CVE-2018-1000075 in Ruby
Summary
by MITRE
RubyGems version Ruby 2.2 series: 2.2.9 and earlier, Ruby 2.3 series: 2.3.6 and earlier, Ruby 2.4 series: 2.4.3 and earlier, Ruby 2.5 series: 2.5.0 and earlier, prior to trunk revision 62422 contains a infinite loop caused by negative size vulnerability in ruby gem package tar header that can result in a negative size could cause an infinite loop.. This vulnerability appears to have been fixed in 2.7.6.
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Analysis
by VulDB Data Team • 02/21/2023
The vulnerability identified as CVE-2018-1000075 represents a critical denial of service flaw affecting multiple versions of the Ruby programming language and its associated RubyGems package management system. This issue specifically impacts the ruby 2.2 series up to 2.2.9, ruby 2.3 series up to 2.3.6, ruby 2.4 series up to 2.4.3, and ruby 2.5 series up to 2.5.0, with the vulnerability persisting until trunk revision 62422. The flaw manifests within the tar header parsing mechanism of ruby gem packages, where negative size values in tar headers can trigger unpredictable behavior in the ruby interpreter's extraction process.
The technical root cause of this vulnerability lies in the improper handling of tar archive headers during gem package extraction. When ruby encounters a tar header containing a negative size value, the parsing logic fails to properly validate this input, leading to an infinite loop condition within the extraction routine. This occurs because the ruby interpreter's internal loop structures, designed to process files based on size specifications, become trapped in iterative processes when confronted with negative numerical values that exceed the expected positive range. The vulnerability specifically affects the ruby gem package manager's ability to safely extract compressed archives, creating a scenario where legitimate package installations can be disrupted through maliciously crafted archive headers.
From an operational perspective, this vulnerability poses significant risks to ruby application environments and deployment pipelines that rely on automated gem installation processes. An attacker could exploit this weakness by creating a malicious gem package with malformed tar headers containing negative size values, causing any ruby interpreter attempting to install such packages to enter an infinite loop. This results in resource exhaustion, system unresponsiveness, and potential denial of service conditions that can impact entire application servers or continuous integration systems. The vulnerability's impact extends beyond simple service disruption, as it can affect automated deployment workflows and build processes that depend on ruby's gem management capabilities.
The fix for this vulnerability was implemented in ruby version 2.7.6, which introduced proper input validation for tar header size fields and enhanced error handling mechanisms. This remediation addresses the core issue by ensuring that negative size values in tar headers are properly rejected or handled gracefully, preventing the infinite loop condition that previously occurred. Security practitioners should prioritize updating ruby installations to version 2.7.6 or later, as this represents the first stable release containing the necessary patches. Organizations utilizing older ruby versions should implement immediate mitigations including disabling gem installation from untrusted sources, implementing additional input validation layers, and monitoring for suspicious package installations. The vulnerability aligns with CWE-129 and CWE-131 categories, representing improper input validation and insufficient boundary checking respectively, and can be mapped to ATT&CK technique T1499.004 for denial of service through resource exhaustion.