describes the use of local privilege escalation techniques, and T1548.001, which covers abuse of system privileges.
Mitigation strategies for CVE-2014-5003 should focus on immediate remediation through version updates and implementation of secure coding practices. The primary solution involves upgrading to a patched version of the ciborg gem that addresses the insecure temporary file handling. Organizations should also implement proper file permission controls and secure temporary file creation mechanisms within their CI/CD environments. The remediation process should include verification that no symbolic links exist in the /tmp directory that could be exploited by the vulnerable installation process. Additional protective measures include implementing mandatory access controls, restricting local user privileges, and monitoring for unauthorized file system modifications. Security teams should also consider implementing runtime protection mechanisms that can detect and prevent symbolic link attacks. The vulnerability highlights the importance of following secure coding practices such as using atomic file creation operations and avoiding predictable temporary file names. Organizations should conduct regular security assessments of their dependency management processes to identify and remediate similar vulnerabilities in other gems and libraries that may be subject to similar attacks.