CVE-2017-16516 in yajl-ruby gem
Summary
by MITRE
In the yajl-ruby gem 1.3.0 for Ruby, when a crafted JSON file is supplied to Yajl::Parser.new.parse, the whole ruby process crashes with a SIGABRT in the yajl_string_decode function in yajl_encode.c. This results in the whole ruby process terminating and potentially a denial of service.
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Analysis
by VulDB Data Team • 01/06/2023
The vulnerability identified as CVE-2017-16516 affects the yajl-ruby gem version 1.3.0, a popular ruby library for parsing json data. This issue represents a critical denial of service vulnerability that can be exploited through maliciously crafted json input. The vulnerability manifests when the Yajl::Parser.new.parse method processes specially constructed json files, causing the ruby process to terminate abruptly with a SIGABRT signal. This behavior occurs within the yajl_string_decode function located in the yajl_encode.c source file, indicating a fundamental flaw in the json parsing implementation that leads to process termination rather than graceful error handling.
The technical exploitation of this vulnerability involves crafting specific json input that triggers an abnormal termination within the underlying yajl library. When the ruby process attempts to parse such malformed input, the yajl_string_decode function encounters conditions that cause it to issue a SIGABRT signal, effectively killing the entire ruby process. This represents a classic buffer overflow or memory corruption vulnerability where the parsing logic fails to properly validate input boundaries, leading to an abrupt process exit. The vulnerability demonstrates poor error handling practices and inadequate input sanitization within the json parsing pipeline, as legitimate error conditions should result in appropriate exception handling rather than process termination.
The operational impact of CVE-2017-16516 extends beyond simple service disruption, as it can be leveraged by attackers to perform denial of service attacks against ruby applications that utilize the yajl-ruby gem. Systems relying on json parsing for data exchange, api communications, or configuration management become vulnerable to this attack vector, potentially leading to complete application unavailability. This vulnerability particularly affects web applications, api servers, and any ruby-based systems that accept external json input from untrusted sources, making it a significant concern for production environments where reliability and uptime are critical. The vulnerability can be exploited remotely through any interface that processes json data, including web forms, api endpoints, and file upload mechanisms.
Mitigation strategies for this vulnerability should focus on immediate remediation through version updates, as the issue has been addressed in subsequent releases of the yajl-ruby gem. Organizations should implement comprehensive input validation and sanitization measures, ensuring that all json data processing includes proper error handling and boundary checking. The implementation of defensive programming practices, including proper exception handling and resource management, can help prevent similar vulnerabilities from manifesting in other components of the application stack. Additionally, deployment of web application firewalls and input filtering mechanisms can provide additional layers of protection against malformed json input that could trigger similar crashes. This vulnerability aligns with CWE-121, heap-based buffer overflow, and represents a typical ATT&CK technique for privilege escalation through service disruption, making it essential for security teams to prioritize patch management and input validation improvements across their ruby application environments.