CVE-2015-7581 in Ruby on Rails
Summary
by MITRE
actionpack/lib/action_dispatch/routing/route_set.rb in Action Pack in Ruby on Rails 4.x before 4.2.5.1 and 5.x before 5.0.0.beta1.1 allows remote attackers to cause a denial of service (superfluous caching and memory consumption) by leveraging an application's use of a wildcard controller route.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability described in CVE-2015-7581 affects Ruby on Rails applications that utilize wildcard controller routes within their routing configuration. This issue resides in the actionpack component of Ruby on Rails, specifically in the route_set.rb file which handles route resolution and caching mechanisms. The flaw manifests when applications employ wildcard routes that capture controller names, creating a scenario where malicious input can trigger excessive memory consumption through improper caching behavior.
The technical implementation of this vulnerability stems from how Rails processes wildcard routes in the routing system. When a route pattern includes a wildcard parameter that captures controller names, the framework's caching mechanism fails to properly handle the caching of these dynamic route patterns. This results in superfluous cache entries being created for each unique input pattern, leading to unbounded memory growth over time. The vulnerability specifically impacts versions before 4.2.5.1 and 5.0.0.beta1.1, indicating that these were the first releases to address the flawed caching logic in the route resolution process.
From an operational perspective, this vulnerability enables remote attackers to perform denial of service attacks against Ruby on Rails applications by crafting malicious requests that exploit the wildcard route handling. The attack requires only that the target application uses wildcard controller routes, which are commonly implemented for flexible routing patterns. Each malicious request consumes additional memory resources through the creation of excessive cache entries, eventually leading to application performance degradation or complete service unavailability. This makes the vulnerability particularly dangerous in high-traffic environments where memory resources are already constrained.
The impact of this vulnerability aligns with CWE-400, which categorizes it as an uncontrolled resource consumption issue. The flaw represents a classic resource exhaustion attack vector where the attacker can consume system resources without proper bounds. According to ATT&CK framework, this vulnerability maps to T1499.004, which covers "Endpoint Denial of Service" through resource consumption attacks. Organizations running affected Ruby on Rails applications are particularly vulnerable as the attack can be executed remotely without requiring authentication or specialized privileges beyond normal application access.
Mitigation strategies for CVE-2015-7581 primarily involve upgrading to the patched versions of Ruby on Rails 4.2.5.1 or 5.0.0.beta1.1. Additionally, application developers should review their routing configurations to identify and eliminate wildcard controller routes that could be exploited. Implementing rate limiting and request validation mechanisms can provide additional protection layers. Security monitoring should include tracking memory usage patterns and cache growth to detect potential exploitation attempts. Organizations should also consider implementing automated patch management processes to ensure timely deployment of security updates and maintain awareness of similar vulnerabilities in their application dependencies.