CVE-2013-0285 in nori gem
Summary
by MITRE
The nori gem 2.0.x before 2.0.2, 1.1.x before 1.1.4, and 1.0.x before 1.0.3 for Ruby does not properly restrict casts of string values, which allows remote attackers to conduct object-injection attacks and execute arbitrary code, or cause a denial of service (memory and CPU consumption) involving nested XML entity references, by leveraging Action Pack support for (1) YAML type conversion or (2) Symbol type conversion, a similar vulnerability to CVE-2013-0156.
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Analysis
by VulDB Data Team • 03/17/2019
The nori gem vulnerability CVE-2013-0285 represents a critical security flaw in Ruby applications that process XML data through Action Pack frameworks. This vulnerability affects multiple versions of the nori gem including 2.0.x before 2.0.2, 1.1.x before 1.1.4, and 1.0.x before 1.0.3, creating a widespread risk across numerous Ruby applications that rely on XML parsing capabilities. The flaw stems from improper handling of type conversions during XML processing, specifically when dealing with YAML and Symbol type conversions that are commonly used in Ruby web applications.
The technical implementation of this vulnerability involves the gem's failure to properly validate and restrict string value casts during XML parsing operations. When Action Pack processes XML data containing nested entity references, the nori gem attempts to convert these values into Ruby objects through automatic type detection mechanisms. Attackers can exploit this by crafting malicious XML payloads that contain specially constructed nested entities, which when processed by the vulnerable gem trigger unintended object injection behaviors. This occurs because the gem does not adequately sanitize input values before performing type conversions, allowing attackers to inject arbitrary Ruby objects into the application's memory space.
The operational impact of CVE-2013-0285 extends beyond simple code execution to encompass both remote code execution capabilities and denial of service conditions. Attackers can leverage this vulnerability to execute arbitrary code on affected systems, potentially gaining full control over the application server. Additionally, the vulnerability can be used to perform resource exhaustion attacks by crafting XML entities that consume excessive memory and CPU cycles during processing. The similarity to CVE-2013-0156 indicates this represents a broader class of vulnerabilities affecting Ruby applications that improperly handle YAML deserialization, making it particularly dangerous in environments where XML processing is common. The vulnerability affects the core object conversion mechanisms within Ruby applications, potentially compromising entire application stacks when exploited.
Security professionals should implement immediate mitigations including updating to patched versions of the nori gem, specifically version 2.0.2, 1.1.4, or 1.0.3 respectively. Organizations must also review their XML processing pipelines to ensure proper input validation and sanitization before any XML data is parsed through Action Pack components. Network segmentation and input filtering should be implemented at multiple layers to prevent exploitation attempts, while monitoring systems should be configured to detect unusual patterns in XML processing activities. The vulnerability aligns with CWE-707 and ATT&CK techniques related to injection attacks and privilege escalation, making it a significant concern for organizations following security frameworks that emphasize proper input validation and secure coding practices. Regular security assessments and dependency updates should be part of ongoing security operations to prevent similar vulnerabilities from being exploited in the future.