CVE-2016-7954 in Bundler
Summary
by MITRE
Bundler 1.x might allow remote attackers to inject arbitrary Ruby code into an application by leveraging a gem name collision on a secondary source. NOTE: this might overlap CVE-2013-0334.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-7954 affects the Bundler dependency management system version 1.x, presenting a significant security risk that could enable remote attackers to execute arbitrary Ruby code within affected applications. This flaw specifically exploits gem name collisions that occur when multiple sources are configured in the bundler environment, creating opportunities for malicious code injection through carefully crafted gem names that conflict with legitimate dependencies.
The technical implementation of this vulnerability stems from Bundler's handling of gem resolution across multiple sources without proper validation of gem names and their associated metadata. When a secondary source contains a gem with the same name as one in the primary source, the system may inadvertently resolve to the malicious version from the secondary source, particularly if the secondary source is untrusted or compromised. This behavior creates a race condition in dependency resolution where the order of source resolution becomes critical to security. The vulnerability operates under CWE-400, specifically addressing improper input validation in dependency resolution mechanisms, while also aligning with ATT&CK technique T1059.007 for Ruby-based command execution through malicious gem installations.
The operational impact of this vulnerability extends beyond simple code injection, as it can lead to complete system compromise when attackers leverage the gem name collision to deliver malicious payloads through legitimate-looking dependencies. Applications using Bundler 1.x that have configured multiple gem sources become vulnerable to attacks where attackers can poison secondary sources with malicious gems that match names of legitimate dependencies. This creates a persistent threat vector that can remain undetected for extended periods, as the malicious code injection occurs during the normal dependency resolution process, making it appear as legitimate application behavior. The vulnerability is particularly dangerous in environments where developers rely on multiple gem sources without proper source verification mechanisms.
Mitigation strategies for CVE-2016-7954 require immediate attention and systematic implementation across affected systems. Organizations should upgrade to Bundler version 2.x or later, which addresses this vulnerability through improved gem resolution logic and enhanced source validation. When upgrading is not immediately possible, administrators should implement strict source verification practices including pinning gem sources to specific URLs, implementing source authentication mechanisms, and regularly auditing gem dependencies for suspicious patterns. Additional protective measures include configuring Bundler to use only trusted sources, implementing dependency lock files to prevent unauthorized gem resolution, and establishing monitoring systems to detect anomalous gem resolution behavior. The vulnerability's overlap with CVE-2013-0334 indicates this represents a persistent weakness in Bundler's dependency resolution architecture that requires fundamental architectural changes to address properly.