CVE-2014-3916 in Ruby
Summary
by MITRE
The str_buf_cat function in string.c in Ruby 1.9.3, 2.0.0, and 2.1 allows context-dependent attackers to cause a denial of service (segmentation fault and crash) via a long string.
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Analysis
by VulDB Data Team • 10/19/2018
The vulnerability identified as CVE-2014-3916 represents a critical memory management flaw within the Ruby programming language implementation that affects versions 1.9.3, 2.0.0, and 2.1. This issue resides in the str_buf_cat function located within the string.c file, which forms a fundamental component of Ruby's string handling infrastructure. The vulnerability manifests when the function processes exceptionally long strings, creating a scenario where attackers can manipulate the program's memory management behavior to trigger unexpected termination conditions.
The technical nature of this vulnerability stems from inadequate bounds checking within the str_buf_cat function, which is responsible for concatenating string buffers in Ruby's internal string operations. When processing strings that exceed predetermined memory allocation limits, the function fails to properly validate input parameters and memory boundaries, leading to memory corruption conditions. This flaw operates within the context of Ruby's memory management system and specifically impacts how the interpreter handles string concatenation operations that exceed normal operational parameters.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system instability and application crashes. Context-dependent attackers can exploit this weakness by crafting specially formatted long strings that, when processed by Ruby applications, will trigger segmentation faults and subsequent program termination. The vulnerability is particularly concerning because it affects multiple major Ruby versions simultaneously, indicating a systemic issue within the language's core string handling mechanisms. Applications running on affected Ruby versions become susceptible to denial of service attacks that can be executed without requiring elevated privileges or specialized access conditions.
The exploitability of CVE-2014-3916 aligns with attack patterns documented in the MITRE ATT&CK framework under the execution and privilege escalation domains, as attackers can leverage this vulnerability to disrupt service availability and potentially gain unauthorized control over affected systems. From a CWE perspective, this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios, both of which represent fundamental memory corruption vulnerabilities. The vulnerability's classification as a denial of service condition places it within the broader category of availability attacks that compromise system integrity and user experience.
Organizations affected by this vulnerability should prioritize immediate patching of all Ruby installations running versions 1.9.3, 2.0.0, and 2.1 to prevent exploitation. The recommended mitigation strategy involves upgrading to patched versions of Ruby that contain corrected memory management routines within the string.c file. Additionally, implementing input validation measures at application level can provide additional defense-in-depth protection against malformed string inputs that might trigger the vulnerability. System administrators should also monitor application logs for unusual string processing patterns that could indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper memory management in interpreted languages and highlights the need for comprehensive security testing of core language components to prevent similar issues from emerging in future releases.