CVE-2008-3905 in Ruby
Summary
by MITRE
resolv.rb in Ruby 1.8.5 and earlier, 1.8.6 before 1.8.6-p287, 1.8.7 before 1.8.7-p72, and 1.9 r18423 and earlier uses sequential transaction IDs and constant source ports for DNS requests, which makes it easier for remote attackers to spoof DNS responses, a different vulnerability than CVE-2008-1447.
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Analysis
by VulDB Data Team • 08/18/2019
The vulnerability described in CVE-2008-3905 affects Ruby's DNS resolution functionality through the resolv.rb library, impacting versions up to and including Ruby 1.8.7-p72 and Ruby 1.9 r18423. This issue stems from the predictable nature of DNS transaction identifiers and source port selection during DNS queries. The flaw creates a significant security risk by making DNS response spoofing attacks more feasible for remote attackers who can exploit the predictable patterns in the DNS communication process. The vulnerability is particularly concerning because it operates at the fundamental level of network communication protocols, affecting how Ruby applications interact with DNS servers.
The technical implementation of this vulnerability involves the use of sequential transaction IDs and constant source ports when making DNS requests. In standard DNS operations, transaction IDs should be randomly generated to prevent attackers from predicting the sequence of DNS queries and responses. Similarly, source ports should be randomized to avoid predictable connection patterns. However, Ruby's resolv.rb library fails to implement these security measures properly, creating a predictable communication pattern that attackers can exploit to inject malicious DNS responses. This behavior directly violates the principles of secure network communication and makes the system vulnerable to cache poisoning attacks. The vulnerability aligns with CWE-330, which addresses the use of insufficiently random values, and represents a specific implementation weakness in the DNS resolution process.
The operational impact of this vulnerability extends beyond simple DNS spoofing capabilities, as it affects any Ruby application that relies on DNS resolution for network operations. Attackers can exploit this weakness to redirect traffic to malicious servers, intercept communications, or perform man-in-the-middle attacks against applications using affected Ruby versions. The vulnerability is particularly dangerous in environments where Ruby applications handle sensitive data or perform authentication through DNS-based services. Organizations running web applications, network services, or any Ruby-based systems that make DNS queries are at risk of having their DNS resolution compromised, potentially leading to complete system compromise. This vulnerability is categorized under the MITRE ATT&CK framework as a technique for DNS tunneling and cache poisoning, specifically targeting the network infrastructure layer.
Mitigation strategies for this vulnerability require immediate patching of affected Ruby installations to versions that properly implement randomized transaction IDs and source ports. System administrators should prioritize updating Ruby environments to versions that address this specific DNS resolution weakness, typically Ruby 1.8.6-p287, 1.8.7-p72, or later releases. Additionally, network-level protections such as DNS security extensions (DNSSEC) can provide defense-in-depth against DNS spoofing attempts, though they do not directly address the root cause of the vulnerability in Ruby's implementation. Organizations should also consider implementing network monitoring to detect unusual DNS traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper randomization in network protocols and serves as a reminder of the need for security-conscious implementation practices in language libraries that handle network communications, particularly in the context of DNS resolution and response validation mechanisms.