CVE-2017-0904 in private_address_check Ruby Gem
Summary
by MITRE
The private_address_check ruby gem before 0.4.0 is vulnerable to a bypass due to use of Ruby's Resolv.getaddresses method, which is OS-dependent and should not be relied upon for security measures, such as when used to blacklist private network addresses to prevent server-side request forgery.
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Analysis
by VulDB Data Team • 01/10/2023
The CVE-2017-0904 vulnerability affects the private_address_check ruby gem version 0.4.0 and earlier, representing a critical security flaw in network address validation mechanisms. This vulnerability stems from the gem's reliance on Ruby's Resolv.getaddresses method for determining whether IP addresses fall within private network ranges, creating a fundamental weakness in the security architecture. The issue manifests when the gem attempts to blacklist private network addresses to prevent server-side request forgery attacks, a common security pattern in web applications that rely on address validation to protect against internal network access.
The technical flaw resides in the OS-dependent behavior of Ruby's Resolv.getaddresses method, which can produce inconsistent results across different operating systems and network configurations. This method's reliance on underlying system DNS resolution mechanisms means that the gem cannot guarantee consistent address validation, particularly when dealing with private network ranges. The vulnerability allows attackers to bypass security checks by exploiting the inconsistent behavior of the DNS resolution process, potentially enabling them to access internal network resources that should be restricted. This bypass capability directly undermines the intended security controls and creates a pathway for server-side request forgery attacks.
The operational impact of this vulnerability extends beyond simple network access bypasses, as it fundamentally compromises the integrity of address validation systems within Ruby applications. Applications that depend on the private_address_check gem for security purposes may unknowingly allow unauthorized access to internal resources, potentially exposing sensitive data or systems to malicious actors. The vulnerability affects the broader Ruby ecosystem and demonstrates how seemingly innocuous network validation methods can create security holes when deployed in security-critical contexts. Organizations using affected versions of the gem face significant risk of internal network compromise and potential data breaches.
Mitigation strategies for CVE-2017-0904 require immediate action to upgrade to version 0.4.0 or later of the private_address_check gem, which addresses the underlying implementation issues. Security teams should conduct comprehensive audits of all applications using this gem to identify potential attack vectors and ensure proper network segmentation. The vulnerability aligns with CWE-200, which addresses improper error handling and information exposure, and relates to ATT&CK technique T1190 for exploitation of remote services. Organizations should also consider implementing additional network-level controls and monitoring to detect potential exploitation attempts, while ensuring that all network validation logic follows established security principles and does not rely on OS-dependent methods for critical security functions.